Hu_2026_Plant.Physiol.Biochem_234_111294

Vitamin E (tocopherol) is a crucial antioxidant for both human health and plant adaptation to abiotic stress. Its biosynthesis relies on phytol, a moiety largely derived from chlorophyll degradation by members of the alpha/beta hydrolase (ABH) superfamily. While genes like CLDs, PPH, and VTE7 have been characterized in model plants, their functions in melon (Cucumis melo L.) remain unknown. Here, we performed a genome-wide analysis and identified five ABH family genes in melon: CmCLD1/2/3, CmPPH, and CmVTE7. Phylogenetic and motif analyses revealed both functional conservation and diversification within this family. Promoter analysis indicated that these genes possess numerous cis-elements responsive to light, hormones, and abiotic stresses. We further characterized CmVTE7, confirming its plastid localization and its distinct, broad expression profile across melon tissues. Ectopic overexpression of CmVTE7 in Arabidopsis robustly enhanced leaf tocopherol content by 1.5- to 3-fold. RNA-seq analysis revealed that CmVTE7 overexpression upregulates genes involved in the tocopherol biosynthesis pathway and a suite of heat-shock proteins. Consequently, transgenic Arabidopsis lines and transiently expressed melons exhibited dramatically improved survival rates under severe heat stress compared to controls. Our findings demonstrate that CmVTE7 is a key player that simultaneously enhances tocopherol accumulation and thermotolerance, providing a potential valuable genetic resource for breeding melon varieties with improved nutritional value and climate resilience.