LAUSR

Abstract The frequent occurrence of extremely high temperatures can severely affect agricultural production. In grapevines, elevated temperatures can cause irreversible damage during the fruit ripening period. The suggested main approach for addressing this challenge is breeding high-temperature-resistant varieties, which makes it critical to identify key genes involved in the heat stress molecular regulatory network of grapevines. In this study, we exposed the saplings of two grapevine varieties, “Shenfeng” and “Shenhua,” to 45 °C for 3 and 6 h. After 3 h of temperature stress, the leaves of “Shenfeng” appeared dehydrated, and after 6 h, the whole plants had dried up. In contrast, the leaves and the apex of “Shenhua” stem showed only mild water loss and wilt symptoms after 6 h, indicating that this cultivar has strong heat resistance. In response to the 45 °C high-temperature stress, and compared to their levels at 0 h, 822, 501, and 1161 genes showed differential expression levels in “Shenfeng” after 3 h and in “Shenhua” after 3 and 6 h of treatment, respectively; 233 of these genes showed differential expression patterns in the three comparisons. Statistical analysis of these differentially expressed genes revealed that the most up-regulated metabolic pathways in both cultivars were endoplasmic reticulum protein processing and plant hormone signal transduction. Our data indicates that among heat shock transcription factor (HSF) family genes, the HSFA2 and HSFA7 were the most heat-sensitive, and that HSF and HSP cooperated to response adversity. Photosystem II (PSII) functioned more efficiently in heat-tolerant rather than in heat-sensitive grapevines, leading to differences in the PSII parameters and transcriptional levels of key PSII protein-coding genes between the cultivars. We can conclude that, in response to high-temperature stress, interactions among endogenous hormone-mediated plant defense processes and the ABA response pathway have great research value.