In vitro Regeneration and GUS Gene Transformation in Rice (Oryza sativa L.)

Abstract

Rice is the most important cereal crop in Bangladesh and it was the first attempt in Bangladesh to transform rice plant with target genes. As a new intervention deserves enormous efforts to develop the optimum conditions in order to accomplish effective transformation. Scutellum, leaf base, mesocotyl and root explants of six rice genotypes viz. BR-22, BR-23, BRR.I dhan-29, BRR.I dhan-30, BRR.I dhan-28 and BRRI dhan-31 were cultured in N6, LS and MS basal media containing different concentrations and combinations of 2,4-D to induce callus. 2,4-D plays an important role in callus induction of plant tissue and 2.0 mg/12,4-D was the most suitable for callus induction in rice. A wide range of variation in callus induction was marked in this experiment with respect to their explants and treated media. Three varieties BRR.I dhan-30, BRR.I dhan-28 and BRR.I dhan-31 proved more competent ones to induce callus with all of their four explants. On the contrary, the varieties BR-22, BR-23 and BRR.I dhan-29 failed to induce callus in all their explants tissue. In respect of explants, the scutellum proved more efficient and gave highest callus formation (77%) followed by root (61 %). In respect of nutritional strength, N6 media gave highest percentage of callus formation followed by LS medium. In respect of genotypic performance, BRRI dhan-30 was found as the most efficient variety producing 68% callus induction followed by BRR.I dhan-28 (62%). Calli derived from individual explant were subjected to regeneration media and their comparative performances were evaluated. In the comparative study BRR.I dhan-30 proved to be the best variety giving 88% regeneration frequency from somatic embryogenesis. Three explants; scutellum, leaf base and mesocotyl were used as the target tissue explants and scutellum derived Calli gave highest regeneration (88%) followed by mesocotyl (32%). The embryogenic Calli were treated to three regeneration media supplemented with different phytohormones and MS medium containing sorbitol (3%) was found to be the best medium for regeneration in tested rice varieties. In meristem culture the highest regeneration frequency was observed in excised meristem isolated from four days old seedlings. Variable range of regeneration response was observed in different rice varieties. The varieties BRRI dhan-28 and BRRI dhan-30 gave the highest percentage of regeneration 65% and 56% respectively from meristem culture. Considering the overall performance covering both the purviews of callus induction and regeneration BR.RI dhan-30 was selected as the target variety for transformation studies because of its best in vitro tissue culture response and economic imp011ance in the country………………………….