Use of gamma radiation to induce mutations in rice (Oryza sativa L.) and the selection of lines with tolerance to salinity and drought

One of the strategies for genetic improvement of Oryza sativa L. (rice) is the use of radiation-induced mutagenesis to search for materials suitable for production in marginal conditions, such as drought and salinity. In this present study, indica rice ‘CR-5272’ embryogenic calluses and seeds were exposed to gamma radiation. Survival and growth of plants derived from embryogenic calluses and seeds were evaluated in vitro in the presence of selection factors for salinity and drought (NaCl and sorbitol). Plants regenerated from irradiated calluses and seeds were screened for tolerance to these conditions and promising lines were identified. Culture of plants regenerated from irradiated calluses (M1) allowed the selection of 60, 58 and 15 promising lines with tolerance to salinity, drought, and both factors, respectively. Six promising salt-tolerant lines and four drought-tolerant lines were selected from plants grown from irradiated seeds (M2). A hormetic response to irradiation was observed in seeds; seeds irradiated at 50 Gy showed increased callus induction and callus weight. This study allowed advancements in the improvement of rice ‘CR-5272’ through the production of promising lines that are being evaluated in field studies.