Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany.
Centre for Plant Molecular Biology, University of Tübingen, Tübingen, Germany.
Nat Commun. 2022 Mar 29;13(1):1656. doi: 10.1038/s41467-022-29315-3.
Seed germination is a critical step in the life cycle of plants controlled by the phytohormones abscisic acid (ABA) and gibberellin (GA), and by phytochromes, an important class of photoreceptors in plants. Here we show that light-dependent germination is enhanced in mutants deficient in the AP2/ERF transcription factors ERF55 and ERF58. Light-activated phytochromes repress ERF55/ERF58 expression and directly bind ERF55/ERF58 to displace them from the promoter of PIF1 and SOM, genes encoding transcriptional regulators that prevent the completion of germination. The same mechanism controls the expression of genes that encode ABA or GA metabolic enzymes to decrease levels of ABA and possibly increase levels of GA. Interestingly, ERF55 and ERF58 are themselves under transcriptional control of ABA and GA, suggesting that they are part of a self-reinforcing signalling loop which controls the completion of germination. Overall, we identified a role of ERF55/ERF58 in phytochrome-mediated regulation of germination completion.
种子萌发是植物生命周期中的一个关键步骤，受脱落酸（ABA）和赤霉素（GA）等植物激素以及光敏色素（phytochrome）的调控，后者是植物中一类重要的光受体。在这里，我们发现，在缺乏 AP2/ERF 转录因子 ERF55 和 ERF58 的突变体中，光依赖的萌发得到增强。光激活的光敏色素抑制 ERF55/ERF58 的表达，并直接与 ERF55/ERF58 结合，将其从 PIF1 和 SOM 基因的启动子上置换出来，PIF1 和 SOM 基因编码转录调节剂，阻止萌发的完成。同样的机制控制编码 ABA 或 GA 代谢酶的基因的表达，以降低 ABA 的水平并可能增加 GA 的水平。有趣的是，ERF55 和 ERF58 本身受 ABA 和 GA 的转录调控，表明它们是自我强化信号回路的一部分，该回路控制萌发的完成。总的来说，我们确定了 ERF55/ERF58 在光敏色素介导的萌发完成调控中的作用。
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