Mechanisms of salinity tolerance and their possible application in the breeding of vegetables

Mostafakamal Shams, Ali Khadivi

In dry and semi-arid areas, salinity is the most serious hazard to agriculture, which can affect plant growth and development adversely. Over-accumulation of Na+ in plant organs can cause an osmotic effect and an imbalance in nutrient uptake. However, its harmful impact can vary depending on genotype, period of exposure to stress, plant development stage, and concentration and content of salt. To overcome the unfavorable effect of salinity, plants have developed two kinds of tolerance strategies based on either minimizing the entrance of salts by the roots or administering their concentration and diffusion. Having sufficient knowledge of Na+ accumulation mechanisms and an understanding of the function of genes involved in transport activity will present a new option to enhance the salinity tolerance of vegetables related to food security in arid regions. Considerable improvements in tolerance mechanisms can be employed for breeding vegetables with boosted yield performance under salt stress. A conventional breeding method demands exhaustive research work in crops, while new techniques of molecular breeding, such as cutting-edge molecular tools and CRISPR technology are now available in economically important vegetables and give a fair chance for the development of genetically modified organisms. Therefore, this review highlights the molecular mechanisms of salinity tolerance, various molecular methods of breeding, and many sources of genetic variation for inducing tolerance to salinity stress.