Regulation of flowering by endogenous and environmental signals ensures that reproduction occurs under optimal conditions to maximize reproductive success. Involvement of the growth regulator gibberellin (GA) in the control of flowering by environmental cues varies among species. Arabis alpina Pajares, a model perennial member of the Brassicaceae, only undergoes floral induction during vernalization, allowing definition of the role of GA specifically in this process. The transcription factor PERPETUAL FLOWERING1 (PEP1) represses flowering until its mRNA levels are reduced during vernalization. Genome-wide analyses of PEP1 targets identified genes involved in GA metabolism and signaling, and many of the binding sites in these genes were specific to the A. alpina lineage. Here, we show that the pep1 mutant exhibits an elongated-stem phenotype, similar to that caused by treatment with exogenous GA, consistent with PEP1 repressing GA responses. Moreover, in comparison with the wild type, the pep1 mutant contains higher GA₄ levels and is more sensitive to GA prior to vernalization. Upon exposure to cold temperatures, GA levels fall to low levels in the pep1 mutant and in wild-type plants, but GA still promotes floral induction and the transcription of floral meristem identity genes during vernalization. Reducing GA levels strongly impairs flowering and inflorescence development in response to short vernalization treatments, but longer treatments overcome the requirement for GA. Thus, GA accelerates the floral transition during vernalization in A. alpina, the down-regulation of PEP1 likely increases GA sensitivity, and GA responses contribute to determining the length of vernalization required for flowering and reproduction.

通过内源和环境信号调节开花可确保繁殖在最佳条件下进行，从而最大限度地提高繁殖成功率。生长调节剂赤霉素（GA）通过环境因素控制开花的程度因物种而异。高山南芥(Arabis alpina Pajares) 是十字花科多年生植物的典范，仅在春化过程中进行花诱导，从而可以明确 GA 在此过程中的具体作用。转录因子 PERPETUAL FLOWERING1 (PEP1) 会抑制开花，直到其 mRNA 水平在春化过程中降低。对 PEP1 靶标的全基因组分析确定了参与 GA 代谢和信号传导的基因，这些基因中的许多结合位点是 A. alpina谱系特有的。在这里，我们发现pep1突变体表现出细长的茎表型，类似于用外源 GA 处理引起的表型，与 PEP1 抑制 GA 反应一致。此外，与野生型相比，pep1突变体含有更高的GA ₄水平并且在春化前对GA更敏感。暴露于低温后，pep1突变体和野生型植物中的 GA 水平降至较低水平，但 GA 仍然在春化过程中促进花诱导和花分生组织识别基因的转录。降低 GA 水平会严重损害短期春化处理的开花和花序发育，但较长的处理克服了对 GA 的需求。因此，GA 加速了A. alpina春化过程中的花转变， PEP1的下调可能会增加 GA 敏感性，并且 GA 反应有助于确定开花和繁殖所需的春化长度。