Although ABSCISIC ACID INSENSITIVE 4 (ABI4) was initially demonstrated as a key positive regulator in the phytohormone abscisic acid (ABA) signaling cascade, multiple studies have now shown that it is actually involved in the regulation of several other cascades, including diverse phytohormone biogenesis and signaling pathways, various developmental processes (such as seed dormancy and germination, seedling establishment, and root development), disease resistance and lipid metabolism. Consistent with its versatile biological functions, ABI4 either activates or represses transcription of its target genes. The upstream regulators of ABI4 at both the transcription and post-transcription levels have also been documented in recent years. Consequently, a complicated network consisting of the direct target genes and upstream regulators of ABI4, through which ABI4 participates in several phytohormone crosstalk networks, has been generated. In this review, we summarize current understanding of the sophisticated ABI4-mediated molecular networks, mainly focusing on diverse phytohormone (including ABA, gibberellin, cytokinin, ethylene, auxin, and jasmonic acid) crosstalks. We also discuss the potential mechanisms through which ABI4 receives the ABA signal, focusing on protein phosphorylation modification events.

尽管脱落酸不敏感 4 (ABI4) 最初被证明是植物激素脱落酸 (ABA) 信号级联中的关键正调节因子，但多项研究现已表明，它实际上参与了其他几个级联的调节，包括多种植物激素生物合成和信号通路、各种发育过程（如种子休眠和发芽、幼苗建立和根部发育）、抗病性和脂质代谢。与其多功能的生物学功能一致，ABI4 可以激活或抑制其靶基因的转录。近年来，ABI4 在转录和转录后水平上的上游调节因子也已被记录。因此，形成了一个由 ABI4 的直接靶基因和上游调节因子组成的复杂网络，ABI4 通过该网络参与多个植物激素串扰网络。在这篇综述中，我们总结了目前对复杂的 ABI4 介导的分子网络的理解，主要关注多种植物激素（包括 ABA、赤霉素、细胞分裂素、乙烯、生长素和茉莉酸）的串扰。我们还讨论了 ABI4 接收 ABA 信号的潜在机制，重点关注蛋白质磷酸化修饰事件。