Genome-Wide Identification of the BZR Gene Family and Expression Validation of VvBZR7 in Grape (Vitis vinifera L.)

Brassinazole-resistant (BZR) gene is a key transcription factor in the brassinosteroid signaling pathway and plays a critical role in regulating plant growth, development, and environmental stress responses. However, systematic studies on the BZR gene family in grape remain limited. In this study, eight BZR genes were identified in the grape genome, which were unevenly distributed across seven chromosomes and classified into four subfamilies. Bioinformatics analysis was performed to characterize their physicochemical properties, conserved motifs, chromosomal locations, and expression across tissues and in response to hormones. Further experimental results showed that VvBZR7 expression is induced by brassinosteroid and its inhibitor. Subcellular localization confirmed that VvBZR7 is localized in the nucleus. Transient overexpression assays demonstrated that VvBZR7 promotes the degradation of cell wall components, which reduces fruit firmness and consequently accelerates softening. These findings establish a foundation for elucidating the functional roles and regulatory mechanisms of the BZR gene family in grapevine.