AUTHOR=Li Zhou , Geng Wan , Tan Meng , Ling Yao , Zhang Yan , Zhang Liquan , Peng Yan 

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

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 13 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.896436

DOI=10.3389/fpls.2022.896436

ISSN=1664-462X

ABSTRACT=Selection and utilization of salt-tolerant crops are essential strategies for alleviating salinity damage to crops productivity with increasing soil salinization worldwide. Current study were performed to identify salt-tolerant white clover (Trifolium repens) genotypes among 37 materials based on comprehensive evaluation of five physiological parameters including chlorophyll (Chl) content, photochemical efficiency of PS II (Fv/Fm), performance index on absorption basis (PIABS), and leaf relative water content (RWC), and to further analyze potential mechanism of salt tolerance associated with changes in growth, photosynthetic performance, endogenous polyamines metabolism, and Na+/K+ uptake and transport. Results showed that significant variation in salt tolerance were detected among 37 genotypes, as PI237292 and Tr005 were the top two genotypes with strongest salt tolerance, and PI251432 and Korla were most salt-sensitive genotypes than 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 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 up-regulating genes encoding Put and Spd biosynthesis (NCA, ADC, SAMDC, and SPDS2). For Na+ and K+ accumulation and transport, better salt tolerance of the PI237292 could be associated with 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) differentially expressed among four genotypes under salt stress. However, the K+ level and K+/Na+ ratio were not completely consistent with salt tolerance of four genotypes. Regulatory function of these differentially expressed genes (DEGs) on salt tolerance deserves to be further investigated in white clover and other leguminous plants. Current findings also provide basic genotypes for molecular-based breeding for salt tolerance in white clover species.