A Review on Understanding the Effects and Mechanisms of Salinity Tolerance in Rice (Oryza sativa L.)

Abstract

Salinity, along with drought, is one of the key abiotic stressors that has posed a danger to the advancement and evolution of cereal crops like rice and wheat. Water shortage and a lack of irrigation water availability are the main causes of salty soil formation. Rice is salt sensitive and glycophyte, wheat is moderately salt tolerant. Wild tolerant cultivars like Oryza coarctata and Oryza alta are more tolerant than traditional cultivars such as Pokkali and Nona Bokra in rice. Salt stress affects crop plants’ processes like ionic imbalance, osmotic and oxidative stress. Na+ should be low in the shoots of the plant which is restricted by various transporters in the cell membrane of the roots in soil. High K+ & Na+/K+ homeostasis should be maintained. Many RILs and NILs have been developed which acts as a donor for salinity tolerant genes. FL478 is a recombinant inbred line in which candidate genes are situated in the Saltol region of chromosome 1 region which is obtained by a cross between Pokkali x IR29. Increase in world’s population, rice output must be increased by at least 25% by 2030 and 50% by 2050.Salinity stress is a polygenic character which involves several genes works in harmony. For evolution of salinity tolerant cultivars, we need to access the physiological, biochemical genetic responses of the crop plant which helps in transfer of candidate genes from donor parents to elite high yielding salt sensitive cultivars. Especially in rice salt tolerant mechanisms like, Ion equilibrium regulation, Adjustment of osmotic potential, Reduction of ROS, Nutrient disequilibrium, and Regulation of PGRs. Conventional, MABC, MAS and direct gene transfer by transgenic methods. This review paper's main objective is to understand the mechanisms of the crop plants to salinity effects and development of salt tolerant cultivars by modern approaches which fulfill the food scarcity of staple food crops with increasing population.