Yam genetic resources conserved at IITA

Badara Gueye (B.Gueye@cgiar.org) and Michael Abberton

Within CGIAR, IITA has the mandate for the collection, characterization, and exchange of yam species. IITA’s Genetic Resources Center (GRC) thus holds a major yam international germplasm collection in trust under the Multilateral System of the International Treaty on Plant Genetic Resources for Food and Agriculture (ITPGRFA).

With 3,872 accessions, the IITA yam collection is the world’s largest, including nine of the major cultivated species: Dioscorea rotundata, D. alata, D. bulbifera, D. cayenensis, D. dumentorum, D. esculenta, D. preussii, D. manganotiana, and D. praehensilis. Conserved in the field and through an in vitro genebank, it represents a large genepool for yam crop improvement to help the crop reach its full potential for food and income for poor farmers. To meet this objective, GRC is working on many themes for harnessing yam genetic resources in collaboration with a range of partners. The first one is the filling of genetic gaps to ensure the availability of a broader yam gene pool. In 2014, we are carrying out germplasm collection in Nigeria and Benin Republic. The entire yam collection is conserved in the IITA field bank at Ibadan, Nigeria, and the use of outstation sites offers different conditions for the regeneration of recalcitrant lines, which reduces germplasm losses. More than one-third of the yam collection is duplicated in the in vitro medium-term storage facility at IITA-Ibadan. The development of a yam cryopreservation protocol will allow long-term conservation.

To promote the use and distribution of yam germplasm, especially in breeding, the entire yam collection was characterized using agromorphological descriptors, leading to the identification of a core collection. Increasing collaboration with the yam breeders, germplasm health specialists, and national partners is ongoing to carry out genetic resources evaluation including for market demanded traits. Molecular tools and advanced phenotyping methods are also being employed to further characterize the germplasm and further promote its use. All the data are made available and accessible worldwide and efforts are ongoing to increase the proportion of quarantine pathogen free yam genetic resources for more distribution across borders. Viruses are important pathogens of yam, therefore germplasm use will also be promoted through production of virus-free material for exchange and production of planting material. Virus elimination methods (heat treatment, cryotherapy and chemotherapy) are being explored to establish a reliable protocol for yam virus cleaning.

GRC plays also a major role in training and capacity building of national programs with respect to collection, conservation and characterization of genetic resources of yam.

For further information visit: http://www.iita.org/genetic-resources.