Genome-Wide Analysis of Grapevine Ascorbate Oxidase Genes Identifies VaAAO7 in Vitis amurensis as a Positive Regulator of Botrytis cinerea Resistance

Ascorbate oxidases (AAOs) are key regulators of extracellular redox homeostasis and plant stress responses, but their roles in grapevine defense remain unclear. Here, we performed a genome-wide analysis and characterization of the AAO gene family in grapevine Vitis amurensis, identifying 10 VaAAO genes that are unevenly distributed across six chromosomes, with notable clustering on chromosome 7. Promoter analysis revealed multiple phytohormone- and stress-responsive cis-elements (e.g., ARE, STRE, and TCA-element) and transcription factor binding sites (e.g., MYC/MYB, and WRKY), suggesting involvement in redox- and stress-related signaling pathways. Analysis of previously published transcriptomic data under Botrytis cinerea infection identified VaAAO7 as a key pathogen-responsive gene. VaAAO7 was rapidly induced by H2O2, and its transient ectopic overexpression in susceptible V. vinifera ‘Red Globe’ leaves significantly reduced lesion development. Together, these results demonstrate that VaAAO7 functions as a positive regulator of B. cinerea resistance and highlight its potential for genetic engineering to enhance systemic defense and develop disease-resistant grapevine cultivars.