CRYOPRESERVATION OF EMBRYOGENIC CALLUSES OF 2 COMMERCIAL CLONES OF HEVEA-BRASILIENSIS

two cryopreservation protocols, one using a classical freezing process and the other a simplified freezing process, were developed for embry ogenic calluses of a commercial clone of Hevea. After preculture with 1M sucrose and 10% DMSO, embryogenic calluses were frozen in a program mable freezer at 0.2 degrees C . min(-1) down to -40 degrees C, or in a simple device consisting of an isopropanol bath enclosed in a polyst yrene box, placed in a -80 degrees C deep-freezer, thus achieving an a verage cooling rate of 0.2 degrees C . min(-1) down to -40 degrees C. High survival and rapid regrowth, as well as production of somatic emb ryos, were obtained with calluses cryopreserved using both freezing pr otocols. The simple freezing protocol was successfully used with a sec ond commercial clone.