Chapter 25: Collecting pollen for genetic resources conservation

Gayle M. Volk
National Center for Genetic Resources Preservation USDA-ARS, Fort Collins, USA
E-mail: Gayle.Volk(at)ars.usda.gov

This chapter is a synthesis of new knowledge, procedures, best practices and references for collecting plant diversity since the publication of the 1995 volume Collecting Plant Genetic Diversity: Technical Guidelines, edited by Luigi Guarino, V. Ramanatha Rao and Robert Reid, and published by CAB International on behalf of the International Plant Genetic Resources Institute (IPGRI) (now Bioversity International), the Food and Agriculture Organization of the United Nations (FAO), the World Conservation Union (IUCN) and the United Nations Environment Programme (UNEP). The original text for Chapter 25: Collecting Pollen for Genetic Resources Conservation, authored by F. A. Hoekstra, has been made available online courtesy of CABI. The 2011 update of the Technical Guidelines, edited by L. Guarino, V. Ramanatha Rao and E. Goldberg, has been made available courtesy of Bioversity International.

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References for this chapter

	Germinating pecan pollen. (Photo: J. Waddell/USDA-ARS - National Center for Genetic Resources Preservation).

Abstract

Pollen is a useful source of diverse alleles within a genepool and so may be an effective propagule for genebanks. The ease of pollen storage and shipment and the potential for its immediate use provide researchers with increased options when designing their breeding programs. Methods for pollen collection, desiccation, viability testing and longevity assessment have been developed for many species of interest, and have revealed the critical importance for increased longevity by using high quality pollen desiccating it sufficiently in a rapid manner and subsequently storing it at very low temperatures. Reliable viability assessments are dependent upon adequate rehydration and the use of reliable stains, in vitro germination assays or in vivo pollination experiments. Pollen preservation in genebanks will likely be implemented as standard procedures for handling and assessing it are developed.

Current Status

Advantages to the use of pollen

• Genebanked pollen can be made available to breeders upon request. For tree species, this obviates the need for growing the male parents in the breeding orchards. It allows for wide hybridization across seasonal and geographical limitations, and reduces the coordination required to synchronize flowering and pollen availability for use in crosses (Bajaj 1987). With adequate pollen available, one can also load additional pollen onto stigmas to increase pollination and yield.

• Pollen is available for research programs. As single cells, pollen provides a simple model system for research on conservation. Storage of pollen within genebanks also ensures its availability year-round for basic biology and allergy research programs (Shivanna 2003).

• Pollen captures diversity within small sample sizes, and documentation is available for long-term survival of pollen from many diverse species (table 25.1). Pollen also serves as a source of genetic diversity in collections where it is hard to maintain diversity with seeds (species of low fecundity, large seeds, or seeds that require an investment of labour to store).

• Pollen can also be shipped internationally, often without threat of disease transfer (Hoekstra 1995).

Table 25.1. A Selection of Species for Which Pollen Can Be Successfully Stored at –80°C or Liquid Nitrogen (LN) Temperatures

 Disadvantages to the use of pollen

• Limited pollen production in some species. The primary limitation in the routine implementation of pollen storage within genebanks is the difficulty in obtaining adequate quantities of pollen for many species.

• Labour-intensive collection or processing. For some species, pollen is readily available, but resources to accumulate and process enough pollen for routine storage and distribution are inadequate.

• No standardized processing or viability-testing protocols. Processing and viability-testing methods have not been documented and standardized in a manner similar to that of seed testing.

• Regeneration of aged pollen. Seed regeneration can often be performed directly using the seed samples in storage. For pollen, associated mother plants are necessary to replenish pollen supplies when quantities are depleted or have deteriorated (Schoenike and Bey 1981).

Pollen collection

Collected pollen serves to maintain and preserve the alleles of an individual or population. Sampling strategies have often recommended collecting a set number of individuals per population to ensure that the common alleles are captured. The exact number of individuals that most effectively captures the genetic variation is dependent upon the genetic diversity and life-history traits of the species (Lockwood et al. 2006). Namkoong (1981) suggests that collecting pollen from a single tree easily captures the alleles for that genotype; however, it is recommended that a minimum of 68 trees be sampled to represent a wild population. Pollen can also be collected from individual trees within a genebank both to conserve alleles specific to each individual and to provide male gametes for breeding purposes. Although only small quantities of pollen are required to capture the genes of an individual, because of the challenges of pollen collection and processing, it might be more efficient to collect larger quantities to ensure its long-term availability to the user community.

Pollen should be harvested soon after anthesis, usually in the morning hours (Ganeshan et al. 2008; Towill 2004). Shelf life is short for pollen collected from immature, aged, or weather-damaged anthers (Towill 1985). It is usually more practical to collect anthers in the field and then separate the pollen grains from the anthers in a laboratory environment soon after collection. All pollen must be processed immediately (within hours) to ensure maximum potential longevity.

	Storage of pollen for long-term preservation (photo: John Waddell, USDA-ARS-National Center for Genetic Resources Preservation).

Pollen desiccation

Successful pollen genebanking is dependent upon achieving long-term survival of stored pollen. Water content, cooling rate and storage temperature all affect the longevity of stored pollen (Buitink et al. 1996, 2000). Field conditions and relative humidity at the time of harvest affect the pollen moisture content, and germinability is impaired when pollen is kept for any length of time in wet or high-humidity conditions (Hoekstra 1986). Pollen ages quickly when held at 24°C and 75% relative humidity (RH) (Van Bilsen et al. 1994).

For desiccation-tolerant pollen, it is critical that the pollen be dried to a target moisture content soon after harvest. Depending on species, successful long-term storage requires that the moisture content be reduced to or below levels at which there is no free water (Priestley 1986). For many species, pollen can be dried to water contents of 0.05 g H₂O g^-1 dry weight (DW) without a loss in viability (Hoekstra 1986). This can be achieved by drying overnight in a low-humidity room environment or over salt chambers that are maintained at RH of about 30%. Equilibration over salt slurries, such as magnesium chloride or calcium nitrate, prevents damage that could result from over drying within ovens. It is a straightforward method to control moisture content in diverse laboratory environments (Connor and Towill 1993; Towill 1985).

Anthers or pollen grains can also be dried over silica gel at room temperature (Ganeshan 1985; Parfitt and Ganeshan 1989; Parton et al. 1998; Sacks and St. Clair 1996; Van der Walt and Littlejohn 1996). Martinez-Gómez et al. (2002) successfully desiccated almond pollen with silica gel for 48 hours at 22°C for long-term storage. Sato et al. (1998) dehydrated anthers at 20°C for 16–24 hours at RH of 15% or 32% prior to storage. Although some researchers have demonstrated successful desiccation through the use of freeze-driers for pollen desiccation, concerns have arisen with regard to maintaining viability in pollen that has been frozen prior to dehydration (Ganeshan and Alexander 1986, 1987; Perveen and Khan 2008). Towill (1985) argued that vacuum drying was as effective as freeze-drying for maintaining pollen viability. Although air at low RH will increase the drying rate, pollen must be removed before it dries to a lethal moisture level (1% to 2 % for peach and pine, 3.5% for coconut pollen) (Towill 1985). Pollen can be successfully dried in 35°C ovens, but care must be taken not to over dry under these conditions (Yates et al. 1991).

Rapid air-drying can also be achieved by using specialized pollen-dryers that blow air at 20% to 40% RH and 20°C, to quickly reduce moisture content in the pollen of Poaceae species, including Avena, Pennisetum, Saccharum, Secale, Triticum, Tricosecale and Zea (Barnabás and Kovacs 1996). Maize pollen is easily stored when quickly dried to 0.19 g H₂O g^-1 DW (Buitink et al. 1996).The longevity of the pollen from these desiccation-sensitive species, and its tolerance to freezing temperatures, has been extended as a result of using rapid dehydration methods. The principle of rapid drying (flash drying) has successfully been documented in recalcitrant seeds, where it was shown that one could dry to a much lower water content if one did it rapidly (Pammenter et al. 1991).

Storage temperature

It is possible to store pollen of many species at temperatures between 4°C and –20°C for the short-term. Dry pollen that is kept at between 4°C and –20°C remains viable for a few days to a year, which may be adequate for use in breeding programs (Hanna and Towill 1995).

Long-term viability can be maintained by storing pollen at –80°C or LN temperatures (–196°C) (Hanna and Towill 1995). Once desiccated, pollen can be dispensed into cryovials for long-term storage in LN or LN vapour. Precise labelling of vials and storage locations is recommended to aid in future retrieval of samples. Vials can then be placed in boxes or cryocanes and directly immersed in the liquid or vapour phase of liquid nitrogen (Barnabás and Kovács 1996; Ganeshan et al. 2008; Hanna and Towill 1995; Connor and Towill 1993).

Pollen rehydration

Dried pollen is susceptible to injury from rapid water update during rehydration (also known as imbibitional injury) (Hoekstra and Van der Wal 1988), which can severely reduce germination and lead to low viability counts if vital staining (stains to identify living cells) is used to assess it. Low temperatures can exacerbate imbibitional damage, which is believed to arise from mechanical damage to the plasma lemma as polar lipids undergo phase changes as a result of fluctuations in temperature, water content and sugars (Hoekstra et al. 1992; Hoekstra and Van der Wal 1988; Crowe et al. 1989). Slow rehydration ameliorates imbibitional damage to pollen grains and this is usually accomplished by placing the pollen in a humid environment prior to direct liquid exposure (Hoekstra and Van der Wal 1988; Luza and Polito 1987; Parton et al. 2002). Pollen rehydration can be as straightforward as placing open vials of pollen in 100% humidity environments for 1 to 4 hours at room temperature (Connor and Towill 1993; Hanna and Towill 1995).

Although suboptimal storage conditions may affect pollen vigour before a measurable change in pollen viability is observed, most studies make use of viability assessments (Shivanna et al. 1991). Pollen viability can be measured by vital staining pollen grains, by germinating pollen grains in vitro, or by demonstrating successful fertilization and seed development in plants.

Pollen viability

	Viability staining (thiazolyl blue tetrazolium) for pecan pollen grains (photo: John Waddell, USDA-ARS-National Center for Genetic Resources Preservation).

Staining

One commonly used vital stain is the fluoregenic ester, fluorescein diacetate (FDA). This test measures membrane integrity. Pollen grains fluoresce green when a cellular esterase cleaves the FDA (Heslop-Harrison and Heslop-Harrison 1970). Since this assay is dependent upon functional membranes, the osmoticum of the FDA staining solution is critical; stain is often dissolved in a 10% to 20% sucrose solution containing boric acid and calcium nitrate to minimize plasmolysis and membrane leakage.

Comparisons of viability determined through the use of FDA or tetrazolium and those obtained using in vitro germination or in vivo fertilization tests reveal consistently high correlations, provided pollen is adequately rehydrated prior to testing (Firmage and Dafni 2001; Khatun and Flowers 1995; Rodriguez-Riano and Dafni 2000; Shivanna and Heslop-Harrison 1981). FDA has occasionally been shown to give false negative results, where viable pollen appears dead (Heslop-Harrison et al. 1984).

Several tetrazolium-based stains are available for testing pollen viability (Norton 1966). The 3 (4,5-dimethyl thiazolyl 1-2) 2,5-diphenyl tetrazolium bromide (MTT) test was shown to give the most dependable results in a comparison trial using plum pollen (Norton 1966). In general, tetrazolium tests measure the ability to reduce colourless tetrazolium to coloured formazan, thus identifying pollen that has a capacity for oxidative metabolism (Hauser and Morrison 1964).

Many other vital stains have been developed and proposed over the past 50 years. Stains such as Alexander‟s, acetocarmine, aniline blue and X-gal have been shown to be successful identifiers of viability for relatively few species or under specialized conditions (Rodriguez-Riano and Dafni 2000). Viability results obtained with these stains may not correlate well with in vitro germination assays (Towill 1985).

In vitro germination

Pollen can be germinated in vitro by placing pollen grains onto a medium and measuring the elongation of the pollen tube after a few hours of imbibition. Pollen tubes that elongate to a length that is at least the diameter of the pollen grain are considered viable (Dafni and Firmage 2000). Automated counting procedures using morphometry software result in pollen counts that are within 5% of visual observations and allow the determination of pollen tube length in addition to the data obtained by eye on tube presence or absence (Pline et al. 2002). These automated systems may expedite time-consuming assays of in vitro pollen germination. As for viability testing, it is important to implement repeatable and standardized methods and to use dead pollen samples as controls.

The optimal temperature for in vitro germination assays can be species dependent. The pollen from many species germinates well at 25°C; however, differences exist. For example, cotton pollen has an optimum germination temperature of 28°C to 31°C (Burke et al. 2004). Hence, for the purpose of pollen conservation, such information should be known for the target species.

In vitro germination methods utilize pollen immersed in aerated solutions, “hanging” drops, or dispersed on solidified medium. The medium is often that described by Brewbacker and Kwack (1963) or a slight modification thereof. Boric acid, calcium nitrate and sucrose concentrations in the medium might have to be optimized according to species (Bolat and Pirlak 1999; Heslop-Harrison 1992). The hanging-drop method involves the placement of a slide or coverslip with liquid medium and pollen inverted over a 100% humidity chamber (Rajasekharan and Ganeshan 1994). For observation, the slide is returned to an upright position and observed under a microscope.

Pollination

Testing viability by observing pollen tube elongation within the stigma or fertilization and subsequent seed production is the most time-intensive way to determine pollen viability; however, these kinds of tests are also the most relevant to demonstrate the adequacy of the pollen for use. Rehydrated pollen can be placed on the stigmas of live plants, and tube length is measured after a pre-determined time interval (Dafni and Firmage 2000). Ideally, successful fruit set and seed production occurs after pollination with conserved pollen. Marquard (1992) demonstrated that high levels of viability are not required. Fruit set occurred when stigmas were treated with only 5% viable pollen. When pollen appears viable based on germination tests, it is often also viable in fertilization assays.

Pollen longevity

The longevity of pollen is dependent upon many factors specific to cultivars or species as well as handling procedures, as discussed here (Ganeshan and Alexander 1991; Hanna and Towill 1995). The presence of sucrose and polysaccharides in the pollen has been correlated with protection of membranes from desiccation or temperature stress and may confer greater longevity (Dafni and Firmage 2000; Hoekstra et al. 1989). High-quality pollen dehydrated to an optimal moisture content and stored at LN temperatures has been documented to store for well over 10 years (Panella et al. 2009; Sparks and Yates 2002). The low temperature reduces the molecular mobility in the cytoplasm, which may be a controlling factor in pollen longevity (Buitink et al. 2000). The aging of dried pollen is likely caused by oxidative reactions, and pollens with higher levels of unsaturated fatty acids usually have a shorter shelf life (Hoekstra 2005). Correspondingly, pollen longevity may be further improved by storing desiccated pollen in an oxygen-free atmosphere (Hoekstra 1992).

Most reports describing pollen survival after LN exposure state viability levels after determined lengths of time, often without initial germination data. These end-point levels serve to demonstrate that the tested length of storage is possible, but they do not describe the longevity of the pollen per se. Table 25.1 demonstrates the diverse range of species for which pollen can be placed at LN temperatures. According to current information, it is clear that both desiccation-tolerant and non-desiccation-tolerant pollen types can be stored for over 10 years under controlled conditions (Barnabás1994; Barnabás and Kovács 1996; Shivanna 2003). Thus, despite additional challenges that may be present in storing desiccation-sensitive pollen, it is possible. Additional research is needed to determine how long both types of pollen will remain viable under these conditions. 

Future challenges/needs/gaps

Technologies for successful pollen conservation have been developed and are available. A set of standardized methods to process pollen types with different physiologies is needed to make pollen storage a routine effort in genebanks. For many species in need of pollen conservation, we need to know more about the phenology of pollen production so that we can properly time pollen harvests. Standards should be developed for pollen collection, processing and storage of desiccation-tolerant and non-desiccation-tolerant pollen types. Determination of pollen genebanking standards is an initial step towards implementing pollen genebanking methods.

The literature currently lists the age and viability of pollen from many species stored at LN temperatures (table 25.1) (Barnabás and Kovács 1996; Ganeshan and Rajashekaran 2000; Hanna and Towill 1995; Towill 1985). However, the viability over time, or longevity, of pollen stored under LN genebanking conditions has not been thoroughly evaluated. In addition, detailed biophysical studies should be pursued to determine the optimal water content, desiccation rates and longevity relationships for various pollen types. Longevity must be known in order to ascertain the cost and benefits of genebanking pollen.

Conclusions

There are abundant reports in the literature of many successes for testing pollen viability and temperature exposure. Many of the reported data and methods are difficult to replicate when basic parameters such as initial water content, equilibrated (desiccated) water content and rehydration methods are not described (Dafni and Firmage 2000). It is clear that the physiological state of the pollen at the time of collection and the handling of that pollen within the first few days after collection will determine its potential for long-term survival under optimum conditions. Detailed reporting of handling upon harvest is essential if standardized methods are to be developed. Confirmation that reported staining, in vitro germination and in vivo germination results are correlated increases confidence in and the repeatability of the reported data.

Despite the challenges, pollen is a valuable genetic resource for conservation. It provides breeders and researchers with an additional, complementary, propagule that may be immediately useful in their programs, although the feasibility of pollen collection and preservation varies among plant species.

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References and further reading

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Chapter 20: Collecting and handling seeds in the field

F. R. Hay
International Rice Research Institute, Metro Manila, Philippines
E-mail: f.hay(at)cgiar.org
R. J. Probert
Royal Botanic Gardens, Kew, Ardingly, Nr. Haywards Heath, West Sussex, UK
E-mail: r.probert(at)kew.org

This chapter is a synthesis of new knowledge, procedures, best practices and references for collecting plant diversity since the publication of the 1995 volume Collecting Plant Genetic Diversity: Technical Guidelines, edited by Luigi Guarino, V. Ramanatha Rao and Robert Reid, and published by CAB International on behalf of the International Plant Genetic Resources Institute (IPGRI) (now Bioversity International), the Food and Agriculture Organization of the United Nations (FAO), the World Conservation Union (IUCN) and the United Nations Environment Programme (UNEP). The original text for Chapter 20: Collecting and Handling Seeds in the Field, authored by R. D. Smith, has been made available online courtesy of CABI. The 2011 update of the Technical Guidelines, edited by L. Guarino, V. Ramanatha Rao and E. Goldberg, has been made available courtesy of Bioversity International.

Please send any comments on this chapter using the Comments feature at the bottom of this page. If you wish to contribute new content or references on the subject please do so here.

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Internet resources for this chapter

Abstract

	Appropriate handling of immature fruits can greatly improve seed quality for long-term storage. (Photo: RBG, Kew)

Seed banking remains a cornerstone in the conservation of plant genetic resources. To be successful, it relies on the collecting and banking of high-quality seeds. In 1995 there was relatively little guidance available to seed collectors (especially of wild plant species), who had to make decisions in the field about what to collect and how to handle collected material. Since then, research into various aspects of seed conservation has meant collectors should have a better idea of the storage behaviour and potential longevity of seeds of a target species and the likely maturity status of the collected seeds. Knowledge of the moisture status of the seeds, which can be quickly and easily determined in situ, and of the local climatic conditions, can help inform what to do with a collection immediately after harvest. A particular concern is that, while a relatively small proportion of species were known to have recalcitrant or intermediate seed storage behaviour, there may be many technically orthodox species whose seeds are so short-lived in conventional seed bank storage that alternative storage conditions or even methods of conservation will have to be sought.

Introduction

In the earlier version of this chapter, published in 1995, Roger Smith concluded that there was a scarcity of published data to aid collectors on the post-harvest handling of seeds. Shortly after that, Roger was responsible for leading the Millennium Seed Bank Project, the largest seed conservation effort for wild plant species ever undertaken. It is therefore no coincidence that a major thrust of research on seed storage behaviour, longevity, development and post-harvest handling began around that time.

In 1995, we knew that the moisture status of seeds at the time of collection and during the post-harvest period would have a major impact on subsequent seed longevity. Historical climate data could be used to predict the likely affects on seed longevity if seeds were exposed to average ambient conditions in the field. However, portable and reliable means of directly measuring seed moisture status and ambient conditions in the field were not widely available at that time; they are now and are already used by seed collectors around the globe.

Our knowledge of the relationship between seed maturity and the development of seed tolerance to desiccation and seed longevity is now also greatly improved, which has enabled the development of clear practical guidelines for post-harvest handling. We also have a much better understanding of the variation among species in inherent seed longevity and the factors that correlate with such differences. This good news, however, is tempered by the fact that we have now discovered wild plant species and crop relatives that are potentially extremely short lived using conventional techniques for seed conservation.

The global threat to plant diversity from land conversion, invasive species and climate change means that it is now more important than ever to collect and conserve plant genetic resources. Armed with the knowledge gained and tools developed since 1995, collectors can be more confident that collections will reach the seed bank in prime condition.

Current Status

Seed storage types

One of the first considerations when deciding how to collect and handle seeds of a particular species is storage behaviour. The Seed Information Database (SID) (http://data.kew.org/sid) began as an online version of the Compendium of Information on Seed Storage Behaviour (Hong et al. 1998), which categorized species as having recalcitrant, intermediate or orthodox seed storage behaviour based on published data and unpublished seed storage results from the Seed Bank of the Royal Botanic Gardens Kew. SID currently contains information on the seed storage behaviour of 19,676 species and can be searched at different levels of taxon (although not by common names). Most species for which information is available (93.9%) are described as having orthodox (or probably/likely orthodox) seed storage behaviour, although as observed previously, the species included in SID are probably biased towards temperate and/or useful plant species that might be more likely to have orthodox seed storage behaviour. Only 2.8% are described as having recalcitrant (or probably/likely recalcitrant) seed storage behaviour. The remaining species (0.8%) fall into the intermediate category of seed storage behaviour or have uncertain storage behaviour (based on the available data).

Where information is not found in SID or through other literature or web searching, it may be necessary to empirically determine seed storage behaviour, if seeds, time and facilities are available. Hong and Ellis (1996) presented an experimental scheme to determine seed storage behaviour whereby seeds are dried to increasingly lower moisture contents and tested for germination; samples of those that survive drying to 10% moisture content are further dried and stored at -18°C for three months and then tested again. This scheme requires a large number of seeds. Pritchard et al. (2004) described a simpler version where small samples of seeds are used for moisture content and germination testing before and after drying; drying to equilibrium with silica gel is monitored by following the change in seed weight. These types of experiments on desiccation tolerance assume that appropriate dormancy-breaking treatments and germination requirements are known. This might not be the case, and for example, as reported for Carica papaya, dormancy can be induced by drying (Wood et al. 2000). Similarly, if the low temperature response as well as the desiccation response is tested, as in the Hong and Ellis (1996) schematic, it should be noted that the low temperature might reduce germination for reasons other than loss of viability, per se. Crane et al. (2003) found that there was reduced germination of seeds of some Cuphea species due to the crystallization of particular fatty acids within the seeds. Higher germination was achieved if the seeds were given a heat pulse to melt these lipids before imbibition (a response that cannot be described as the induction and release of dormancy).

Recalcitrant seed storage behaviour is still expected to be more prevalent in the warm moist habitats of tropical and sub-tropical forests, compared with more arid areas, and these seeds tend to have particular characteristics: they are likely to be non-dormant, dispersed at a high seed moisture content (since they are metabolically active) and during the wettest months of the year, relatively large and likely to have relatively thin outer tissues (endocarp and testa) (Daws et al. 2005; Ellis et al. 2007; Berjak and Pammenter 2008). Daws et al. (2006) used these last two traits in a model that can be used to predict the likelihood of desiccation sensitivity. If there is a high probability of desiccation sensitivity, it would be unwise to make a large seed collection for conventional seed bank storage. The expected ‘hot spot’ of desiccation intolerance among aquatic species has not been entirely borne out. Hay et al. (2000) found that a considerable number (65) of aquatic plants native to the UK do produce seeds that could withstand desiccation; only nine species were described as having recalcitrant or intermediate storage behaviour based on levels of desiccation tolerance. Similarly, although less surprising, Tuckett et al. (2010) reported that seeds of aquatic species found in temporary pools of Western Australia have orthodox storage behaviour.

The extent of desiccation tolerated by seeds of species that are classified as having recalcitrant storage behaviour varies. This has led to the theory of a continuum of seed storage behaviour (for a review see Berjak and Pammenter 2008), from highly recalcitrant species, whose seeds tolerate little or no desiccation, through to extremely orthodox species, whose seeds are highly desiccation tolerant and long lived. Desiccation tolerance can even vary between different seed lots within a species and between individual seeds within a seed lot. Daws et al. (2004) showed how the degree of desiccation tolerance varied between seed lots of the recalcitrant species Aesculus hippocastanum, depending on provenance within its European range; differences were attributed to enhanced development of the seeds in warmer environments. Similarly for tropical species, the level of ‘maturity’ of the seed at shedding may determine the level of desiccation tolerated (Berjak et al. 1993; Lin and Chen 1995). Between species it has been observed that the slower the rate of water loss, the greater the desiccation sensitivity (Berjak and Pammenter 2008). Berjak and Pammenter (2008) also gave practical advice for the conservation of recalcitrant seeds: seeds should be kept at their harvest (or shedding) moisture content and at the lowest temperature that does not incur chilling damage. Seeds of species from temperate regions may tolerate lower temperatures (0-5°C) than species from tropical regions. Provided that fungal growth can be controlled, recalcitrant seeds may remain viable under such conditions for several months to a year or two, at best. For long-term ex situ conservation, cryopreservation techniques, often of excised embryonic axes, remains the only option for desiccation-sensitive species, including those that have been termed ‘intermediate’ but which might also be considered, on the continuum of desiccation tolerance, as ‘minimally recalcitrant’.

Desiccation-tolerant (orthodox) seeds

Orthodox seed development

The timing of seed collection is important since seed quality increases late in seed development: during the desiccation stage after the attainment of mass maturity (maximum seed dry weight). (Note that for orthodox seeds borne in fleshy fruits, there may be limited loss of water from the developing seed.) Understanding the physiology and patterns of gene expression of this stage of seed development continues to be a focus of seed research (for a review see Angelovici et al. 2010).

Seeds of many orthodox species acquire desiccation tolerance around the time of mass maturity, some time before the desiccation stage is completed and seeds, in the case of wild species, are dispersed. However, there are some seemingly orthodox species in which there is little or no desiccation phase before seed dispersal, and some individual seeds within a cohort that might be considered ready for collection (on the point of natural dispersal) might not be fully desiccation tolerant. This phenomenon has been observed in the spring-flowering herbaceous geophyte, Anemone nemorosa, where only 30% of the freshly harvested seeds survived drying for 21 days at 15% relative humidity (RH), 15°C (Ali et al. 2007). Desiccation tolerance increased during the first five days after harvest in seeds placed on agar at 20°C. This Anemone nemorosa data shows how seed maturity at harvest can vary between individual seeds. Hay et al. (2010) attempted to determine the sources of variability in seed maturity by following the development of a cohort of seeds of Trifolium ambiguum. They concluded that, for this species, seed-to-seed variability in the timing of the onset of germinability, desiccation tolerance and hardseededness, and in the gaining of seed longevity was inevitable. Seed collectors in the field, even when collecting from a crop species where there might be less variability in phenology and micro-environment between individual plants, are unlikely to be able to make a collection of seeds with completely uniform maturity. Attainment of maximum seed longevity in T. ambiguum was associated with a change in seed coat colour from orange to dark orange, although there were subsequent declines in potential longevity (Hay et al. 2010). A useful review of field markers of seed maturity, including changes in fruit and seed coat colour can be found in Hay and Smith (2003). Another potential marker of seed maturity is the amount of chlorophyll fluorescence emitted by the intact seeds since, for some species, the amount of chlorophyll in the seeds declines during seed development (Jalink et al. 1998). Whether such a technology could actually be of practical use on a seed-collecting expedition remains to be seen, but seed sorters that discriminate on the basis of either colour or chlorophyll fluorescence are available and could be used during the processing of seed accessions (Dell’Aquilla 2009).

Moisture content is also commonly used to assess seed maturity. However, empirical determination of seed moisture content is a destructive test and obviously requires laboratory facilities. Probert (2003) described how portable instruments that determine the equilibrium relative humidity (eRH)—the RH of the air around a sample when the system is in equilibrium—of a seed sample can be used to decide whether it is appropriate to make a collection or, if a collection is made, how the seeds should be processed. The use of digital hygrometers and alternatives for measuring seed moisture status has been described in more detail by Probert et al. (2003). These methods and practical guidelines for post-harvest handling of seeds (see below) are also covered by Millennium Seed Bank information sheets 04, 05, and 07 (www.kew.org/msbp/scitech/publications/info_sheets.htm). In dry climates, if the eRH of a sample of seeds is already close to ambient RH, seeds should be collected as soon as possible. If fruits/seeds do not easily detach from the maternal plant and the eRH of the seeds is still high (85%–100%), it is better to wait for further maturation before making a collection.

Handling seeds in the field

How seeds are handled immediately after harvest is critical to their subsequent longevity in storage. Particular care should be taken when a species’ seeds are expected to be extremely short-lived (see below). The timing of seed collection is also important; however, it might not always be possible to wait to collect seeds on the point of natural dispersal (as recommended for seeds of wild species) because of logistical constraints.

If fruits/seeds have a very high eRH at harvest (85%–100%) and if resources are available to create a controlled, non-desiccating environment, they should not be rapidly dried. Seed quality is likely to increase if such seeds are held under conditions (temperature, humidity) that are close to the conditions that they would experience if they remained on the maternal plant (Probert et al. 2007). As a general rule, suitable conditions to aim for would be ~75% RH and close to ambient temperature. During a collecting expedition, it might be more practical to simply hold intact fruits under shaded ambient conditions to allow continued ripening (table 20.1). Butler et al. (2009) found that if seeds are collected before the end of the desiccation phase of seed development and dried, developmental processes leading to increases in seed quality might be resumed if seeds are later placed at high humidity. This may be worth considering in situations where it has not been possible to hold seeds at high humidity immediately after harvest, although it needs validating for more species before it might be considered appropriate for routine use.

Table 20.1. Decision-Making Framework for Post-Harvest Handling of Orthodox Seeds from Non-Fleshy Fruits during Seed Collecting Missions, Based on an Understanding of Ambient Conditions and Seed Moisture Status

Note: For more details, see MSBP technical information sheets 04 and 05 (www.kew.org/msbp/scitech/publications/info_sheets.htm).

If the eRH of collected seeds is between 50% and 85%, the rate of aging is likely to be unacceptable. If the ambient conditions are also hot and humid, it will be necessary to dry the seeds as soon as possible using a desiccant and/or transfer the seeds to an air-conditioned or purpose-built dry room. In less humid climates, the seeds can be dried by placing them in a thin layer in a well-ventilated, shaded location. Seeds should not be allowed to take up moisture overnight when ambient air humidity increases. This can be prevented by sealing them in air-tight containers. For seeds that are already relatively dry at the time of collection, the advice is similar except that in dry climates, the seeds can be loosely packed in mesh or paper bags and kept in a ventilated location (table 20.1).

The eRH of fleshy fruits is likely to be high regardless of the maturity stage of the seeds inside, and there is little point in measuring the eRH of these fruits. Seeds from such fruits should be extracted as soon as physical signs (such as fruit colour) suggest that the fruits are ripe. Unripe fruits should be kept under ambient conditions and direct sunlight may not be unfavourable. Simulating natural conditions, extracted seeds should also be allowed to dry relatively slowly (i.e., aiming for the ~75% RH as above) before being transferred to the genebank dry room.

Variation in the longevity of orthodox seeds

Even if a species falls into the orthodox category of seed storage behaviour in that the seeds are desiccation tolerant, it does not mean that conventional seed bank storage is an appropriate method of ex situ conservation. There is increasing evidence that the seeds of some wild species are extremely short-lived in air-dry storage. For example, seeds of Anemone nemorosa are predicted to survive only a year or two at most under conventional seed bank conditions (Ali et al. 2007). This finding is consistent with those of Probert et al. (2009), who found that relatively short seed longevity in air-dry storage was correlated with the presence of endosperm and with cool, wet environments. Walters et al. (2005) similarly found taxonomic and climatic trends in relation to seed longevity among accessions (breeding lines, landraces, and wild populations) comprising 276 species, including many common crops, and Mondoni et al. (2011) have recently shown that seeds of Alpine plants were significantly shorter lived than related species and ecotypes from nearby lowland habitats. If collected seeds are expected to be very short-lived in air-dry storage, care is needed to ensure that viability is not lost before seeds arrive at the seed bank (see table 20.1). Li and Pritchard (2009) have suggested that it makes economic sense to use ultra-cold storage (in or above liquid nitrogen) for short-lived (indeed all) orthodox seeds, particularly for threatened and vulnerable wild species. At the extreme end of the orthodox scale, Probert et al. (2009) found that seeds from some Australian species were particularly long-lived, and Sallon et al. (2008) have reported germination of date seeds (Phoenix dactylifera L.) that were carbon dated to be about 2000 years old. Delays in the processing of such seeds would be less detrimental than for short-lived seeds, although best practice should nonetheless be followed.

The Ellis and Roberts (1980) improved viability equation remains a useful tool for predicting seed longevity in air-dry storage and also the potential losses that might be incurred if processing (drying and storage) is delayed, if the ‘viability constants’ have been determined for the species of interest. SID has a useful module that can be used to predict viability loss for species for which the viability constants of the equation have been determined. Currently, constants for 56 species are available in the database, including common cereal and legume crops as well as wild species. Constants for other species may be available in the literature, and the values can be entered within the seed-viability constants module of SID to make predictions. The module also allows the user to estimate equilibrium moisture content if the seed oil content for the species is known. Determining species viability constants for other species is relatively simple if the Dickie et al. (1990) universal values are used for the temperature constants, requiring experimental storage of seed samples to be carried out using a range of moisture contents at a single temperature (cf. a range of moisture contents and temperatures).

Future challenges/needs/gaps

The process of seed collecting always sounds as if it should be quite straightforward. However, in truth, if the seeds are to be of value as a genetic resource, we know that considerable care is needed in terms of deciding when and whether to collect and how to handle the seeds in the field. Collectors would still benefit from the development of fast, reliable tools for use in the field to diagnose seed storage behaviour, maturity stage, and perhaps, for orthodox seeds, potential longevity. Portable systems for efficient drying of seeds during a collecting trip or, if appropriate the converse, for holding them at high humidity, also need to be improved. More research is needed on potentially difficult and understudied groups: for example, temperate woodland geophytes, aquatic species and alpine species, whose seeds might be desiccation tolerant but very short-lived in conventional seed bank storage. Such studies might consider optimum time to collect, appropriate drying environments, treatments to overcome germination problems and dormancy, and alternative storage conditions.

Non-orthodox seeds still present considerable challenges, not least since a wide variety of species, including some important crops and/or their wild relatives, have seeds that are non-orthodox.

Conclusions

Key points restated and updated.

For all seeds

• Attempt to collect equal numbers of seeds from each plant sampled at the time of natural seed dispersal. Do not collect from the ground unless you can be sure seeds have only recently dispersed. Avoid damaged seeds (mechanical damage, pest attack).

• If seeds must be cleaned during the trip, do so by hand to minimize the chance of mechanical damage.

• Plan your activities so that no more than one month elapses between collecting and reception by the seed bank.

• If it is possible to avoid quarantine seed treatments without breaking quarantine regulations (for example through post-entry quarantine), do so.

• Personally ensure that seed arrives at the seed bank without undue delay. International air-freight companies offer a reliable service for sending seed batches around the world. Major companies provide online tracking services, and packages travel in pressurized, temperature-controlled aircraft cabins so there is little risk to seed quality during transit.

For desiccation-intolerant seeds

• Keep seeds aerated and moist in inflated polythene bags, changing the air at least weekly by deflation and re-inflation.

• Do not allow such seeds collected in the tropics to either cool below 20°C or heat up above ambient shade temperatures in the field or during transport.

For desiccation-tolerant seeds or their fruits

• Make direct measurements of seed moisture status and ambient conditions at the time of collection using a suitable hygrometer to assess the risk of significant loss in seed viability during transit. Use the results to inform post-harvest handling decisions (table 20.1).

• For fleshy-fruited species, if logistically possible consider field cleaning of fully ripe fruits followed by shade (slow) drying of extracted seeds for three days or more (larger seeds need longer) to reduce the seed moisture content towards equilibrium with ambient relative humidity before packing. If the fruits are not fully ripe, then keep the fruits intact and aerated, at ambient temperatures.

• For fruits that are dry dehiscent or indehiscent, it is usually preferable to keep the fruits intact and aerated, at ambient temperatures. However, to use space more efficiently, seeds could be extracted by hand and dried in the shade as above.

• Collections containing a significant proportion of immature seeds or fruits should be allowed to continue ripening under ambient conditions but protected from exposure to direct sunlight. Such collections should be regularly checked for physical indications of improved maturity.

• If the collection comprises morphologically distinct maturity stages, consideration should be given to splitting the collection and treating the immature and mature seeds differently.

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References and further reading

Ali N, Probert R, Hay F, Davies H, Stuppy W. 2007. Post-dispersal embryo growth and acquisition of desiccation tolerance in Anemone nemorosa L. seeds. Seed Science Research 17:155–163.

Angelovici R, Galili G, Fernie AR, Fait A. 2010. Seed desiccation: a bridge between maturation and germination. Trends in Plant Science 15:211–218.

Berjak P, Pammenter NW. 2008. From Avicennia to Zizania: seed recalcitrance in perspective. Annals of Botany 101:213–228.

Berjak P, Vertucci CW, Pammenter NW. 1993. Effects of developmental status and dehydration rate on characteristics of water and desiccation sensitivity in recalcitrant seeds of Camellia sinensis. Seed Science Research 3: 155–166.

Butler LH, Hay FR, Ellis RH, Smith RD. 2009. Post-abscission pre-dispersal seeds of Digitalis purpurea L. remain in a developmental state that is not terminated by desiccation ex planta. Annals of Botany 103:785–794.

Crane J, Miller AL, van Roekel JW, Walters C. 2003. Triacylglycerols determine the unusual storage physiology of Cuphea seed. Planta 217:699–708.

Daws MI, Garwood NC, Pritchard HW. 2005. Traits of recalcitrant seeds in a semi-deciduous tropical forest in Panamá: some ecological implications. Functional Ecology 19:874–885.

Daws MI, Garwood NC, Pritchard HW. 2006. Prediction of desiccation sensitivity in seeds of woody species: a probabilistic model based on two seed traits and 104 species. Annals of Botany 97:667–674.

Daws MI, Lydall E, Chmielarz P, Leprince O, Matthews S, Thanos CA, Pritchard JW. 2004. Developmental heat sum influences recalcitrant seed traits in Aesculus hippocastanum across Europe. New Phytologist 162:157–166.

Dell’Aquila A. 2009. Development of novel techniques in conditioning, testing and sorting seed physiological quality. Seed Science & Technology 37:608–624.

Dickie JB, Ellis RH, Kraak HL, Ryder K, Tompsett PB. 1990. Temperature and seed storage longevity. Annals of Botany 65:197–204.

Ellis RH, Roberts EH. 1980. Improved equations for the prediction of seed longevity. Annals of Botany 45:13–30.

Ellis RH, Mai-Hong T, Hong TD, Tan TT, Xuan-Chuong ND, Hung LQ, Ngoc-Tam B, Le-Tam VT. 2007. Comparative analysis by protocol and key of seed storage behaviour of sixty Vietnamese tree species. Seed Science & Technology 35:460–476.

Hay FR, Smith RD. 2003. Seed maturity: when to collect seeds from wild plants. In: Smith RD, Dickie JB, Linington SH, Pritchard HW, Probert RJ, editors. Seed Conservation: Turning Science into Practice. Royal Botanic Gardens, Kew, UK. pp. 97–133.

Hay F, Probert R, Marro J, Dawson M. 2000. Towards the ex situ conservation of aquatic angiosperms: a review of seed storage behaviour. In: Black M, Bradford KJ, Vázquez-Ramos J, editors. Seed Biology: Advances and Applications. CAB International, Wallingford, UK. pp. 161–177.

Hay FR, Smith RD, Ellis RH, Butler LH. 2010. Developmental changes in the germinability, desiccation tolerance, hardseededness, and longevity of individual seeds of Trifolium ambiguum. Annals of Botany 105:1035–1052.

Hong TD, Ellis RH. 1996. A Protocol to Determine Seed Storage Behaviour. IPGRI Technical Bulletin No. 1. IPGRI, Rome.

Hong TD, Linington SH, Ellis RH. 1998. Compendium of Information on Seed Storage Behaviour, Volumes I and II. Royal Botanic Gardens, Kew, UK.

Jalink H, van der Schoor R, Frandas A, van Pijlen, Bino RJ. 1998. Chlorophyll fluorescence of Brassica oleracea seeds as a non-destructive marker for seed maturity and seed performance. Seed Science Research 8:437–443.

Li D-Z, Pritchard HW. 2009. The science and economics of ex situ plant conservation. Trends in Plant Science 14:614–621.

Lin TP, Chen M-H. 1995. Biochemical characteristics associated with the development of the desiccation-sensitive seeds of Machilus thunbergii Sieb. & Zucc. Annals of Botany 76:381–387.

Mondoni A, Probert RJ, Rossi G, Vegini E, Hay FR. 2011. Seeds of alpine plants are short lived: implications for long-term conservation. Annals of Botany 107:171–179.

Pritchard HW, Wood CB, Hodges S, Vautier HJ. 2004. 100-seed test for desiccation tolerance and germination: a case study on eight tropical palm species. Seed Science & Technology 32:393–403.

Probert RJ. 2003. Seed viability under ambient conditions, and the importance of drying. In: Smith RD, Dickie JB, Linington SH, Pritchard HW, Probert RJ, editors. Seed Conservation: Turning Science into Practice. Royal Botanic Gardens, Kew, UK. pp. 337–365.

Probert RJ, Daws MI, Hay FR. 2009. Ecological correlates of ex situ seed longevity: a comparative study on 195 species. Annals of Botany 104:57–69.

Probert RJ, Manger KR, Adams J. 2003. Non-destructive measurement of seed moisture, In: Smith RD, Dickie JB, Linington SH, Pritchard HW, Probert RJ, editors. Seed Conservation: Turning Science into Practice. Royal Botanic Gardens, Kew, UK. pp. 367–387.

Probert R, Adams J, Coneybeer J, Crawford A, Hay F. 2007. Seed quality for conservation is critically affected by pre-storage factors. Australian Journal of Botany 55:326–355.

Sallon S, Solowey E, Cohen Y, Korchinsky R, Egli M, Woodhatch I, Simchoni O, Kislev M. 2008. Germination, genetics, and growth of an ancient date seed. Science 320:1464.

Tuckett RE, Merritt DJ, Hay FR, Hopper SD, Dixon KW. 2010. Comparative longevity and low-temperature storage of seeds of Hydatellaceae and temporary pool species of south-west Australia. Australian Journal of Botany 58:327–334.

Walters C, Wheeler LM, Grotenhuis JM. 2005. Longevity of seeds stored in a genebank: species characteristics. Seed Science Research 15:1–20.

Wood CB, Pritchard HW, Amritiphale D. 2000. Desiccation-induced dormancy in papaya (Carica papaya L.) seeds is alleviated by heat shock. Seed Science Research 10:135–145.

Internet resources

Seed Information Database (SID): http://data.kew.org/sid/

Millennium Seed Bank information sheets 04, 05 and 07: www.kew.org/msbp/scitech/publications/info_sheets.htm

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Chapter 13: Published information resources for plant germplasm collectors

M. Garruccio
Bioversity International, Rome, Italy
E-mail: m.garruccio(at)cgiar.org

This chapter is a synthesis of new knowledge, procedures, best practices and references for collecting plant diversity since the publication of the 1995 volume Collecting Plant Genetic Diversity: Technical Guidelines, edited by Luigi Guarino, V. Ramanatha Rao and Robert Reid, and published by CAB International on behalf of the International Plant Genetic Resources Institute (IPGRI) (now Bioversity International), the Food and Agriculture Organization of the United Nations (FAO), the World Conservation Union (IUCN) and the United Nations Environment Programme (UNEP). The original text for Chapter 13: Bibliographic Databases for Plant Germplasm Collectors, authored by J .A. Dearing and L. Guarino, has been made available online courtesy of CABI. The 2011 update of the Technical Guidelines, edited by L. Guarino, V. Ramanatha Rao and E. Goldberg, has been made available courtesy of Bioversity International.

Please send any comments on this chapter using the Comments feature at the bottom of this page. If you wish to contribute new content or references on the subject please do so here.

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References for this chapter

Abstract

Widespread access to the internet and the technological changes we have seen over the last 16 years, since the first edition of this collecting manual, have dramatically altered the way people access and use information. They have also changed the paradigm of scientific publishing and research. Tools and resources for accessing information on plant genetic resources have grown and evolved from being mainly traditional and paper-based to sophisticated web-based platforms that provide the researcher with many features. Other tools, such as the social media platforms that have recently emerged, allow researchers to connect and collaborate with their peers regardless where they are located in the world. This paper looks at selective trends and movements that have had an impact on the paradigm of scientific publishing and research in the last 16 years, and, within this context, highlight authoritative web-based information resources for those working in the area of plant genetic resources.

Introduction

Sixteen years has passed since the publication of the first edition of Collecting Plant Genetic Diversity : Technical Guidelines. In that time, widespread access to the internet, along with other technological changes, have dramatically altered the way people access and use information. They have also changed the paradigm of scientific publishing and research. Sixteen years ago, a researcher would have primarily consulted hardcopies of abstract journals or standalone databases that were available at a library for his/her research purposes. The completed research would then be disseminated mainly via the medium of publishing in a scientific journal (available only in hardcopy). The same researcher would then meet and collaborate with peers, face to face, at conferences.

This scenario of only 16 years ago is difficult to grasp, when today, searching for information on search engines such as Google has become second nature, as has our ability to access, disseminate and generate information. The internet, today, can allow that same researcher to make his/her work available to the world, anywhere, at any time, in many different formats. It can also allow the researcher the possibility of collaborating with peers on different electronic platforms without leaving his/her desk.

While accessing the internet has now become part of our daily lives, the unprecedented amounts of information a researcher is faced with can be daunting. Together, published and professional web content is estimated to generate about 5 gigabytes/day, whereas user-generated content is created at the rate of about 10 gigabytes/day and growing. (Agichtein et al. 2009). These figures make it eminently clear that filters are required in order to access high-quality, authoritative scientific information. There is also a need to explore the concept that scientific research is now being carried out, communicated and disseminated by social media tools that previously did not exist. The researcher today has the opportunity to access information from many different formats, not just the traditional bibliographic databases that were discussed in the 1995 edition of these technical guidelines.

The two main objectives of this chapter are (1) to look at selective trends and movements that have had an impact on the paradigm of scientific publishing and research in the last 16 years and (2) within this context, to highlight authoritative web-based information resources for those working in the area of plant genetic resources.

Current status

The focus of this chapter is on the main trends and phenomena that have emerged over the last 16 years: (1) using search engines more effectively, (2) open-access resources, (3) social-media tools, (4) bibliographic databases and (5) reference-management systems.

Web searching: how to improve search results

Nowadays most people use the internet for their research purposes, but how effectively? If we are to examine the daunting statistics given to us by Agichtein et al. (2009), we realise that learning how search engines respond to queries can make a significant difference in the results we encounter when searching the web. Learning a few quick shortcuts and tricks can assist the researcher in finding more relevant and targeted information. Most of the major search engines have tutorials and guides on how to improve search results and retrieve relevant information. Table 13.1 provides a good overview of the search engines that are most used and where to locate their on-line tutorials and cheat sheets.

Table 13.1: Web Searching: Improving Your Search Results

This table provides information on where to locate search tips, shortcuts and cheat sheets for the three major search engines currently in use. Learning to use these tips will improve the relevance of research results.

 Note: Access date for this information was 30 June 2011.

Google is the most used search engine. As of December 2010, its market share was 90.57% (StatCounter 2011). Nancy Blachmann from GoogleGuide.com has developed a simple and clear overview of the responses Google will provide depending on how one formulates the query (figure 13.1).

These searching tips can also be used when searching across portals such as Google Scholar, which is one of the major free web search engines that indexes the full text of mainly scholarly literature across an array of disciplines. It allows the researcher to search across many sources (e.g., professional societies, universities, academic publishers) from just one place, and one can view papers and documents either in full text or with a limited preview, depending on the content provider and how much they want their content to be freely available. Google Scholar is one of the first places many researchers refer to when embarking on specific fact-finding.

Figure 13.1: Formulating queries for Google Source: www.googleguide.com. Original can be found at www.googleguide.com/cheatsheet.html.

In some cases, it might also be relevant to search specifically for news items on different PGR-related issues, rather than websites in general. Strategies for doing this are discussed on the Google Books portal.

“Open” information resources: scholarly literature

The movement in scholarly publishing, known as open access, became much more prominent in the 1990s with the advent of the internet. It is a topic that in recent years has become the subject of much discussion among the academic community, funding agencies, government officials and publishers. "By 'open access' …we mean its free availability on the public internet, permitting any users to read, download, copy, distribute, print, search, or link to the full texts of these articles, crawl them for indexing, pass them as data to software, or use them for any other lawful purpose, without financial, legal, or technical barriers other than those inseparable from gaining access to the internet itself” (Suber 2011).

Open-access scientific content is accessed in two primary ways: through open-access repositories (digital collections) where researchers archive or deposit their post-print, or via open-access journals and e-books. While open access was a term hardly heard of 16 years ago, a study carried out by Björk et al. (2010) revealed that 20% of peer-reviewed articles across all disciplines are now freely available over the web, and this figure will continue to grow as authors and their affiliated organizations begin to understand the benefits that open access can bring.

One such benefit is higher citations: open-access papers are more cited than papers that are behind a “payment wall” ( Hajjem and Harnad 2005; Harnad and Brody 2004; Swan 2010). Higher citations important for many universities or research organizations that want to improve their research impact and prestige. Yet, at the same time, content that is open access is often misunderstood, and at times the quality of the science published as open access is seen as somewhat inferior; however, as Swan (n.d.) succinctly states, “Open access is not self-publishing, nor a way to bypass peer-review and formal publication, nor is it a kind of second-class, cut-price publishing route. It is simply the means to make research results freely available online to the whole research community.” In fact, many open-access scientific journals are widely read and have impressive impact factors; the journal PLOS Biology has an impact factor of 12.469 (Thomson Reuters 2011)

There are numerous “open” information resources and platforms that are available on the internet for researchers working in plant genetic resources, where it is possible to access full-text research papers. Content is immediate, online and freely available without the use restrictions commonly imposed by publishers. Another major benefit open access brings is that it has removed the cost barrier for accessing scientific information, particularly for researchers and libraries in developing countries who cannot afford the cost of journal subscriptions. Major open-access resources include journal portals, institutional repositories and e-books. Details about selected resources are outlined in Table 13.2.

Table 13.2: Open-Information Resources: Scholarly Literature

This table outlines the major open-access websites and resources where it is possible to access the full text of research papers, documents and books. The main types of resources found in this table include journal gateways, virtual libraries and repositories. In most cases, content from these websites can be reused, disseminated and copied without requesting permission from the creator.

Social-media tools for researchers

On-line social-media platforms such as blogs, wikis and micro-blogging sites such as Twitter provide a quick, effective means of engaging with other researchers. They have rapidly changed the way science is communicated and disseminated in the last few years, allowing researchers to keep abreast of emerging trends and developments in their respective disciplines.

So what exactly are social media? They are “the use of web-based and mobile technologies to turn communication into interactive dialogue” (Wikipedia 2011a). Most social-media platforms encourage discussion, feedback and sharing of information. Tools such as Twitter, for example, allow a person participating in a conference to write short updates (called tweets) about what is being discussed in real time. The participant’s followers can keep abreast of the conference’s developments wherever they are located in the world, and they are able to respond and interact with the person providing the updates. This type of communication was unimaginable 16 years ago.

The uptake and use of these tools is increasing within the scientific and research community. Why are researchers increasingly using social-media tools? Gruzd and Staves (2011) and prior studies have highlighted three main benefits:

• Researchers need to communicate with their peers, and social media allow them to do this regardless where they are located, at a low cost.

• Social-media platforms provide researchers with the ability to create a community or network of like-minded scholars, which can facilitate and bring together people working on similar research.

• Social media provide the opportunity to expand on ideas or research from the direct interaction between researchers and their readers.

 In addition to Twitter, some of the more popular social-media platforms include wikis and blogs (see table 13.3 for specific links and more details about social-media platforms and tools). The wiki GRIN-Global is a good example of how researchers from different institutions in different locations in the field of plant genetic resources are able to collaborate and work together using social-media tools. Other social-media tools include forums (ScienceForums.Net) and platforms where one can upload and share scientific videos (SciVee), presentations (SlideShare) and images (Flickr). Only time will tell if these existing social-media platforms will be enhanced or even superseded by new technologies; however, the concept and value of “sharing ideas” is an integral part of human nature; consequently, it is difficult to think that social-media platforms will not continue to be part of our working and social domains for many years to come.

Table 13.3: Social Media Tools and Platforms

This table highlights social media websites that encourage scholarly discussion, feedback and sharing of information.

Bibliographical databases

Bibliographical databases are, and have always been, important tools for conducting research. With the advent of the internet, many of the bibliographic databases that were featured in the 1995 edition of the Technical Guidelines have remodelled themselves from standalone databases to web-based digital libraries. Often, these databases not only provide the full text to indexed and abstracted content, but also often provide the researcher with tools for analysis and are capable of carrying out federated searches across data silos. A federated search is an information-retrieval technology that allows the simultaneous search of multiple searchable resources. A user makes a single query request, which is distributed to the search engines participating in the federation. The federated search then aggregates the results that are received from the search engines for presentation to the user (Wikipedia 2011b).

These platforms are always in constant evolution and are consistently improving and extending content, search features and support tools. Table 13.4 provides a listing of the main bibliographic databases for agriculture and plant science, which will be useful to a researcher working in plant genetic resources.

Table 13.4: Agricultural Bibliographic Databases

This table highlights the main bibliographic databases that cover agriculture, PGR and the life sciences.

Reference-management tools

With the huge amount of information and data available over the internet, researchers often struggle with how to manage the information they gather from databases and websites, as well as blogs and forums. Web-based reference-management systems can be the answer to this dilemma.

Reference-management software assists researchers and authors in managing the many bibliographic references they may have accumulated over time. The software is usually a database that allows for the creation of bibliographies and also acts as a personal online library. It has been around for many years, and with the advent of the internet, reference-management applications, like bibliographic databases, have evolved tremendously. From being databases installed on a stand-alone personal computer, these web-based platforms now have many features and tools. Apart from the traditional feature of generating bibliographies, today’s reference-management systems also possess social-networking elements, research catalogues, drag-and-drop features to reduce manual data inputting, and mobile applications for smart-phones and iPads. Some systems also allow users to save not only documents but also screenshots of web pages so that they have the ability to come back to the webpage at a later time. A growing number of reference-management systems are free over the web and can be of great benefit to researchers struggling to come to terms with the amount of information or data they have accumulated. Wikipedia (2011c) has a good article on reference management systems where it compares 29 systems (both free and proprietary). This information has been reproduced in part in table 13.5, which has a selection of the better known systems.

Table 13.5: Bibliographic Reference-Management Systems

Bibliographic reference-management systems are excellent tools for managing references and generating bibliographies and citations when writing research papers.

 Source: Wikipedia (2011c).

Future challenges/gaps/needs

In this chapter, we have looked at information tools and resources that can assist the researcher in the PGR domain. We have seen how a researcher can use many different platforms for resource discovery, and we have highlighted different formats/platforms that one can use to disseminate and generate content. All of these tools and resources will continue to evolve, change or be superseded by new technology, which ultimately means that researchers also need to keep abreast of how scientific information is generated and disseminated. Currently, a lot of focus has been given to mobile technology, where one can access information from smartphones or iPads and download applications that permit one to do an array of things, such as data analysis or creating tables. Tools such as these allow information to be generated and disseminated in a timely fashion; researchers do not need to wait until they are back at their desks. These tools have changed, and will continue to change, the way science is carried out, and it is to the researcher’s advantage to be aware of their availability and features.

As the scientific world moves more and more into the digital realm, one of the challenges researchers and their respective organizational libraries need to address is that a lot of scientific information is available only through subscription-based avenues. With the advent of digital information, a subscription often means that one is purchasing access to content but not the actual content, per se, as is the case with paper subscriptions, where one would put the journal on the shelf for as long as necessary. Company takeovers, for example, could affect access to digital information. Negotiations with publishers for perpetual access is necessary in order to retain access to content.

Another factor to contemplate is the gap in knowledge that exists between researchers from the South and those from the North. As Schisler (2011) states, “The digital divide is something we must not dismiss when considering the fact that anyone can now publish. The digital divide represents the socioeconomic difference among communities in their access to computers and the Internet. It is also about the required knowledge needed to use the hardware and software, the quality of these devices and connections, and the differences of literacy and technical skills between communities and countries…. When we think of the World Wide Web, as of today, it does not yet encompass the entire world. Many of the countries on the African continent, for example, have less than 5 Internet users per 100 inhabitants as opposed to the richer countries in the world that have over 50 Internet users per 100 inhabitants. We are seeing a small but decreasing gap in this divide, and this trend will continue.” Not everyone has the access to information that is taken for granted in many developed countries, and while the knowledge gap may be decreasing, it is still very evident in many developing countries. While addressing the question of how to overcome the complex issue of the digital divide is not the author’s intention, it is important to remind ourselves of the situation that is present today.

Conclusions

The last sixteen years has seen monumental changes in the way scholarly information is accessed, retrieved and re-used. As a result, the paradigm of scholarly publishing, communication and collaboration has changed dramatically since 1995 and it has provided the opportunity to bring the scientific community together in ways that before seemed impossible. This chapter has attempted to bring to the fore some of the most useful and pertinent resources for researchers working in the domain of plant genetic resources and to highlight some of the challenges, gaps and needs that could affect them or their respective organizations. The websites and research tools highlighted here will hopefully provide researchers with relevant and timely information, allow them to connect with their peers, and provide some respite from the “information overload” that one encounters when searching across the internet.

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References and further reading

Agichtein E, Gabrilovich E, Zha H. 2009. The social future of web search: modeling, exploiting, and searching collaboratively generated content. IEEE Data Engineering Bulletin 32(4):1–10. Available on-line (accessed 20 September 2011): http://sites.computer.org/debull/A09June/agichtein_ssm1.pdf .

Björk B-C, Welling P, Laakso M, Majlender P, Hedlund T, Guðnason G. 2010. Open access to the scientific journal literature: situation 2009. PLoS ONE 5(6): e11273/journal.pone.0011273. Available on-line (accessed 20 September 2011): www.plosone.org/article/info:doi/10.1371/journal.pone.0011273.

Gruzd A, Staves K. 2011. Trends in scholarly use of on-line social media. Academia.edu. Available on-line (accessed 20 September 2011): http://dal.academia.edu/AnatoliyGruzd/Papers/514997/Trends_in_scholarly_use_of_online_social_media.

Hajjem C, Harnad S, Gingras Y. 2005. Ten-year cross-disciplinary comparison of the growth of open access and how it increases research citation impact. IEEE Data Engineering Bulletin 28(4):39–47. Available on-line (accessed 20 September 2011): http://sites.computer.org/debull/A05dec/hajjem.pdf.

Harnad S, Brody T. 2004. Comparing the impact of open access (OA) vs. non-OA articles in the same journals. D-Lib Magazine 10(6). Available on-line (accessed 20 September 2011): www.dlib.org/dlib/june04/harnad/06harnad.html.

Schisler M. 2011. The future of publishing – introduction. Online Encyclopedia, Net Industries. Available on-line (accessed 18 August 2011): http://encyclopedia.jrank.org/articles/pages/1088/The-Future-of-Publishing.html.

StatCounter. 2011. Top 5 search engines from Oct to Dec 10. StatCounter Global Stats. Available on-line (accessed 29 July 2011): http://gs.statcounter.com/#browser-ww-monthly-201010-201012.

Suber P. 2011. Budapest open access initiative: frequently asked questions. Earlham College, Richmond, IN, USA. Available on-line (accessed 29 July 2011): www.earlham.edu/~peters/fos/boaifaq.htm#openaccess.

Swan A. 2010. The open access citation advantage: studies and results to date. School of Electronics & Computer Science, University of Southampton, UK. Available on-line (accessed 20 September 2011): http://eprints.ecs.soton.ac.uk/18516/1/Citation_advantage_paper.docx.

Swan A. n.d. Open access: a briefing paper for research managers and administrators. EnablingOpenScholarship, Liege, Belgium. Available on-line (accessed 20 September 2011): www.openscholarship.org/upload/docs/application/pdf/2009-01/briefing_paper_open_access.pdf.

Thomson Reuters. 2011. Journal Citation Reports 2010. Thomson Reuters, New York. See http://thomsonreuters.com/products_services/science/science_products/a-z/journal_citation_reports/.

Wikipedia. 2011a. Social media. Available on-line (accessed 19 September 2011): http://en.wikipedia.org/wiki/Social_media.

Wikipedia. 2011b. Federated search. Available on-line (accessed 25 August 2011): http://en.wikipedia.org/wiki/Federated_search.

Wikipedia. 2011c. Comparison of reference management software. Available on-line (accessed 28 July 2011: http://en.wikipedia.org/wiki/Comparison_of_reference_management_software.

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Chapter 10: Published sources of information on wild plant species

I. Thormann
Bioversity International, Rome, Italy
E-mail: i.thormann(at)cgiar.org

This chapter is a synthesis of new knowledge, procedures, best practices and references for collecting plant diversity since the publication of the 1995 volume Collecting Plant Genetic Diversity: Technical Guidelines, edited by Luigi Guarino, V. Ramanatha Rao and Robert Reid, and published by CAB International on behalf of the International Plant Genetic Resources Institute (IPGRI) (now Bioversity International), the Food and Agriculture Organization of the United Nations (FAO), the World Conservation Union (IUCN) and the United Nations Environment Programme (UNEP). The original text for Chapter 10: Published Sources of Information on Wild Plant Species, authored by H. D. V. Prendergast, has been made available online courtesy of CABI. The 2011 update of the Technical Guidelines, edited by L. Guarino, V. Ramanatha Rao and E. Goldberg, has been made available courtesy of Bioversity International.

Please send any comments on this chapter using the Comments feature at the bottom of this page. If you wish to contribute new content or references on the subject please do so here.

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References for this chapter

Internet resources for this chapter

	Screen shot from eFloras web site (3 Oct. 2011, www.efloras.org)

Abstract

Chapter 10 of the 1995 edition of the Technical Guidelines provided key works and extensive lists of references useful to collectors for locating and recognizing the plants they would go out to collect. The methodology provided in 1995 suggested using the information provided as a guide to more specific publications. This approach to obtaining published information has changed with the advent of the internet, which has become a fast and primary means of locating and accessing relevant resources. Many of the key works listed in 1995 have kept pace with the development of information technology and have become available online. This revision of chapter 10 provides an update of key works and floras, including their online availability, as well as links to other relevant resources.

Introduction

Germplasm collectors need to locate and recognize the material they are going to collect. This requires them to be able to identify plants, to determine their accepted botanical name and to have knowledge about where they grow. In the first version of the Technical Guidelines, the aim of this chapter, on published sources of information on wild plant species, had been to support collectors in this regard by providing a guide to the world

• taxonomic literature on vascular (especially flowering) plants

• ecological literature on vascular (especially flowering) plants

• literature on identification of seeds and fruits

It focused on printed literature and described a methodology that should lead to relevant and necessary resources for researchers planning to collect wild species.

The methodology started with some key works, considered “essential to every collector and which act as „signposts‟ to the rest of the relevant botanical literature”, and was supported by listing large-scale floristic, ecological and bibliographic works. The collector was supposed to identify from these basic publications other more specific and focused literature. In order to reduce the literature to a manageable but effective minimum, only major works were included in the lists, and publications referring to just one country or one group of plants were excluded. They should be easily located via the key works listed. Today the quantity of published resources as further increased, but given the advent of the internet, it has become much easier and faster to locate resources. Any reference to publications specific to a country or plant group, or the publication itself, can today be retrieved through a targeted internet search. The right combination of search terms typed into the search box of an internet browser can immediately yield important information.

A methodology to retrieve published information on wild species today would therefore include the internet as an essential resource: any search would most likely start with a search on the internet. Publications that would need to be acquired in hard copy can easily be ordered through online bookshops, so the list of international book sellers has not been updated for this revised version of chapter 10.

The key works provided by Prendergast in the 1995 chapter, however, have not lost their importance. Some have been updated, and in many cases their accessibility and availability has increased as they have become available online.

A similar statement can be made for databases. While the 1995 chapter included a list of databases on plant diversity that were being developed in a variety of countries and organizations, none of them were available online at that time. Since then, the quantity and availability of databases featuring relevant data for collectors has grown considerably.
The current status and availability of the key works listed by Prendergast is provided below, illustrating how availability and accessibility has changed. Reference is also made to the other lists of publications from the earlier work.

Current status

Key works

Experts

The assertion made in 1995 (that contacting an expert on the flora and the area to be explored might provide quicker answers than consulting the literature) remains valid today. Although a literature search is much faster and easier today than it was in 1995, given the availability of the internet, the quantity of information available and to be screened has grown considerably, so targeted questions to experts can still save time – and experts are now much easier to find and contact through the internet.

The first key works listed are the 8th edition of the Index Herbariorum (Holmgren et al. 1990) and the Plant Specialist Index (Holmgren and Holmgren 1992), as these provided not only information about herbaria, but also about experts. The number of herbaria has grown considerably since 1995 (from 2,639 to nearly 4000) and so have the staff (from 7,627 to about 10,000), according to http://sciweb.nybg.org/science2/IndexHerbariorum.asp (accessed 2 February 2011).

The importance of these references has not changed, but the way of updating and presenting them to the public has kept pace with technology. There is no new hard-copy version of the Index Herbariorum but the whole Index as well as the Plant Specialist Index have been transferred to a database – “Index Herbariorum: A Global Directory of Public Herbaria and Associated Staff” – which is hosted and edited by the New York Botanical Garden and continuously updated. As the Index is fully searchable by research specialty, it also serves as a plant specialist index. The summary that Prendergast provides in 1995 about the usefulness of a search in the index and the help it can provide is still valid.

Today, experts can also be identified by visiting the websites of organizations that either work in the target area on environmental, conservation and related issues or that specialize in the species that the collector is targeting. Websites focusing on specific groups of species often contain lists of experts. Some relevant examples for collectors of wild plant are mentioned here.
The Crop Wild Relatives Global Portal (www.cropwildrelatives.org) provides names and contact details of experts as well as institutions working with crop wild relatives (CWR). Crops for the Future (www.cropsforthefuture.org/?page_id=514) has a database of the research interests of over 300 underutilized plant experts globally. Conservation organizations, as well, can provide the names of specialists or can be contacted to ask for specialists. The Species Survival Commission (SSC) of the International Union for Conservation of Nature (IUCN) has created targeted species list groups (www.iucn.org/about/work/programmes/species/about_ssc/specialist_groups/directory_specialist_groups/directory_sg_plants): 29 plant specialist groups exist, which cover either a country or a region (e.g., Cuba or Southern Africa) or a group of species (e.g., CWR, orchids or trees). Contact details for all specialist groups and, if existent, the respective specialist group website are currently provided on the IUCN-SSC web page. One group that is relevant to collectors of wild plants is the Crop Wild Relative Specialist Group (www.cwrsg.org/index.asp).

Checking taxonomy/species names

Prendergast cites the Index Kewensis as an authoritative resource for checking the taxonomy of species (collectors should be aware of the description of new species or changes in names of species). The importance of the Index has not changed; rather, its usefulness has increased, building on progress in information technology, creating the International Plant Name Index (IPNI) (www.ipni.org/index.html) by combining the Index Kewensis with the Gray Index (originally the Gray Herbarium Card Index) and the Australian Plant Names Index into the most comprehensive listing of plant names available today and searchable online. The Gray Index includes names for New World taxa published on or after January 1886 and has provided over 350,000 records to IPNI. The Australian Plant Names Index has contributed over 63,000 records, compiled since 1973 and including all scientific names used in the literature for Australian vascular plants. IPNI is a database of names and associated basic bibliographical details of seed plants, ferns and lycophytes. Its goal is to eliminate the need for repeated reference to primary sources for basic bibliographic information about plant names.

Other websites where species names and synonyms can be looked up have become available, and while they often provide additional information, they usually do not provide the publication place of species names as IPNI does. Some examples are provided below.

• Catalogue of Life (CoL) (www.catalogueoflife.org/annual-checklist): The goal is to create a validated checklist of the entire world's species (plants, animals, fungi and microbes) by bringing together an array of global species databases covering each of the major groups of organisms. It is jointly produced by Species2000 and the Integrated Taxonomic Information system (ITIS) of North America and is available as an annual checklist. A search in the list provides the accepted taxon name, synonyms, the classification and, if available in the source database, common names, distribution, online resources, additional data.

• GRIN is the Genetic Resources Information Network of the United States Department of Agriculture (USDA) (www.ars-grin.gov/cgi-bin/npgs/html/tax_search.pl?). Together with the accepted name taxonomy, it also provides synonyms, common names, distributional range, economic importance, references and links to other web resources. It covers nearly 95,000 species or infraspecies.

• TROPICOS (www.tropicos.org) is the online database of the Missouri Botanical Garden in the USA. All of the nomenclatural, bibliographic and specimen data accumulated in their electronic databases over the past 25 years are publicly available here. The system has over 1.2 million scientific names and 3.9 million specimen records.

• The African Plant Database (www.ville-ge.ch/musinfo/bd/cjb/africa/recherche.php) currently comprises 186,948 names of African plants with their nomenclatural status.

• The current version 1 of The Plant List (www.theplantlist.org) provides the accepted Latin name for most plant species covered, with links to all synonyms by which that species has been known. It also includes unresolved names for which the contributing data sources did not contain sufficient evidence to decide whether they were accepted names or synonyms. This resource has been developed through collaboration between the Royal Botanic Gardens, Kew, and the Missouri Botanical Garden.

Other important taxonomy-related general references have become available through the internet:

• The International Code of Botanical Nomenclature (http://ibot.sav.sk/icbn/main.htm) is now available.

• The Index Nominum Genericorum (ING) (http://botany.si.edu/ing) is a compilation of generic names published for organisms covered by the International Code of Botanical Nomenclature.

• The Linnaean Plant Name Typification Project (www.nhm.ac.uk/research-curation/research/projects/linnaean-typification/databasehome.html) offers a database containing typification details for all Linnaean plant names. The place of publication is provided for each binomial, along with stated provenance, the type specimen (or illustration), a reference to where the type choice was published, and an indication of the current name of the taxon within which Linnaeus' original binomial now falls (binomial and family names).

• “Vascular Plant Families and Genera”, compiled by R. K. Brummitt and published by the Royal Botanic Gardens, Kew, in 1992, is now available as an online database: http://data.kew.org/vpfg1992/vascplnt.html.

Two reference books cited by Prendergast that still need to be consulted as books are Cronquist‟s “The Evolution and Classification of Flowering Plants” and Mabberley‟s “The Plant-book”.

Digitized botanical literature

The Kew record of taxonomic literature, later the Kew Record (http://kbd.kew.org/kbd/searchpage.do), has also become searchable online and is no longer published as hard copy. Kew‟s bibliographic database on economic botany and plant micromorphology can be searched through the same interface. Individual countries can easily be scanned for botanical publications, which can help to identify relevant books and journal articles for specific regions. For more details about the importance and use of this resource, please refer to the 1995 edition of this chapter.

There are other online sources of digitized botanical literature, such as the Biodiversity Heritage Library (BHL) (www.biodiversitylibrary.org), which is a consortium of 12 natural history and botanical libraries. And single botanic gardens and herbaria have started to provide online access to their resources. Examples are the Missouri Botanic Garden‟s Botanicus (www.botanicus.org) or the Real Jardín Botánico in Madrid, Spain (http://bibdigital.rjb.csic.es/ing/index.php).

Another key publication “Plants in Danger: What Do We Know?” (Davis et al. 1986) covers all countries of the world and is now available in full text online (www.archive.org/stream/plantsindangerwh86davi/plantsindangerwh86davi_djvu.txt).

Floras

An updated edition of Frodin‟s “Guide to Standard Floras of the World”, which is mentioned in the 1995 edition of the Technical Guidelines as an indispensable source, was published in June 2001 and is available online (http://assets.cambridge.org/97805217/90772/sample/9780521790772ws.pdf). It is considered the standard listing of known Floras and ongoing Flora projects, with an annotated, geographical, systematic bibliography of the principal Floras, as well as enumerations, checklists and chronological atlases of different areas.

The number of Floras available online is increasing, and they are often more than a simple checklist and include identification keys. Many Floras, catalogues and checklists of plant species are based on a geographic region or a species group (mostly family). However, they provide varying levels of detail, from simply the nomenclature, through nomenclature and distribution to the detailed description usually contained in a Flora. Photo guides to plants are also becoming available online, such as the photo guide to West African plants (www.westafricanplants.senckenberg.de/root/index.php).

The TROPICOS database provides a series of 28 projects (www.tropicos.org/ProjectList.aspx) where links are provided to single online checklists, catalogues and Floras (including keys for identification) of several plant families and countries or regions. Some of them are integrated in the website of eFloras (www.eFloras.org), which provides access to 10 floras and 4 checklists (www.efloras.org). See Brach and Song (2006) for a description.

Table 10.1 contains checklists and Floras for specific countries or regions, and table 10.2 lists Floras for specific groups of plants. They have either been extracted from the websites listed above or found through internet searches. The list also contains those floras listed by Prendergast that have become available online since the publication of this chapter in 1995. These lists are not intended to be complete and it is expected that more Floras will become available online in the future.

Table 10.1: Checklists and Floras Available Online for Specific Countries or Regions

 Ecological key works

The two outstanding works mentioned by Prendergast in this section in the original chapter have neither been updated nor revised, but they are still valid as references. These are Takhtajan (1986) “Floristic Regions of the World” and White (1983) “The Vegetation of Africa”.

The list of the 35 floristic regions provided by Takhtajan and their subdivisions into a total of 152 floristic provinces can be viewed on Wikipedia (http://en.wikipedia.org/wiki/Phytochorion). Some of the provinces already have links to more detailed descriptions.

White‟s “Vegetation of Africa” was written to accompany the UNESCO vegetation map of Africa. A very extensive checklist of online vegetation and plant distribution maps (http://cluster3.lib.berkeley.edu/EART/vegmaps.html), developed by the library of the University of California, Berkeley, can be found online.

Table 10.2: Checklists and Floras Available Online for Specific Plant Groups

Centres of plant diversity, protected areas and conservation status

All volumes of the “Centres of Plant Diversity” have now been published, and the information for the Americas is available online (http://botany.si.edu/projects/cpd/about_project.htm).

There are many different types of protected, designated and recognized areas of biodiversity, and there are many varied terms used to refer to them. The A to Z Areas of Biodiversity Importance (www.biodiversitya-z.org) provides clear, concise and relevant information about each type of area.

The most comprehensive dataset on protected areas is provided through the Word Database of Protected Areas (WDPA) (www.wdpa.org).

The “World Plant Conservation Bibliography”, published in 1990 by the World Conservation Monitoring Centre (WCMC) and the Royal Botanic Garden, Kew, is available online (www.archive.org/details/worldplantconser90wcmc). Many more publications have become available since the publication of that bibliography, but no similar effort has been made to compile more recent publications. Here again, a search on the internet or in targeted bibliographic databases (see chapter 13) is the best start to obtaining literature concerning conservation issues and the status of a target species or region.

The threat status of a species might be verified through a search in the International Union for Conservation of Nature (IUCN) red list of threatened species (www.iucnredlist.org).

Today there are global databases that provide data to help understand and map the distribution and ex situ conservation status of target species. Two examples are the Global Biodiversity Information Facility (GBIF) data portal (http://data.gbif.org/welcome.htm;jsessionid=5D1EA90E4AC94B68C5A78D24C326A35E) and GENESYS (www.genesys-pgr.org).

Ecological works, botanic bibliographies and fruit & seed identification

The ecological works listed in the 1995 version of this chapter are still valid references and starting points. Additional ecological works might have become available since then and others might have been updated. The reader can easily verify this through an internet search. Online availability can also be quickly verified through a simple internet search for the title of the publication.

Because bibliographies get outdated much more quickly than ecological works, a specific search will be necessary to get an overview of publications published during the past 20 years. However, the bibliographies cited in the 1995 version of this chapter provide references to important baseline publications and can serve as a way to understand how thoroughly a region has been studied.

Seed identification aids are becoming available online. The first two hits when searching for seed identification are “Seed Identification and How to Identify Seeds” (www.seedimages.com/seed-identification/seed-identification.html), from Colorado State University, and the Arable Seed Identification System (ASIS) (http://asis.scri.ac.uk) developed by the Scottish Crop Research Institute.

Conclusions

The advent of the internet has completely changed the ways and possibilities of obtaining information, and it has become the first choice for searching for information and data. The fact that many of the botanical key works have become online resources that are freely available for consultation and search confirms their continued relevance and illustrates the importance of the internet as a means to publish and search for data.

The lists of online resources provided in this update are by no means comprehensive, as new resources are becoming available every day. Nearly every website has a page with relevant and related links to other websites, which can guide the user to additional resources.

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References and further reading

Brach AR, Song H. 2006. eFloras: New directions for online floras exemplified by the Flora of China Project. Taxon 55(1):188–192.

Brummitt RK. 1992. Vascular Plant Families and Genera. The Royal Botanic Gardens, Kew, UK. Available online (accessed 25 September 2011): http://data.kew.org/vpfg1992/vascplnt.html.

Cronquist A. 1988. The Evolution and Classification of Flowering Plants. New York Botanical Garden, New York.

Davis SD, Droop SJM, Gregerson P, Henson L, Leon CJ, Villa-Lobos JL, Synge H, Zantovska JA. 1986. Plants in Danger: What Do We Know? International Union for Conservation of Nature and Natural Resources, Gland, Switzerland. Available online (accessed 26 July 2011): www.archive.org/stream/plantsindangerwh86davi/plantsindangerwh86davi_djvu.txt.

Frodin DG. 2001. Standard Floras of the World. 2nd edition. Cambridge University Press, Cambridge, UK. Available online (accessed 23 May 2011): http://assets.cambridge.org/97805217/90772/sample/9780521790772ws.pdf.

Holmgren PK, Holmgren NH. 1992. Plant specialists index. Regnum Vegetabile 124:1–394.

Holmgren NH, Holmgren PK, Barnett LC (eds). 1990. Index Herbariorum. New York Botanical Garden, New York.

Mabberley DJ. 1989. The Plant-Book: A Portable Dictionary of the Higher Plants. Cambridge University Press, Cambridge, UK.

Takhtajan A. 1986. Floristic Regions of the World. (Translated by TJ Crovello). California University Press, Berkeley.

Thiers, B. [continuously updated]. Index Herbariorum. New York Botanical Garden's Virtual Herbarium. http://sweetgum.nybg.org/ih

White F. 1983. The Vegetation of Africa: A Descriptive Memoir to Accompany the UNESCO/AETFATIUNSO Vegetation Map of Africa. UNESCO, Paris.

Internet resources

A to Z Areas of Biodiversity Importance: www.biodiversitya-z.org

African Plant Database: www.ville-ge.ch/musinfo/bd/cjb/africa/recherche.php

Arable Seed Identification System (ASIS): http://asis.scri.ac.uk

Biodiversity Heritage Library (BHL): www.biodiversitylibrary.org

Catalogue of Life (CoL): www.catalogueoflife.org/annual-checklist

Centres of Plant Diversity, the Americas: http://botany.si.edu/projects/cpd/about_project.htm

Checklist of Online Vegetation and Plant Distribution Maps: http://cluster3.lib.berkeley.edu/EART/vegmaps.html

Crop Wild Relatives Global Portal: www.cropwildrelatives.org

Crop Wild Relative Specialist Group: http://www.cwrsg.org/index.asp

Crops for the Future: www.cropsforthefuture.org/?page_id=514

eFloras: www.eFloras.org

GENESYS: www.genesys-pgr.org

Genetic Resources Information Network (GRIN) of the United States Department of Agriculture (USDA): www.ars-grin.gov/cgi-bin/npgs/html/tax_search.pl?

Global Biodiversity Information Facility (GBIF): http://data.gbif.org/welcome.htm;jsessionid=5D1EA90E4AC94B68C5A78D24C326A35E

Index Herbariorum (a global directory of public herbaria and associated staff): http://sciweb.nybg.org/science2/IndexHerbariorum.asp

Index Nominum Genericorum (ING): http://botany.si.edu/ing

International Code of Botanical Nomenclature: http://ibot.sav.sk/icbn/main.htm

International Plant Name Index (IPNI): www.ipni.org/index.html

IUCN Red List of Threatened Species: www.iucnredlist.org

Kew Record: http://kbd.kew.org/kbd/searchpage.do

Linnaean Plant Name Typification Project: www.nhm.ac.uk/research-curation/research/projects/linnaean-typification/databasehome.html

Photo guide to West African plants: www.westafricanplants.senckenberg.de/root/index.php

Real Jardín Botánico: http://bibdigital.rjb.csic.es/ing/index.php

Seed Identification and How to Identify Seeds: www.seedimages.com/seed-identification/seed-identification.html

Target species list groups of the Species Survival Commission (SSC) of the International Union for Conservation of Nature (IUCN): www.iucn.org/about/work/programmes/species/about_ssc/specialist_groups/directory_specialist_groups/directory_sg_plants

The Plant List: www.theplantlist.org

TROPICOS, online database of the Missouri Botanical Garden: www.tropicos.org

Vascular Plant Families and Genera (compiled by RK Brummitt, published by the Royal Botanic Gardens, Kew, 1992): http://data.kew.org/vpfg1992/vascplnt.html

World Plant Conservation Bibliography: www.archive.org/details/worldplantconser90wcmc

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