Investigation of Salinity Tolerance Related Gene Expression in Rice (Oryza sativa L.)

Rice ranks second with the highest consumption rate after corn in world production. As a result of various biotic and abiotic stress factors exposed during production, plants quit normal growth. Under such conditions, plants have developed survival mechanisms at the molecular level in order to maintain their existence. Phenotypic data is widely used to evaluate plant tolerance with assistance of gene expression analysis that interprets the source of tolerance. In this study, Osmancık-97 rice variety which is extensively cultivated in Türkiye was grown under four different salt (NaCl) concentrations (60, 90, 120 mM and control) in in vivo conditions. The study aimed to determine the expression differences of the TPS1, NHX1, SOS1 and HKT2;1 genes under increasing salinity conditions. In the highest applied NaCl concentration (120 mM), TPS1, NHX1, SOS1 and HKT2;1 gene expression decreased 78.2, 74.0, 78.3, and 73.5% compared to the control, respectively. In the same concentration, parameters of photosynthetic pigment content, average plant length, fresh and dry weight, and root length decreased significantly. In contrast, proline accumulation and TBARS content presented significant increases. The difference in ion homeostasis and salt tolerance among species or varieties is related to the expression of regulatory genes. Rice, a moderately salt sensitive crop, has complex responses to salt stress and its sensitivity varies according to species, variety, growth and development stages and the duration of stress to which it is exposed.