CRYOPRESERVATION OF SOMATIC EMBRYOS - A TOOL FOR GERMPLASM STORAGE AND COMMERCIAL DELIVERY OF SELECTED PLANTS

The development of long-term preservation methods of somatic embryos w as investigated as a contribution to synthetic seed technology. Thus, cryopreservation in liquid nitrogen was attempted with somatic embryos of two species, Coffea canephora Pierre and Daucus carota L. Cryopres ervation of carrot embryos simply required a 21-h sucrose pretreatment followed by a prefreezing step at -20 degrees C. A freeze-hardening t reatment consisting of embryo culture in the presence of high sucrose molarity and 1 mu M ABA was developed for coffee embryos. Following de siccation at 75% relative humidity (RH) and + 24 degrees C for 7 d, em bryos were frozen by rapid immersion in liquid nitrogen. Direct regrow th of frozen-thawed embryos was obtained for the majority of both carr ot and coffee embryos. Even large carrot embryos were able to survive cryopreservation. The size of embryos and the age of the embryogenic s train from which the embryos originated determined their ability to de velop into normal plantlets. Direct regrowth without any secondary cal logenesis and/or embryogenesis is a prerequisite for practical use of preserved embryos either in a nursery or through direct planting.