CBN-V Video Archives - S7-08
Preliminary Studies on the Cryopreservation of Meristems and Seeds of Wild Manihot Species

Escobar R.H.¹, N.C. Manrique², F. Gil¹, J. Tohme² and D.G. Debouck¹

1. Genetic Resources Unit Centro Internacional de Agricultura Tropical (CIAT) Apartado Aéreo 6713, Cali, Colombia R.ESCOBAR@CGIAR.ORG
2. Biotechnology Research Unit, CIAT, Apartado Aéreo 6713, Cali, Colombia

        Wild Manihot species are maintained at CIAT as a field gene bank and as a small in vitro collection. Under field conditions, these species are exposed to pests and diseases, and their flowering and seed set are variously affected by environmental conditions. Twenty-nine species and 300 genotypes are maintained in vitro with subculturing every 6-12 months. Both conservation options are seen as temporary given their costs and space and manpower requirements. Two additional approaches for the long-term conservation of Manihot diversity are being tested: cryopreservation of meristematic tissues (conservation of individual genotypes) and storage of botanical seeds (conservation of population genetic diversity). Modifications of the encapsulation-dehydration protocol already successfully used for shoot tips of cassava (M. esculenta) were tested on two genotypes of M. carthaginensis, three genotypes of both M. esculenta subsp. peruviana and subsp. flabellifolia. Preliminary results showed that plants could be recovered after freezing with a 0-60% survival. Seeds in cold storage have been kept up to seven years without loss of viability; if maintained at room temperature however, they lose viability after one year. A protocol developed in 1990 to cryopreserve seeds and zygotic embryos has been modified by warming the plant material after freezing. Experiments have been undertaken with seeds of three Manihot species by freezing them in liquid nitrogen for 60 days. Recovery of seeds will be scored after two months.

For further information, see spoken presentation Escobar et al. S7-07