Transcriptome Analysis of 'Kyoho' Grapevine Leaves Identifies Heat Response Genes Involved in the Transcriptional Regulation of Photosynthesis and Abscisic Acid

Grapevine is a popular cultivated fruit throughout the world and heat stress is one of the most serious threats to viticulture. However, transcriptional responses, such as molecular properties of photosynthesis and abscisic acid biosynthesis, metabolism and signal transduction pathway of grapevine to heat stress, are still poorly understood. In this study, RNA-seq was carried out for thermostabilized grapevine 'Kyoho' leaves. Results showed that 685 and 469 genes were commonly down-regulated and up-regulated at three sampling time-points. The light-dependent reactions of photosynthesis was significantly enriched in up-regulated DEGs at 1 hpt and down-regulated DEGs at R24 hpt. Heat stress impaired the photosynthetic capacity of grapevine leaves, and there was a significant positive relationship between photosynthesis and stomatal conductance at short-term post-heat stress treatment, but the inhibition of HS on Pn was non-stomata limitation for a longer period. Photosystem (PS)II was more sensitive to heat stress than PSI, and PsbP, as well as Psb28, played important roles in response to heat stress. The abscisic acid (ABA) content in heat-stress-treated Kyoho plants was higher than that in the control at 1 hpt, but less in heat-stress-treated plants at 4 and R24 hpt, which was regulated by numerous genes involved in the ABA biosynthesis and catabolism pathways. These results help to understand the influence of heat stress on photosynthesis and ABA biosynthesis, metabolism and signal transduction pathway.