Abstract: 【Objective】 The aims of the study were to analyze the genes involved in the regulation of grape anthocyanin accumulation and fruit quality by 24-Epibrassinolide under high-temperature stress, and to explore the molecular mechanism of EBR regulation anthocyanin accumulation in grapes under high-temperature stress. 【Method】 'Cabernet Sauvignon' grapes were treated with high-temperature stress using infrared emitter, and sprayed 0.6 mg?L^-1 of EBR before the veraison. The contents of total anthocyanins, total sugar, reducing sugar and sucrose were quantified using the ultraviolet visible spectrophotometer. The mechanism of EBR-mediated accumulation of anthocyanin under high-temperature stress was analyzed by transcriptome sequencing. 【Result】 Starting from veraison , the anthocyanin content increased gradually under various treatments. At maturity, the total anthocyanin content in the high temperature group (HT) was significantly lower than that in the control group (CK), and the anthocyanin content in the high temperature and 24-Epibrassinolide group (HTE) was higher than that in the HT group and lower than CK group. Under HT treatment, the accumulation pattern of total sugar, reducing sugar and sucrose was similar to that of anthocyanins and lower than those of CK group at maturity stage. Compared with HT group, the contents of various sugars in HTE group were increased. The differences in transcriptome levels of 'Cabernet Sauvignon' fruits under the three treatments were analyzed. Through GO and KEGG enrichment, fourteen differential genes related to sucrose and starch metabolic pathways, among which 10 genes were significantly up-regulated and 4 genes were significantly down-regulated under HT and HTE treatments. The expressions of 11 genes are different in the phenylpropane metabolic pathway. Seven genes involved in anthocyanin synthesis were upregulated under the HT treatment, and 4 genes involved in lignin synthesis were significantly upregulated under the HT treatment, indicating that high temperature may promote lignin synthesis and reduce the accumulation of anthocyanins. In the endogenous hormone signaling pathway, the expression of the ABA signaling receptor genes PP2C and SnRK2 was significantly increased under high-temperature stress, and may be involved in regulating the synthesis of grape anthocyanin under high-temperature stress together with EBR. The expression patterns of some differential genes were verified by qRT-PCR, which confirmed the accuracy of transcriptome data. 【Conclusion】 EBR alleviated the inhibitory effect of high temperature stress on grapevine anthocyanin accumulation, probably due to the fact that EBR reduced the expression of lignin-related genes and changed the expression pattern of grape endogenous hormone signal transduction genes.

Key words: Vitis vinifera L. cv 'Cabernet Sauvignon', brassinosterids, high-temperature, anthocyanin, RNA-seq