Grapes are prone to softening, which limits their shelf life and suitability for long-distance transport. This study explored the molecular mechanisms underlying the effects of the chemical preservatives gibberellin (GA₃) and the nitric oxide donor sodium nitroprusside (SNP) on grape firmness. Enhancing grape quality, prolonging shelf life, and extending market supply were key objectives. Using transcriptomic and physicochemical analyses, the study found that treatments with 3 mmol/L GA₃ and 20 μmol/L SNP significantly increased the firmness of ‘Yinhong’ grapes, thereby improving overall quality. The mechanisms of action, however, differed between the two treatments. GA₃ inhibited pectin degradation and promoted cellulose accumulation, whereas SNP enhanced lignin and cellulose accumulation, by modulating cell wall metabolism. Furthermore, transcription factors such as CYPs, NAC043, and WRKY33 were identified as key regulators working in concert with target genes to influence berry firmness. These findings highlight the critical roles of GA₃ and SNP in improving grape quality and extending storage potential.

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.

Aroma is a crucial quality trait in ornamental flowers; however, the molecular mechanisms by which hormones regulate fragrance in Rhododendron remain poorly understood. In this study, Gibberellin (GA₃)-treated petals of Rhododendron fortunei Lindl were used as experimental materials to integrate volatile metabolomics with RNA-seq analysis, aiming to investigate aroma changes and their underlying molecular regulatory mechanisms. We cloned and characterized RfHMGR1, which encodes a key enzyme in the Mevalonate (MVA) pathway, and verified its function. Subcellular localization analysis showed that the Green Fluorescent Protein (GFP) signal of the RfHMGR1-GFP fusion protein was mainly distributed in the cytoplasm. Transient overexpression of RfHMGR1 in petals of two Rhododendron species (R. fortunei and Rhododendron hybrida) significantly increased the accumulation of the terpenoid linalool, whereas gene silencing reduced linalool accumulation. Furthermore, the purified recombinant RfHMGR1 protein exhibited HMGR-specific reductase activity in vitro. Our results confirmed that GA₃ regulates the terpenoid fragrance of R. fortunei by targeting the MVA pathway gene RfHMGR1. Collectively, these findings provide new insights into the fragrance regulation mechanisms in R. fortunei and identify molecular targets for breeding strategies aimed at improving floral scent.

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.