Study on mechanism of earlier flowering in Actinidia. Hanhong and Actinidia. Guichang

Background/Objectives: The Chinese kiwifruit (Actinidia chinensis) is an economically significant species, characterized by a diverse array of cultivars that vary in flesh pigmentation and maturation timelines. Effective modulation of flowering is crucial for optimizing both yield and fruit quality, which involves intricate hormonal signaling networks. Methods: This study investigated the molecular mechanisms underlying bud and floral development in the Actinidia. Hanhong and Actinidia. Guichang cultivars through transcriptomic and proteomic approaches. Results: Our analysis demonstrated that gibberellin levels rise as bud transition into flowering in kiwifruit. The AdPIF4 was identified as a promoter of the bud-to-flower transition, whereas AdRGA functions as a repressor. Additionally, AdGID1 and AdGID2 exhibit distinct roles during the bud and flowering stages. AdRGA negatively regulates flowering by down-regulating the transcript expression level of FT, while AdAHP5 positively regulates flowering by up-regulating the transcript expression level FT and SOC1. Conclusions: This study suggests that AdRGA and AdAHP5 are critical for the earlier flowering of A. Hanhong, particularly when compared to Guichang.