Unraveling the Molecular Mechanisms of Bud-to-Flower Transition in Actinidia deliciosa cv. Guichang

Actinidia deliciosa cv. Guichang is a distinguished kiwifruit cultivar, whose phenotypic characteristics are influenced by the climatic conditions of Guizhou. The timing of flowering, which is subject to environmental factors, significantly impacts both yield and quality. This study aimed to elucidate the molecular mechanisms that regulate the transition from the bud stage to flowering in A. Guichang, particularly examining the roles of molecular signaling pathways. Transcriptomic analysis indicated that 6201 genes up-regulated and 5849 genes down-regulated between the bud and flowering stages. Key genes of A. Guichang associated with hormone signaling, such as AdPIF4, AdBSK, AdBRI1 and AdCYCD3, were identified as crucial players. Proteomic analysis identified a total of 10488 proteins, with AdBSK1 being regulated, while AdPIF4, AdBRI1 and AdCYCD3 exhibited no changed during the transition. A moderate positive correlation (Pearson correlation coefficient of 0.445) was observed between transcriptomic and proteomic expression levels. Over-expression AdBSK1 in Arabidopsis was found to promote earlier flowering by down-regulating AdFLC and up-regulating AdFT and AdSOC1.This study provides insights into the molecular regulation of the bud-to-flowering transition in A. Guichang, highlighting the complex interactions between hormonal pathways, key genes and proteins. The results have important implications for enhancing the understanding and potential manipulation of flowering time to improve fruit yield and quality.