Salt stress resilience in plants mediated through osmolyte accumulation and its crosstalk mechanism with phytohormones

Abstract

Salinity stress is one of the significant abiotic stresses that influence critical metabolic processes in the plant. Salinity stress limits plant growth and development by adversely affecting various physiological and biochemical processes. Enhanced generation of reactive oxygen species (ROS) induced via salinity stress subsequently alters macromolecules such as lipids, proteins, and nucleic acids, and thus constrains crop productivity. Due to which, a decreasing trend in cultivable land and a rising world population raises a question of global food security. In response to salt stress signals, plants adapt defensive mechanisms by orchestrating the synthesis, signaling, and regulation of various osmolytes and phytohormones. Under salinity stress, osmolytes have been investigated to stabilize the osmotic differences between the surrounding of cells and cytosol. They also help in the regulation of protein folding to facilitate protein functioning and stress signaling. Phytohormones play critical roles in eliciting a salinity stress adaptation response in plants. These responses enable the plants to acclimatize to adverse soil conditions. Phytohormones and osmolytes are helpful in minimizing salinity stress-related detrimental effects on plants. These phytohormones modulate the level of osmolytes through alteration in the gene expression pattern of key biosynthetic enzymes and antioxidative enzymes along with their role as signaling molecules. Thus, it becomes vital to understand the roles of these phytohormones on osmolyte accumulation and regulation to conclude the adaptive roles played by plants to avoid salinity stress.

Glycine Betaine

“…Salinity stress negatively impacts the overall biological functions of plants (Figure 2); however, the severity depends on the concentration and duration of exposure, plant species, and growth stages [61]. Salinity stress enhanced ROS generation, damaging the cell membranes, proteins, and nucleic acids and ultimately hampered growth, biomass productivity, and yield [62,63,64,65]. Soil microbial biomass and various enzymatic activities are also affected under salinity stress which deteriorates the soil quality, fertility, and overall crop production [66,67].…”

Does Potassium Modify the Response of Zinnia (Zinnia elegans Jacq.) to Long-Term Salinity?

“…The second phase takes place over days or even weeks and is caused by excessive toxic ions in plant cells, which harm metabolic processes [ 24 ]. The response to salinity is complex and involves numerous adjustments at morphological (early flowering, growth inhibition, prevention of lateral shoot development, root adaptations), physiological (stomatal closure, osmotic adjustment, Na/K discrimination), and biochemical levels (antioxidant activity, change in hormone level, increased proline level), which help plants cope with stress [ 23 , 24 , 25 ].…”

“…Proline accumulation is another example of the salt stress coping strategy [ 25 , 29 ]. This amino acid may be involved in stress avoidance and stress tolerance strategies.…”

“…Besides acting as an osmolyte, proline is a membrane and protein stabilizer, as well as a free radical scavenger. It protects plant cells against the detrimental effects of dehydration and the accumulation of toxic ions [ 25 , 30 ]. The proline level in plant cells is controlled by several cellular mechanisms responsible for its synthesis and degradation [ 25 , 29 ].…”

Plant Growth Stimulators Improve Two Wheat Cultivars Salt-Tolerance: Insights into Their Physiological and Nutritional Responses

“…The absorption of high concentrations of Na + in cells limits K + uptake, resulting in Na + toxicity and nutrient imbalance during salt stress [ 1 ]. In order to establish the defense, plants restrict the accumulation of salt ions in the cytosol and enhance the synthesize of osmolytes [ 3 , 4 , 5 ]. Osmolyte biosynthesis is critical for maintaining osmotic potential, metabolic activity, and water uptake under saline conditions [ 6 ].…”