Regeneration of plants from long-term cultures of Oryza sativa L.

Root and embryo derived callus tissues of rice grown on sucrose alone as carbon source lost their ability to organise shoots by 75 and 100 days in culture respectively. Along with 2% sucrose, either 3% sorbitol or 3% mannitol was found to be necessary in the growth medium for the callus to regenerate whole plants over a period of 1400 days without any decline in the shoot forming ability. Our results indicated that incorporation of sorbitol or mannitol in the callus proliferating medium provides long-term totipotent rice cultures with a high frequency (50-60%) of shoot differentiation.