Differential Responses to Salt Stress in Four White Clover Genotypes Associated With Root Growth, Endogenous Polyamines Metabolism, and Sodium/Potassium Accumulation and Transport

Abstract

Selection and utilization of salt-tolerant crops are essential strategies for mitigating salinity damage to crop productivity with increasing soil salinization worldwide. This study was conducted to identify salt-tolerant white clover (Trifolium repens) genotypes among 37 materials based on a comprehensive evaluation of five physiological parameters, namely, chlorophyll (Chl) content, photochemical efficiency of PS II (Fv/Fm), performance index on an absorption basis (PIABS), and leaf relative water content (RWC), and to further analyze the potential mechanism of salt tolerance associated with changes in growth, photosynthetic performance, endogenous polyamine metabolism, and Na+/K+ uptake and transport. The results showed that significant variations in salt tolerance were identified among 37 genotypes, as PI237292 and Tr005 were the top two genotypes with the highest salt tolerance, and PI251432 and Korla were the most salt-sensitive genotypes compared to other materials. The salt-tolerant PI237292 and Tr005 not only maintained significantly lower EL but also showed significantly better photosynthetic performance, higher leaf RWC, underground dry weight, and the root to shoot ratio than the salt-sensitive PI251432 and Korla under salt stress. Increases in endogenous PAs, putrescine (Put), and spermidine (Spd) contents could be key adaptive responses to salt stress in the PI237292 and the Tr005 through upregulating genes encoding Put and Spd biosynthesis (NCA, ADC, SAMDC, and SPDS2). For Na+ and K+ accumulation and transport, higher salt tolerance of the PI237292 could be associated with the maintenance of Na+ and Ca+ homeostasis associated with upregulations of NCLX and BTB/POZ. The K+ homeostasis-related genes (KEA2, HAK25, SKOR, POT2/8/11, TPK3/5, and AKT1/5) are differentially expressed among four genotypes under salt stress. However, the K+ level and K+/Na+ ratio were not completely consistent with the salt tolerance of the four genotypes. The regulatory function of these differentially expressed genes (DEGs) on salt tolerance in the white clover and other leguminous plants needs to be investigated further. The current findings also provide basic genotypes for molecular-based breeding for salt tolerance in white clover species.

Nitric oxide signal is required for glutathione-induced enhancement of photosynthesis in salt-stressed Solanum lycopersicum L

“…PI abs is a comprehensive index that reflects photochemical efficiency. Previous studies have indicated that the reduction in PI abs is more sensitive than F v /F m , accurately indicating the impairment of the plant’s photosynthetic machinery and the decrease in photochemical efficiency under adverse condition ( Chen et al., 2021 ; Li et al., 2022b ). The decrease in P n due to NaCl stress was influenced by both stomatal-limiting and non-stomatal-limiting factors.…”

Molecular Mechanism of Exogenous Magnesium in Regulating Cation Homeostasis in Roots of Peanut Seedlings under Salt Stress

“…Exogenous magnesium can also maintain K + homeostasis in cells. Some studies suggest that the gene expression of POT/HAK family members may be directly regulated by the cytosolic Ca 2+ level under salt stress [56]. SKORs participate in the absorption and transportation of potassium from roots, which may regulate the salt tolerance of plants [57].…”

A bermudagrass variant exhibits strong tolerance to low temperature associated with enhanced sugar metabolism and cold‐responsive pathways

“…In addition, high EL level and overaccumulation of MDA are two main indicators of cold injure in plants, as EL or MDA indicates cell membrane stability or membrane lipid peroxidation, respectively (Blum & Ebercon, 1981; Dhindsa et al., 1981). Previous studies have used Chl, Fv/Fm, PI ABS , EL, or MDA to evaluate and identify genotypic variation in tolerance to various abiotic stresses such as low temperature, high temperature, and salt stress (Li et al., 2022a, 2021; Zhang et al., 2011). A recent study demonstrated that bermudagrass experienced quick declines in Chl content, Fv/Fm, and PI ABS under chilling stress (Zhou et al., 2022).…”