The sugar transporter pbrstp10 promotes fructose and glucose accumulation in pear (Pyrus bretschneideri) fruit

Sugar transporter proteins (STPs) are integral to sugar transport and distribution in plants, regulating key physiological processes such as growth, development, and responses to biotic and abiotic stresses. Despite pear’s economic importance in the world, the roles of STP family members in pear fruit remain largely unexplored. Here, we identified 19 STP genes in pear ( Pyrus bretschneideri Rehd) and classified them into four phylogenetic groups (I–IV), all containing the conserved Sugar_tr domain. Transcriptome analysis showed that the expression peak of PbrSTP10 in the fruit flesh coincided with the period of rapid sugar accumulation. Promoter activity assays confirmed elevated transcription of PbrSTP10 at this stage. Functional complementation in a sugar uptake-deficient yeast strain and subcellular localization assays demonstrated that PbrSTP10 is a plasma membrane-localized transporter mediating proton-dependent fructose and glucose uptake. Further functional analyses indicated that overexpression of PbrSTP10 significantly increased the fructose and glucose contents in tomato fruits, pear fruits, and pear calli. Weighted gene co-expression network analysis (WGCNA) centered on PbrSTP10 identified several putative co-regulators of sugar accumulation. Collectively, these results provide valuable genetic resources and mechanistic insights for leveraging STPs to enhance pear fruit quality.