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 (<i>SULTRs</i>) 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 <i>HvSULTRs</i> genes in barley at the genome-wide level. The conservation and divergence of the <i>SULTR</i> 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 <i>SULTRs</i> 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 <i>HvSULTR2, HvSULTR4</i>, and <i>HvSULTR5</i> was upregulated after four days of heat treatment, suggesting their importance in barley's adaptive response to heat stress. In addition, <i>HvSULTR11</i> 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 <i>HvSULTR11</i> 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 <i>SULTRs</i> in stress response and a new candidate gene resource to enhance the stress (e.g., heat and drought) tolerance in barley.