CRYOPRESERVATION OF CELL-SUSPENSIONS AND EMBRYOGENIC CALLUSES OF CITRUS USING A SIMPLIFIED FREEZING PROCESS

A simplified cryopreservation process was experimented with a cell sus pension of willow leaf mandarin and embryogenic calluses of six variet ies of-Citrus. Its efficiency was comparable to that of the standard f reezing protocol developed-previously for these materials, which requi red the use of a programmable freezing apparatus. The cell suspension could be frozen without modifying the original pretreatment conditions (0.15 M sucrose + 5 % DMSO). Embryogenic calluses of five varieties o ut of the six experimented withstood cryopreservation with the simplif ied freezing process. Optimal results were obtained by increasing the DMSO concentration to 10 or 15 %.