The Transcription Factor CcMYB330 Regulates Capsaicinoid Biosynthesis in Pepper Fruits.

Pepper is an important vegetable and economic crop, and the MYB family is one of the most numerous transcription factor families in plants, extensively participating in various biological processes such as plant growth, development, and stress resistance. In this study, CcMYB330 is identified as a differentially expressed gene in the pepper fruit, and CcMYB330 is expressed with higher expression levels in the placenta and pericarp at different development stages of pepper fruit. Analysis of the promoter cis-elements revealed that this gene contains not only core elements but also environmental factor response elements and plant hormone response elements. The silencing of CcMYB330 could reduce the capsaicinoid accumulation in pepper fruit, while the overexpression of CcMYB330 could increase capsaicinoid accumulation. Additionally, silencing or overexpressing CcMYB330 could regulate the expression of structural genes involved in capsaicinoid biosynthesis. In addition, through yeast one-hybrid experiments, we identified an interaction between CcMYB330 and the capsaicinoid biosynthesis structural gene CcPAL. Further evidence from EMSA experiments and dual luciferase assays confirmed that CcMYB330 can bind to the cis-element ACCAACAACCAAA in the CcPAL promoter. These results indicate that CcMYB330 may regulate the synthesis of capsaicinoids by modulating structural genes in the capsaicinoid biosynthesis pathway, providing new insights into the regulatory mechanisms of capsaicinoid synthesis.