Genotype Dependent Somatic Embryogenesis and Regeneration from Leaf Base Cultures of Sorghum bicolor

A simple and reproducible protocol for callus induction and regeneration of plantlets from leaf base cultures of agronomically important Indian cultivars of Sorghum bicolor(L.) Moench (296 Band RS 585) has been developed. A strong genotype dependent response was observed and the genotype 296 B was found to be the most responsive as compared to the other genotypes tested. Cultures were raised from the III, IV and V leaf bases, excised from 12-day-old in vitro raised plantlets and cultured on Callus Induction Medium (CM). Callus initiation took place after 10-14 days of culture. The explants were maintained on this medium for 30- 35 days, after which they were transferred to Regeneration Medium (RM). Histological examination indicated that somatic embryogenesis was prevalent in the leaf base cultures and the embryos started to germinate after 15-20 days of transfer to RM. Plantlets with complete shoot and root system have been raised with as many as 30 plantlets regenerating from a single explant. These plantlets could be easily separated from one another and transferred to culture tubes for faster growth and development. Later, individual plants numbering more than 50 were transferred to pots containing soil: soilrite (1:1) for hardening. A high regeneration frequency of up to 40 % could be obtained in the genotype 296 B followed by 10.8 % in the genotype RS 585 and 7.8 % in C 43.