Résumé
Cryopreservation using encapsulation-dehydration of apices of in vitro plantlets was investigated with sugarcane (Saccharum sp.), cassava (Manihot esculenta) and two coffee species (Coffea racemosa and C. sessiliflora). Maximum survival rates of frozen apices were 91% with sugarcane, 60% with cassava and 38% with coffee. Growth recovery of cryopreserved sugarcane apices was rapid and direct. With cassava and coffee, callusing was often observed during recovery of frozen apices, thus reducing the number of plants regenerated. Restriction fragment length polymorphism analyses of sugarcane revealed several modifications in the band patterns of plants regenerated both from control and cryopreserved apices which were identical in both materials. These variations were therefore not due to freezing but preexisting among the in vitro plantlets used. These results demonstrate that the encapsulation-dehydration technique can be employed for cryopreservation of apices of some tropical species.