Optimization of high frequency plant regeneration protocol via embryogenic callus formation from diverse indica rice genotypes induced by combinations of 2,4-D and BA

Abstract

A high frequency plant regeneration protocol via induction of embryogenic callus followed by somatic embryogenesis was standardized for a group of indica rice varieties consisting of land races and improved varieties, which are generally considered recalcitrant. Scutellum derived embryogenic calluses were obtained from the mature seeds inoculated into MS medium supplemented with different concentrations and combinations of 2,4-D and BA added with casein hydrolysate (500 mg/l) and proline (1 g/l). The varieties significantly differed in their response to embryogenic callusing and regeneration. Maximum embryogenic callus formation was induced in all the varieties by altering the combinations and concentrations of 2,4-D(1.0-2.0 mg/l) and BA (0.01, 0.1 and 0.5 mg/l). The land races viz., Karnel, SavuluSamba and Doddabyranellu showed higher embryogenic callus formation in all the combinations and concentrations of 2,4-D and BA. But the improved varieties showed embryogenic callus induction only in particular concentration and combinations of growth regulators. However, an increasing trend of plant regeneration was observed in regeneration media consisted of MS salts supplemented with 3.0 mg/ l BA and 1.0 mg/l NAA. We showed that maximum plant regeneration through generation of embryogenic calluses induction in indica rice varieties can be induced by altering the concentrations and combinations of 2,4-D and BA.