Stimulatory effect of partial desiccation on plant regeneration in indica rice (Oryza sativa L)

A simple in vitro protocol was established for high frequency plant regeneration via organogenesis and somatic embryogenesis from the callus cultures derived from immature inflorescence segments of indica rice (Oryza sativa L cvs Safari-17 and Kasturi). Embryogenic and nodular calli were initiated on MSB medium supplemented with 2, 4-D and sucrose (3.0%, w/v), Somatic embryogenesis occurred after transfer of embryogenic calli to MSB medium containing 2.25 muM 2,4-D, 2.2 muM BAP, 2.9 muM thiamine HCl and 244.86 muM L-tryptophan. Plantlet/shoot regeneration occurred after transfer of embryogenic calli to MSB medium containing 17.6 muM BAP and 1.12 muM 2,4-D, Partial desiccation (up to 12, 24, 48, 72 and 96 h) of embryogenic calli prior to transfer to regeneration medium stimulated regeneration frequency. Highly significant (P < 0.001) difference was observed for regeneration frequency and average number of plantlets/shoots regenerated per callus in partially desiccated calli in comparison to non-dehydrated calli, Regeneration frequency increased from 33.3% to 80% after 24 h of desiccation treatment to callus cultures of cv. Safari-17, and from 46.7% to 93.3% after 48 h of desiccation treatment to callus tissues of cv. Kasturi. Regenerated shoots were rooted on MSB medium supplemented with 4.9 <mu>M IBA. Plants with well-developed roots were transferred to pots where they grew well and attained maturity.