Molecular Evolution of Plant SULTR Proteins and Expression Analysis of HvSULTR Under Heat Stress in Barley

Sulfur metabolism plays an important role in plant growth and environmental adaptation. Sulfate transporters (SULTRs) are essential players that mediate sulfur acquisition and distribution in many plants, thereby influencing the cellular redox homeostasis under abiotic stress. In this study, we identified 16 putative HvSULTRs genes in barley at the genome-wide level. The conservation and divergence of the SULTR gene family were assessed through a phylogenetic tree and gene structure analysis, revealing that these genes are closely distributed along the chromosomes. Furthermore, the expression pattern of SULTRs in multiple tissues, including flower, root, leaf, stem, seeds, female, male, root meristem, and apical meristem, were analyzed among ten land plants using a public database. Interestingly, the expression of HvSULTR2, HvSULTR4, and HvSULTR5 was upregulated after four days of heat treatment, suggesting their importance in barley's adaptive response to heat stress. In addition, HvSULTR11 was confirmed to be localized at the plasma membrane and display functional interactions with Hv14-3-3A/Hv14-3-3D. In addition, haplotypes of the HvSULTR11 based on SNP (Single Nucleotide Polymorphism) were divided into ten types across 123 barley varieties. Together, these results provide a new clue to clarify the molecular mechanism of SULTRs in stress response and a new candidate gene resource to enhance the stress (e.g., heat and drought) tolerance in barley.