FaMYB9 is involved in the regulation of C6 volatile biosynthesis in strawberry

Abstract

The large-scale untargeted proteomic and metabolomic studies were conducted in strawberry (Fragaria × ananassa) cv. Akihime fruit at five developmental stages. We found that some C6 volatiles highly contributed to the enrichment of volatiles at the red stage of strawberry fruit. We found that 12 genes involved in LOX pathway for volatile biosynthesis showed multiple patterns in protein abundance during fruit development and ripening, and 9 out of the 12 genes exhibited a significant increase in their relative expression levels at the red stage of fruit. We also found that the MYB9 gene (FaMYB9) expression level was positively correlated with the content of C6 volatiles (R = 0.989) and with the relative expression level and protein abundance of FaLOX5 at different strawberry fruit developmental stages (R = 0.954). The interaction between FaMYB9 and FaLOX5 was detected by yeast two-hybrid, co-immunoprecipitation (Co-IP), bimolecular fluorescence complementation (BiFC), and immunofluorescence (IF) analyses. Transient silencing of FaMYB9 delayed the fruit development and ripening, resulting in a significant decrease in the contents of C6 volatiles, while overexpression of FaMYB9 increased the fruit development and ripening and the contents of C6 volatiles in Akihime fruit. Therefore, FaMYB9 is positively involved in C6 volatile biosynthesis.