Genetic variation in drought stress tolerant rice variety NSIC Rc9 (Apo) through In Vitro mutagenesis

Abstract

In vitro mutagenesis, a technique combining tissue culture and irradiation, of the drought-tolerant rice variety National Seed Industry Council (NSIC) Rc9 (Apo), resulted in the generation of an induced mutant population. Irradiation of gamma rays at four doses (10 Gy, 30 Gy, 50 Gy, and 70 Gy) was applied to callus pieces derived from tissue-cultured mature seeds. The control (0 Gy) determined the effect of irradiation doses on tissue culture response in callus induction and regeneration. A decreasing trend in callus induction and regeneration efficiency was observed with the increasing dosage of gamma ray. Increasing the gamma ray irradiation doses also increased the incidence of necrosis. The irradiated calli regenerated green plantlets, which produced the IVM2 mutant population. The variability evaluation showed a wide variation in agro-morphological traits, viz., pigmentation in basal leaf sheath, leaf blade, ligule, and collar, angles of leaf blade, culm and flag leaf, panicle exsertion, axis, type and secondary branching, grain size and shape, flowering days, plant height at maturity, panicle length and productive tiller number of the mutant population derived from the combination of tissue culture and gamma irradiation, compared to the variability induced using tissue culture alone identifying 30 Gy and 50 Gy with the most induced variability. The cluster analysis supported the variation of the mutants from the wild type, NSIC Rc9, in terms of phenotypic characteristics. The results showed the efficiency of in vitro mutagenesis in inducing a larger spectrum of mutation compared to using tissue culture and gamma irradiation singly.