Integrated approaches for increasing plant yield under salt stress

Abstract

Salt stress affects large cultivated areas worldwide, thus causing remarkable reductions in plant growth and yield. To reduce the negative effects of salt stress on plant growth and yield, plant hormones, nutrient absorption, and utilization, as well as developing salt-tolerant varieties and enhancing their morpho-physiological activities, are some integrative approaches to coping with the increasing incidence of salt stress. Numerous studies have been conducted to investigate the critical impacts of these integrative approaches on plant growth and yield. However, a comprehensive review of these integrative approaches, that regulate plant growth and yield under salt stress, is still in its early stages. The review focused on the major issues of nutrient absorption and utilization by plants, as well as the development of salt tolerance varieties under salt stress. In addition, we explained the effects of these integrative approaches on the crop's growth and yield, illustrated the roles that phytohormones play in improving morpho-physiological activities, and identified some relevant genes involve in these integrative approaches when the plant is subjected to salt stress. The current review demonstrated that HA with K enhance plant morpho-physiological activities and soil properties. In addition, NRT and NPF genes family enhance nutrients uptake, NHX1, SOS1, TaNHX, AtNHX1, KDML, RD6, and SKC1, maintain ion homeostasis and membrane integrity to cope with the adverse effects of salt stress, and sd1/Rht1, AtNHX1, BnaMAX1s, ipal-1D, and sft improve the plant growth and yield in different plants. The primary purpose of this investigation is to provide a comprehensive review of the performance of various strategies under salt stress, which might assist in further interpreting the mechanisms that plants use to regulate plant growth and yield under salt stress.

Keywords: CRSIPER-Cas9; genes; morpho-physiological and biochemical activity; nutrient uptake; salt stress; yield.

Figure 1

Integrated approach mitigate the negative effects of salt stress and improve plant growth and yield.

Figure 2

Nutrients mitigate the adverse effects of salt stress. Plant cells accumulate salt-effected ions such as Na⁺ and Cl^- that reduce N, P, and K uptake and photosynthetic activity. Plants organelles such as mitochondria, chloroplast, and peroxisome are exposed to higher salt stress, including the hydroxyl radical (OH), superoxide (O2^-), and hydrogen peroxide (H₂O₂), produce more reactive oxygen species (ROS), which negatively affect protein, lipids nucleic acid, and cellular damage. For self-defense, plants produce different antioxidant enzymes, such as CAT, POD, and SOD, to eliminate the negative effects of salt stress. Macronutrients N, P and K play a major role in enzyme activation photosynthesis, protein content, stomatal opening and closing, energy transmission, and osmoregulation under salt stress. K play a vital role in osmotic regulation compared to N and P. The combined application of K with humic acid counters the negative effects of ROS and improves the morph-physiological activity and yield of various crops.

Figure 3

Different genes are involved in plant nutrient uptake and enhanced plant growth and yield under salt stress. Two gene families, NRT and NPF, enhance the uptake of NO3^- via two transportation methods: low-affinity transport systems (LATS) and high-affinity transport systems (HATS). RNT genes are especially involved in HATS, while NPF is involved in LATS. Some genes, such as NPF6.3 and NRT1.1/CHL1, are involved in the dual-transport system. The genes NPF6.3 transport a variety of substrates such as protein, dipeptides, chloride, glucosinolates, gibberellins (GAs), jasmonate (JAs), indole-3-acetic acid (IAA), abscisic acid (ABA) to the various parts of the plants.

Figure 4

The selection of suitable cultivars can mitigate the negative effects of salt stress. For higher yield, it’s important to know the morph-physiological activity of the cultivars. The phyto-hormones such as gibberellins (GAs), ascorbate (ASA), and salicylic acid (SA) can mitigate the adverse effects of salt stress via two application methods such as foliar and seed priming. The application of GAs improves germinations, roots, shoot, oxygen absorption, and nutrient uptake in sorghum, mung bean, and eggplant, ASA improves germinations, roots, shoot, oxygen absorption, nutrient uptake in sorghum, mung bean, and eggplant, and SA improves morpho-physiology activities, and oxidative damage in cotton and mung bean. The genes such as GA2ox, GA2ox5, GA2ox6, GA2ox, GA2ox7, XERICO and GASAA are involved in endogenous phyto-hormones and increase plant yield.