• Genome-wide identification, phylogenetic, and structural features of peach ST gene family were characterized. • Comparative transcriptome analysis revealed dynamic expression patterns of peach ST genes during fruit development. • By integration of GWAS, transcriptomic and functional analysis, a key candidate gene PpPMT1 was identified in regulating fruit sugar accumulation in peach. In plants, sugars serve not only as precursors and energy sources for various metabolic processes, but also function as essential signaling molecules modulating growth and development. The sugar transporter (ST) proteins play key roles in governing the transport of sugars from source to sink tissues. Although genes belonging to this family have been characterized in many plant species, studies on peach still remain limited. In this study, we systematically analyzed the peach ST gene family using an integrated approach combining bioinformatics, transcriptomics, genome-wide association study, and functional validation. A total of 65 ST genes were identified in the peach genome using homologs from tomato as queries. Phylogenetic analysis classified these STs into eight subfamilies, with their promoters harboring numerous cis-elements responsive to environmental and developmental signals and plant hormones. Transcriptome analysis revealed that 8 ST genes are persistently upregulated during peach fruit development, displaying distinct expression profiles. Furthermore, genome-wide association study (GWAS) on fruit soluble solid content (SSC) using 212 peach accessions identified a significantly associated SNP locus on chromosome 4. Based on transcriptomic expression patterns, the candidate gene Prupe.4G042700 was selected as key gene responsible for SSC and designated as PpPMT1 . Transient overexpression and silencing of PpPMT1 suggest its positive role in regulating sugar content in peach fruit. The clarified ST gene family and identified candidate gene will benefit our understanding of fruit sugar regulation in peach.
Li et al. (Sun,) studied this question.