CBN-V Video Archives - S8-06
CIAT Cassava in vitro Collection Cleaned against Seedborne Diseases of Quarantine Importance

Flor N.C., B. Pineda and G. Mafla

Genetic Resources Unit, Centro Internacional de Agricultura Tropical, (CIAT),Apartado Aéreo 6713, Cali, Colombia g.mafla@cgiar.org

        Availability of germplasm is a basic requisite for the improvement of cassava (Manihot esculenta Crantz) across the tropics. In order to ensure that availability, the Genetic Resources Unit at CIAT undertook in 1996 a screening of the entire in vitro collection for the presence/absence of seedborne diseases of quarantine importance. The in vitro collection currently has 6210 clones, of which 5728 have been designated to the Food and Agriculture of the United Nations. By using the in vitro technology, namely micropropagation, cassava germplasm is generally free of insects, fungi, and bacteria. In order to make sure the germplasm is free of viruses and viroids, the material has been passed through thermotherapy (initially on cassava stakes at 40 oC, and if positive, on in vitro plantlets after excision of meristems). Two diagnosis techniques have been used: ELISA for Cassava common mosaic virus and Cassava symptomless X virus, and grafting of a hypersensitive clone for the causal agent of the Frog Skin Disease Agent (FSDA). Three improvements of the grafting have been done in order to fasten the indexing. By July 2001, 79% of the clones have been certified against CCMV, 76% against CsXV and 52% against FSDA. Cleaning and indexing of the entire collection should be completed by December 2001.

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