School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, 710012, China.
Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany.
J Exp Bot. 2022 Aug 11;73(14):4674-4682. doi: 10.1093/jxb/erac200.
Appropriate timing of seed germination is crucial for plant survival and has important implications for agricultural production. Timely germination relies on harmonious interactions between endogenous developmental signals, especially abscisic acid (ABA) and gibberellins (GAs), and environmental cues such as light. Recently, a series of investigations of a three-way crosstalk between phytochromes, ABA, and GAs in the regulation of seed germination demonstrated that the transcription factor ABSCISIC ACID INSENSITIVE 5 (ABI5) is a central mediator in the light-ABA/GA cascades. Here, we review current knowledge of ABI5 as a key player in light-, ABA-, and GA-signaling pathways that precisely control seed germination. We highlight recent advances in ABI5-related studies, focusing on the regulation of seed germination, which is strictly controlled at both the transcriptional and the protein levels by numerous light-regulated factors. We further discuss the components of ABA and GA signaling pathways that could regulate ABI5 during seed germination, including transcription factors, E3 ligases, protein kinases, and phosphatases. The precise molecular mechanisms by which ABI5 mediates ABA-GA antagonistic crosstalk during seed germination are also discussed. Finally, some potential research hotspots underlying ABI5-mediated seed germination regulatory networks are proposed.
种子萌发的适时性对植物的生存至关重要，对农业生产也有重要意义。适时萌发依赖于内源性发育信号（尤其是脱落酸(ABA)和赤霉素(GAs)）与环境线索（如光）之间的和谐相互作用。最近，一系列关于植物光敏色素、ABA 和 GAs 三方串扰在调控种子萌发中的研究表明，转录因子 ABA 不敏感 5（ABI5）是光-ABA/GA 级联反应中的一个核心介质。在这里，我们回顾了 ABI5 作为光、ABA 和 GA 信号通路中的关键因子的现有知识，这些信号通路精确控制着种子的萌发。我们强调了 ABI5 相关研究的最新进展，重点关注种子萌发的严格转录和蛋白水平调控，受众多光调控因子的调控。我们进一步讨论了 ABA 和 GA 信号通路中可能在种子萌发过程中调节 ABI5 的成分，包括转录因子、E3 连接酶、蛋白激酶和磷酸酶。还讨论了 ABI5 在种子萌发过程中介导 ABA-GA 拮抗串扰的精确分子机制。最后，提出了 ABI5 介导的种子萌发调控网络的一些潜在研究热点。
