FLAVIN‐BINDING KELCH REPEAT F‐BOX 1 (FKF1) encodes an F‐box protein that regulates photoperiod flowering in Arabidopsis under long‐day conditions (LDs). Gibberellin (GA) is also important for regulating flowering under LDs. However, how FKF1 and the GA pathway work in concert in regulating flowering is not fully understood. Here, we showed that the mutation of FKF1 could cause accumulation of DELLA proteins, which are crucial repressors in GA signaling pathway, thereby reducing plant sensitivity to GA in flowering. Both in vitro and in vivo biochemical analyses demonstrated that FKF1 directly interacted with DELLA proteins. Furthermore, we showed that FKF1 promoted ubiquitination and degradation of DELLA proteins. Analysis of genetic data revealed that FKF1 acted partially through DELLAs to regulate flowering under LDs. In addition, DELLAs exerted a negative feedback on FKF1 expression. Collectively, these findings demonstrate that FKF1 promotes flowering partially by negatively regulating DELLA protein stability under LDs, and suggesting a potential mechanism linking the FKF1 to the GA signaling DELLA proteins.

中文翻译：

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FKF1 F-box蛋白通过在拟南芥中在长期光周期下负调节DELLA蛋白的稳定性来部分促进开花。

黄素键合的生菜重复F-BOX 1（FKF1）编码一个F-box蛋白，该蛋白在长日照条件下（LDs）调节拟南芥中的光周期开花。赤霉素（GA）对于调节LDs下的开花也很重要。但是，还没有完全了解FKF1和GA途径如何共同调节开花。在这里，我们表明FKF1的突变可能会引起DELLA蛋白的积累，而DELLA蛋白是GA信号通路中的关键阻遏物，从而降低了植物对开花时GA的敏感性。二者在体外和体内生化分析表明FKF1直接与DELLA蛋白相互作用。此外，我们表明FKF1促进DELLA蛋白的泛素化和降解。遗传数据分析表明，FKF1通过DELLAs部分作用来调节LDs下的开花。此外，DELLAs对FKF1表达产生负反馈。总体而言，这些发现表明FKF1通过负调节LDs下的DELLA蛋白稳定性来部分促进开花，并暗示了将FKF1与GA信号DELLA蛋白连接的潜在机制。