SlATG8f enhances tomato thermotolerance and fruit quality via autophagy and HS pathways

Plant responses to high-temperature stress involve dynamic and complex changes in physiology, biochemistry, and gene expression. Autophagy, a highly conserved intracellular degradation system, facilitates the removal and recycling of damaged cytoplasmic components such as proteins and organelles. It plays an essential role in plant growth, development, and adaptation to various stresses. Although the functions of many autophagy-related genes under high-temperature stress have been characterized, the role of SlATG8f, a key member of the SlATG8 family in tomato, remains poorly understood. In this study, we generated SlATG8f-Overexpressing tomato lines using the recombinant vector pBWA(V)HS. Using quantitative reverse transcription polymerase chain reaction (qRT-PCR), we analyzed physiological indices and expression levels of ATG8 family members and heat shock protein-related genes in fruits of wild-type (WT) and SlATG8f-overexpressing plants across four developmental stages under high-temperature stress. Our results indicate that overexpression of SlATG8f upregulates the expression of autophagy-related and heat shock protein genes, promotes early fruit ripening, and improves fruit quality under high-temperature stress. These findings reveal a regulatory role for SlATG8f in maintaining tomato fruit quality under heat stress and provide a theoretical foundation for tomato variety improvement.