Use of Biotechnology to Improve Tolerance in Rice to Drought Stress

The mutation approach combined with tissue culture can be useful tool to study drought tolerance mechanisms under in vitro conditions to enhance of rice breeding program. This study was conducted to determine the effect of gamma radiation on enhancing drought tolerant rice varieties MRQ74 and MR269 through the in vitro technique. Different doses of acute gamma rays (100¿700 Gy) were applied to investigate the effects of radiation on seeds. Based on germination rate and plant height, the lethal dose (LD50) was found to be 350 Gy. Plantlets were produced by using two methods (indirect and direct). The first involved indirect in vitro plant regeneration through naked seeds being exposed to acute gamma irradiation (350 Gy) for mutation induction, and then cultured on to MS medium supplemented with different concentrations of 2, 4-D, and Kin for four weeks to produce callus. Drought stress was applied to callus under different concentrations (1.5%, 3%, 4.5%, 6%, and 7%) of Polyethylene glycol PEG (MW 6000) and the effects on the best induction of callus, fresh weight, and proline concentrations were investigated. Healthy callus were selected at highest concentrations of PEG to shoot and