The roles of brassinosteroids and methyl jasmonate on postharvest grape by regulating the interaction between VvDWF4 and VvTIFY 5 A

Brassinosteroids (BRs) and methyl jasmonate (MeJA) are known for the regulation of plant development, and the crosstalk between them is important for plant growth. However, the interaction between them in the development of postharvest fruit is unresolved. We found that BR treatment enhanced the accumulation of sugar composition and aroma content, reduced the content of organic acids (such as tartaric acid) and promoted the coloring of grape callus. After the application of MeJA, the acidity increased and the sugar content decreased. The physiological data showed that exogenous BR also attenuated the JA inhibition of postharvest ripening in grape. DWF4 is a key enzyme in the BR biosynthetic pathway, and it can effectively regulate the content of endogenous BRs. TIFY 5 A, which belongs to the Jasmonate ZIM-domain (JAZ) family, can be baited by DWF4 through the Y2H experiment. TIFY 5 A represses the expression of dihydroflavonol-4-reductase (DFR) which plays a key role in the synthesis of anthocyanins, while this will be alleviated by VvDWF4. The interaction between TIFY 5 A and DWF4 contributes to the cross talk between JA and BR signalling pathways. This is also verified by the transgenic experimental results. The results in this paper provides a new insight into the relationship between BR and JA signalling pathways, which is important to the regulation of the postharvest ripening of grape. ●Brassinosteroids (BRs) can promote the postharvest ripening of grape, while methyl jasmonate (MeJA) has significant antagonism to BRs.●The interaction between TIFY 5A and DWF4 contributes to the cross talk between JA and BR signalling pathways.●DWF4 plays a reverse role with that of TIFY 5A in the expression of DFR which plays a key role in the synthesis of anthocyanins.