Registration of cassava genetic resources
Contributors to this page: CIAT, Colombia (Daniel Debouck); IITA, Nigeria (Dominique Dumet); Bioversity International/ILRI, Ethiopia (Alexandra Jorge); independent consultant (Clair Hershey); INIA, Peru (Llerme Rios).
This section covers registration of cassava and Manihot wild species that are being newly introduced into a genebank. These genetic resources may be introduced as stakes (stem pieces) (within-country only), as in vitro material or as seeds. Wild species are typically introduced as seed samples from a population, while cassava is generally introduced as clonal material, where each accession is genetically uniform.
Verifying accompanying documentation
The following documentation should be sent with the new material
For all accessions:
- Origin and contact person.
- List of shipped accessions.
- Date of preparation of material and date of shipment.
- Details of treatments and growth conditions (e.g. in vitro media specifications).
- Post-arrival handling instructions.
For accessions imported from another country (in addition to above):
- Import permit issued by the recipient country.
- Standard Material Transfer Agreement (SMTA), modelled upon the specifications of the International Treaty for Plant Genetic Resources for Food and Agriculture (ITPGRFA).
- Phytosanitary Certificate issued by the official phytosanitary authority of the donor country.
Verifying the consignment
Inspection of plants to determine any plant health problems should include the following:
- Visual inspection for fungi and bacteria.
- Virus indexing of material (see plant health section for more details).
- If any pathogens are detected, material should be destroyed.
- If the germplasm is rare, material may be retained, but the pathogens should be eliminated using high-confidence techniques before introducing the material into the genebank.
The introduction of cassava or Manihot material at the beginning of the conservation process can usually be accomplished in one of three different forms:
- From planting material (cuttings). These usually originate from within-country collections.
- From in vitro material. These can be from within-country or foreign collections.
- From botanic seeds, especially, in the case of wild species. Plants may need to be regenerated from embryo rescue if conventional germination fails.
Regardless of the form of introduction, a ‘temporary identifier’ must be assigned to each individual sample of the new accession until it is decided which sample, or set of derived sub-samples, will be included in the genebank and registered officially.
- This temporary identifier usually consists of the accession’s name and code, as provided by the donor, and a sample number (e.g. a serial number such as 1, 2, 3) assigned at the receiving genebank.
The official registration involves the attribution of a permanent and unique identifier code. In the case of tissue culture introductions, an accession can be officially registered once the following conditions are met:
- Tissue cultures derived from one single sample (shoot tip) are tested aseptic (i.e. free of contaminating fungi and bacteria).
- A minimal number (generally about seven) of vigorously growing tissue cultures derived from the selected sample are established.
If the conditions described above cannot be met, then a temporary accession number must be assigned and plantlets must go through the necessary disease cleaning or multiplication process until they can be assigned a permanent number.
A step by step general guideline for registration can be seen by clicking here.
Recording information during registration
New material - introduction phase
Newly introduced meristems or nodal cuttings are often processed in batches. For each batch, a series of information should be recorded in a table with the following fields (example from IITA):
- Batch number.
- Accession number (may be a number or a combination of letters and numbers).
- Date of in vitro introduction.
- Number of explants introduced.
- Numbers of plantlets sent to multiplication 1.
- Contamination while in multiplication 1.
- Necrosis while in multiplication 1.
- Number of plantlets sent to the genebank.
On-going material - germplasm already in the genebank
Once an accession is already introduced in the bank, its permanent accession number should be added to the database. For each accession the following data should be recorded (example below is from IITA; the details of this sequence will vary according to the needs and procedures of each specific genebank):
- Accession number.
- Date of introduction in vitro (in case of replacement, all previous entries should be discarded). Type of explant (meristem/nodal cutting/other).
- Virus-free lines certified (yes/no).
- In the bank at the time of last inventory (insert date of last inventory).
- In subculture at the time of last inventory (insert date of last inventory).
- Current number of replicates in subculture.
- Total replicates (= in the bank + in subculture).
- Contamination in bank (number of tubes eliminated because of contamination).
- Necrosis in bank (number of tubes eliminated because of necrosis).
- Out 1 (number of tubes sent to subculture 1).
- Date out 1 (date of subculture 1).
- Obtained 1 (number of micro-cuttings obtained after subculture 1).
- Out 2 (number of tubes sent to subculture 2).
- Date out 2 (date of subculture 2).
- Obtained 2 (number of micro-cuttings obtained after subculture 2).
- Current number of replicates in subculture.
- Subcontamination (number of tubes eliminated from subculture due to contamination).
- Subnecrosis (number of tubes eliminated from subculture due to necrosis).
- Back 1 to bank (number of tubes sent back to the bank from subculture 1).
- Date back 1 (date when subculture 1 is sent back to the bank).
- Back 2 to bank (number of tubes sent back to the bank from subculture 2).
- Date back 2 (date when subculture 2 is sent back to the bank).
- Old cuttings discarded (number of cuttings in the bank discarded during replacement).
- Extra subcultures discarded (tubes from subculture discarded).
- Nodal cutting from the bank sent to acclimatization, other experiments, safe duplication or for multiplication and distribution.
- Computerization of all the data is advisable to facilitate germplasm management. The use of portable data recorders speeds up data collection and reduces recording mistakes. Ultimately, barcoding in vitro collections can further improve genebank management in terms of cost and data reliability.
- Establishing and maintaining a documentation system to record and manage all relevant information related to the introduction of material, for further reference. A database system is usually recommended when possible.
- Germplasm inventory. An inventory of all germplasm should be performed once a year.
References and further reading
Ceballos H. 2006. Cassava research at CIAT [poster]. Centro Internacional de Agricultura Tropical (CIAT), Cali, Colombia. Available from: http://webapp.ciat.cgiar.org/news/pdf/poster02_scmeeting_06.pdf. Date accessed: 26 August 2010.
Guevara CL, Mafla G. 1996. Manihot collections held at CIAT. In: Engelmann F, editor. Management of field and in vitro germplasm collections. CIAT, Cali, Colombia. pp. 109-112.
Mafla G, Roa JC, Debouck DG. 2004. Observations about the distribution of cassava germplasm from an international collection. Poster presented at the CBN-V. Available from: http://ciat-library.ciat.cgiar.org/Articulos_Ciat/CBN-V.%20G%20Mafla%20ppt.pdf. Date accessed: 26 August 2010.
Mafla G, Roa JC, Flor NC, Aranzales E, Debouck DG. 2006. Distribution of cassava germplasm from an international genebank: a service to the global agriculture. Poster presented at the First meeting of the Governing Body, ITPGRFA, Madrid, Spain, 12-16 June 2006. Available from: http://ciat-library.ciat.cgiar.org/Articulos_Ciat/CIAT40years.pdf. Date accessed: 26 August 2010.