Methyl jasmonate promotes suberin biosynthesis by stimulating transcriptional activation of AchMYC2 on AchFHT in wound healing of kiwifruit

Abstract

Suberin consisting of the polyaliphatic and polyphenolic domain confers the hydrophobic barrier of wound fruit and vegetables, providing essential protection from excessive water loss, ion outflow and pathogen invasion. The ω-hydroxyacid/fatty alcohol hydroxycinnamoyl transferase (FHT) is required for cross-linking of the polyaliphatic and polyphenolic domain in suberin biosynthesis. The transcription factor AchMYC2 acts as a positive activator in suberin biosynthesis but it is not known how it interacts with AchFHT in kiwifruit. In this study, overexpression of AchFHT in kiwifruit increased accumulation of suberin monomers, such as ferulate and ω-hydroxyacids. Yeast one-hybrid (Y1H) and dual-luciferase reporter (DLR) assays showed that AchMYC2 activated AchFHT transcript via interacting with the gene promoter. Overexpression of AchMYC2 in kiwifruit resulted in the upregulation of AchFHT, the accumulation of FHT protein and suberin monomers. Further, using yeast two-hybrid (Y2H) assay screened a jasmonate ZIM-domain protein (AchJAZ1, a key repressor of JA signaling pathway) which interacted with AchMYC2. Methyl jasmonate (MeJA) treatment increased expression levels of AchMYC2 and AchFHT, and the content of FHT protein, accompanying by the rapid wound healing process, as indicated by rapid suberin deposition, the reduced weight loss and relative electrolyte leakage. These results indicate that AchMYC2 activates AchFHT transcript to involve in MeJA-mediated suberin biosynthesis in wound healing of kiwifruit.