Optimization of Callus Induction and Regeneration in Swarna Masoori Rice Cultivar Short Title: in Vitro Somatic Embryogenesis of Swarna Masoori Rice Cultivar

Callus induction was optimized in Swarna masoori rice cultivar, a local variety of Andrapradesh, India, during somatic embryogenesis, using various concentration of 2, 4-D. The seeds were inoculated in Murashige and Skoog medium with various concentrations of 2, 4-D (2mg/L, 4mg/L, 8mg/L and 16mg/L) and the growth of the callus was observed from 2nd to 7th week. The focus of the study was to optimize the concentration of 2, 4-D to induce efficient callus for subsequent transformation experiments. From the results it was seen clearly that 2 to 4 mg/L of 2, 4-D induced substantial callus growth than 8 to 16 mg/L which caused callus browning after 3rd week. Although 2 to 4 mg/L of 2, 4-D induced efficient callus, callus induction by 2 mg/L was found to be efficient to regenerate into shoots and roots were as most of the callus induced by 4mg/L of 2, 4-D regenerated into roots. Therefore, we conclude that 2 mg/L of 2, 4-D was found to be efficient to induce callus in swarna masoori rice cultivar. The callus obtained from 2, 4-D (2mg/L) induction can be transformed with genes of agronomically important traits, which have the potential to regenerate into an entire plant.