A SIMPLIFIED PROTOCOL FOR CRYOPRESERVATION OF EMBRYOGENIC TISSUE OF SWEET-POTATO (IPOMOEA-BATATAS (L) LAM) UTILIZING SUCROSE PRECULTURE ONLY

Embryogenic tissue of six sweet potato (Ipomoea batatas (L) LAM) genot ypes of differing geographic origin was maintained on Murashige and Sk oog (1962) medium (MS) supplemented with 5 mu M 2,4-dichlorophenoxyace tic acid. Embryogenic aggregates (9 - 12 mg fresh mass) were precultur ed on MS medium supplemented with up to 0.7M sucrose prior to rapid fr eezing in liquid nitrogen. Survival of embryogenic tissue of all the g enotypes was obtained, with four of these ranging from 37% to 87%. Min or adjustments in the sucrose levels before and after freezing had dif fering effects on the survival of embryogenic tissue of different geno types. Embryogenic tissue recovered after cryopreservation appeared to develop normally.