Preharvest application of MeJA enhancing the quality of postharvest grape berries via regulating terpenes biosynthesis and phenylpropanoid metabolisms

Methyl jasmonate (MeJA) is an important phytohormone that regulates the development of grape, but the effect and underpin mechanism of its preharvest application on secondary metabolites accumulation in postharvest grape berries are still unclear. In this study, the transcriptome profiles combined with metabolic components analysis were used to determine the effect of preharvest MeJA application on the quality formation of postharvest rose-flavor table grape Shine Muscat. The results indicated that preharvest MeJA treatment had no significant effect on TSS content, but had a down-regulation effect on the accumulation of reducing sugar and titratable acid in the berries. The content of chlorophylls and carotenoids in treated berries was significantly higher than that of the control. Many phenolic components, such as trans-ferulic acid, resveratrol, quercetin, and kaempferol, were sensitive to MeJA and their contents were also significantly higher than that of the control under MeJA treatments during the shelf life. Compared with other volatile aroma components, terpenoid components were more sensitive to preharvest MeJA signals, the content of which presented an overall upward trend with increasing MeJA concentration and prolonging storage time. Furthermore, most of the differentially expressed genes in the general phenylpropanoid pathway and terpenoid biosynthesis pathway were up-regulated responding to MeJA signals. The most upregulated regulatory factors, such as VvWRKY72, VvMYB24, and VvWRI1, may be involved in MeJA signal transduction and regulation. Preharvest MeJA may be an effective technique for enhancing the quality of postharvest Shine Muscat grape berries, with its positive effect on enhancing the characteristic aroma and nutritional components.