SOMATIC EMBRYOGENESIS IN ARACHIS-HYPOGAEA L - GENOTYPE COMPARISON

Somatic embryogenesis and embryogenic callus formation occurred from immature cotyledon and embryo axis explants of seven peanut (Arachis hypogaea L.) genotypes including one valencia, three Spanish and three Virginia botanical types. The initiation medium consisted of Murashige and Skoog's salts and vitamins with 3% sucrose and 0.5 mg/l picloram. There were significant differences among genotypes for somatic embryo formation, subculture capacity and plant regeneration using a single media sequence. Somatic embryo formation from cotyledons showed better correlation with plant regeneration than somatic embryo formation from the embryo axis. Maturity of the embryo explant, as estimated by cotyledon length, did not show a significant effect on response, but there was a trend toward reduced somatic embryo formation from older cotyledons. Relatively few plants were regenerated from the valencia genotype. All peanut genotypes tested thus far are competent for somatic embryogenesis and in vitro response could probably be improved by media manipulation.