Mechanisms and Signaling Pathways of Salt Tolerance in Crops: Understanding from the Transgenic Plants

Soil salinization is a serious agricultural issue that is severely affecting crop production across the world. Salt induced stresses are mainly included osmotic and ionic stresses, which could lead to other stresses e.g., oxidative stress in plants. The evolved plant mechanisms in salt tolerance are categorized into osmotic tolerance and ionic homeostasis mediated by ion exclusion and ions sequestration into vacuole. Osmotic tolerance involves long-distance signaling which still has many unknowns in crops, while ionic homeostasis is achieved by Na+/K+/H(+)transporters and H+-pumps. Besides, the mechanisms of salt tolerance are regulated by various signaling pathways and transcription factors. A better understanding on the mechanisms of salt tolerance and its involved candidate genes is a prerequisite for increasing/maintaining yield potential of crops in saline soils. This review focuses on various mechanisms, signaling pathways and transcriptional regulations of salt tolerance in crops. We also review the various examples of underlying candidate genes that have been engineered to develop the salt tolerant crops, and may also have worth in next crop breeding.