AdBSK1-Mediated Hormone Signaling Regulates Flowering Transition in Actinidia deliciosa 'Guichang'.

BACKGROUND: The Actinidia deliciosa cultivar 'Guichang' is a remarkable kiwifruit variety. The phenotypic traits of this variety are influenced by the climatic conditions in Guizhou. The flowering time, which is shaped by multiple environmental factors, has a substantial impact on both the fruit yield and quality. OBJECTIVES AND METHODS: This study was designed to explore the molecular mechanisms underlying the transition from bud to flowering in 'Guichang' through transcriptomic and proteomic analyses. RESULTS: The transcriptomic results revealed that 6201 genes were up-regulated, while 5849 genes were down-regulated during this transition. Key genes related to hormone signaling, such as AdPIF4, AdBSK, AdBRI1, and AdCYCD3, were recognized as crucial regulators. The proteomic analysis detected a total of 10,488 proteins. Among them, AdBSK1 was regulated, while AdPIF4, AdBRI1, and AdCYCD3 showed stable expressions. A moderate positive correlation (with a Pearson correlation coefficient of 0.445) was found between the expression levels of transcriptomics and proteomics. When AdBSK1 was over-expressed in Arabidopsis, it promoted earlier flowering. This was achieved by down-regulating FLC and up-regulating FT and SOC1. CONCLUSIONS: This study clarifies the molecular mechanisms involved in the bud-to-flowering transition in 'Guichang'. It emphasizes the intricate interactions among hormonal pathways, key genes, and proteins, which are consistent with the broader understanding of plant flowering regulation in recent research. These findings are significant for deepening our understanding of, and potentially controlling, the flowering mechanisms.