Deciphering Grape Berry Peel Resistance to <i>Botrytis cinerea</i>: A Transcriptomic and Metabolomic Perspective

The fruit peel serves as the frontline defense of grapes against pathogens like <i>Botrytis cinerea</i>, yet its defense mechanisms remain poorly understood. This study reveals novel resistance mechanisms underlying peel immunity through comparative transcriptomic and metabolomic analysis of <i>Vitis amurensis</i> "Bei Binghong" (BH) and <i>V. vinifera</i> "Red Globe" (RG). The analysis identified 1277 differentially expressed genes (DEGs) and 38 differentially accumulated metabolites (DAMs), primarily associated with secondary metabolic processes and plant hormone signaling pathways. Weighted gene coexpression network analysis (WGCNA) uncovered three key modules and several novel hub genes. Crucially, transcriptomic profiling identified <i>VaWRKY20</i> as a central regulator. Postinfection, upregulated genes and metabolites were involved in salicylic acid (SA), lignin, and stilbene biosynthesis in BH, as well as enhanced resistance through overexpression of <i>VaWRKY20</i>. A conceptual model for <i>V. amurensis</i> defense against <i>B. cinerea</i> was proposed, providing novel insights into grapevine defense mechanisms.