Expression of Flavonoid and Stilbene Synthesis Genes in Grape Berries is Affected by High Temperature

Increased temperatures caused by climate change inhibit berry skin coloration during the ripening season of grape cultivation. In this study, we analyzed the expression patterns of flavonoid synthesis genes involved in color and stilbene compound synthesis genes at the transcript level in 'Campbell Early' grapes subjected to different temperatures. The expression of chalcone isomerase (CHI), leucoanthocyanidin dioxygenase (LDOX, and trans-cinnamate 4-monooxygenase (CYP73A) genes increased in all temperature conditions; however, their expression was lower at 30-35 degrees C than 25 degrees C, and was much lower at 35 degrees C. Indeed, the expression of most tested genes was lower at 35 degrees C than other temperatures. Additionally, subjecting grapes to high temperatures in the initial stage of veraison significantly reduced the synthesis and accumulation of anthocyanins. Moreover, the expression of the resveratrol synthase (STS1) gene was gradually induced at all temperature treatments, but decreased at 48 h and the expression at 25 degrees C was inhibited when compared to expression at 35 degrees C. Expression of stilbe synthasela-1(STS11), STS1a-2 (STS12), and STS1a-3 (STS13) genes had similar expression patterns at all temperatures, which decreased with increasing temperature and was suppressed at 35 degrees C compared to 25 degrees C. These results can be used to understand the response mechanisms of grapes to high temperature stress at the molecular level, as well as to provide information for grape breeding programs and viticulture to overcome obstacles caused by high temperatures associated with global climate change.