Berry color is a critical determinant of grape quality and market value. While the genetic basis of skin color has been extensively studied, the regulatory network controlling flesh coloration remains largely uncharacterized. To systematically dissect the independent genetic architectures underlying these traits, we performed a genome-wide association study (GWAS) on 130 grape accessions, integrated with spatiotemporal expression profiling, subcellular localization, and functional validation. Our analysis revealed distinct genetic loci for skin and flesh color, confirming their independent regulation. For skin color, GWAS robustly validated VvMYBA2 as a major locus, explaining up to 51.5% of the phenotypic variance. More importantly, for flesh color, we identified and prioritized VvF3′M (Flavonoid 3′-monooxygenase) as a key candidate gene. Heterologous overexpression of VvF3′M in tobacco resulted in a profound 13.5-fold increase in anthocyanin content, suggesting its potential role as a rate-limiting enzyme in flesh pigmentation. Intriguingly, VvF3′M-overexpressing plants also exhibited a significant increase in flower number, suggesting a novel role beyond pigment biosynthesis. This study provides a comprehensive genetic and functional framework for understanding berry coloration, identifies VvF3′M as a prime target for breeding red-fleshed grapes, and reveals unexpected crosstalk between color metabolism and reproductive development.

The coloration of vegetative organs in grapevine (Vitis vinifera L.) is an important phenotypic trait associated with environmental responsiveness and stress adaptation; however, its genetic regulatory mechanisms remain poorly understood. To systematically elucidate the genetic basis of vegetative coloration, a genome-wide association study (GWAS) was performed using 151 grapevine accessions, integrating high-depth whole-genome resequencing data with phenotypic evaluations of eight coloration traits across two consecutive years (2023–2024). Using a mixed linear model (MLM), 13 stable and significant SNP loci were identified on chromosomes 3, 5, 6, 13, 14, 15, 16, and 18, explaining 13.28–19.35% of the phenotypic variation. Within ±15 kb of these loci, 16 candidate genes were identified. qRT-PCR analysis of key candidates revealed that VIT_06s0004g03620 (mitogen-activated protein kinase), VIT_16s0039g01900 (MYB-like domain-containing protein), and VIT_14s0083g01050 (MADS-box protein 2) showed significant positive correlations between expression levels and coloration intensity, with distinct expression patterns among accessions exhibiting different coloration grades. These genes are likely involved in the regulation of anthocyanin accumulation. Collectively, this study elucidates the genomic architecture underlying vegetative organ coloration in grapevine and provides valuable candidate genes and SNP markers for functional validation and molecular-assisted breeding.

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.