Max Planck Institute for Plant Breeding Research, D50829 Cologne, Germany.
Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas, Universidad Politécnica de Valencia, 46022 Valencia, Spain.
Plant Physiol. 2019 Jul;180(3):1549-1563. doi: 10.1104/pp.19.00021. Epub 2019 May 16.
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. 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 lineage. Here, we show that the 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 mutant contains higher GA levels and is more sensitive to GA prior to vernalization. Upon exposure to cold temperatures, GA levels fall to low levels in the 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 , the down-regulation of likely increases GA sensitivity, and GA responses contribute to determining the length of vernalization required for flowering and reproduction.
内源性和环境信号对开花的调控确保了繁殖在最佳条件下进行，以最大限度地提高繁殖成功率。生长调节剂赤霉素（GA）在环境线索控制开花中的作用因物种而异。 Pajares 是拟南芥科的一种模式多年生植物，仅在春化过程中进行花诱导，从而可以明确 GA 在该过程中的具体作用。转录因子 PERPETUAL FLOWERING1（PEP1）抑制开花，直到其 mRNA 水平在春化过程中降低。PEP1 靶基因的全基因组分析鉴定了参与 GA 代谢和信号转导的基因，并且这些基因中的许多结合位点是特定于 谱系的。在这里，我们表明 突变体表现出伸长茎的表型，类似于外源 GA 处理引起的表型，这与 PEP1 抑制 GA 反应一致。此外，与野生型相比， 突变体含有更高水平的 GA，并且在春化之前对 GA 更敏感。暴露于低温下，GA 水平在 突变体和野生型植物中降至低水平，但 GA 仍在春化过程中促进花诱导和花分生组织身份基因的转录。降低 GA 水平强烈损害了对短春化处理的开花和花序发育，但更长的处理克服了对 GA 的需求。因此，GA 在 中加速了春化过程中的花转变， 下调可能增加了 GA 的敏感性，并且 GA 反应有助于确定开花和繁殖所需的春化时间长度。
