Ion homeostasis for salinity tolerance in plants: a molecular approach

Abstract

Soil salinity is one of the major environmental stresses faced by the plants. Sodium chloride is the most important salt responsible for inducing salt stress by disrupting the osmotic potential. Due to various innate mechanisms, plants adapt to the sodic niche around them. Genes and transcription factors regulating ion transport and exclusion such as salt overly sensitive (SOS), Na+/H+ exchangers (NHXs), high sodium affinity transporter (HKT) and plasma membrane protein (PMP) are activated during salinity stress and help in alleviating cells of ion toxicity. For salt tolerance in plants signal transduction and gene expression is regulated via transcription factors such as NAM (no apical meristem), ATAF (Arabidopsis transcription activation factor), CUC (cup‐shaped cotyledon), Apetala 2/ethylene responsive factor (AP2/ERF), W‐box binding factor (WRKY) and basic leucine zipper domain (bZIP). Cross‐talk between all these transcription factors and genes aid in developing the tolerance mechanisms adopted by plants against salt stress. These genes and transcription factors regulate the movement of ions out of the cells by opening various membrane ion channels. Mutants or knockouts of all these genes are known to be less salt‐tolerant compared to wild‐types. Using novel molecular techniques such as analysis of genome, transcriptome, ionome and metabolome of a plant, can help in expanding the understanding of salt tolerance mechanism in plants. In this review, we discuss the genes responsible for imparting salt tolerance under salinity stress through transport dynamics of ion balance and need to integrate high‐throughput molecular biology techniques to delineate the issue.

Exogenous Myo-Inositol Alleviates Salt Stress by Enhancing Antioxidants and Membrane Stability via the Upregulation of Stress Responsive Genes in Chenopodium quinoa L.

“…Recently, Sun et al demonstrated that increased salinity tolerance in soybean over-expressing NHX gene reflected reduced oxidative damage and increased SOS1, SKOR, and HKT [58]. The regulated expression of NHX and SOS maintains the ratio of Na/K, thereby significantly affecting the growth under saline conditions [59,60]. Improving Na + exclusion leads to maintaining ion homeostasis in roots, thus ensuring relatively lower concentrations of toxic ions within shoot [61].…”

Genome-Wide Transcriptome Profiling, Characterization, and Functional Identification of NAC Transcription Factors in Sorghum under Salt Stress

“…Ionic and osmotic imbalances and oxidative damage are caused by high levels of salinity in roots, resulting in growth retardation, withering, or death [15]. Excess ROS can cause lipid peroxidation, protein oxidation, nucleotide damage, enzyme inhibition, and the activation of programmed cell death (PCD), which are all linked to signaling since the reaction products convey information to downstream processes [1,5,16]. To scavenge high ROS levels, an efficient system of enzymatic and non-enzymatic antioxidants is involved.…”

“…the WRKY, SNAC, MYB, and DREB families are regarded as the virtual switches that directly up-regulate or down-regulate the gene expression. Up-regulation of the NAC transcription factor was observed in salinity tolerance in rice and wheat cultivars [16]. In contrast to the ATPase activity, vacuolar pyrophosphatase (H + -PPase) activity pumps H + via the vacuolar membrane, providing another major driving force for sodium accumulation in the vacuole.…”

Molecular insights into the role of plant transporters in salt stress response

“…In order to survive, plants adapt the highly complex ion transport network along with other stress tolerance mechanisms that play important roles in the uptake of solutes from the soil (Tang et al, 2020a). In plant cells, diverse membrane proteins are involved in the regulation of cellular uptake and efflux of inorganic ions such as Na + , K + , Ca 2+ , Cl − , and other ions (Amin et al, 2020). In addition to their role in the maintenance of cellular ion homeostasis under normal and stress conditions, they are involved in nutrient transport, membrane potential, and signal transduction (Kumar & Mosa, 2015).…”