Arabidopsis EIN2 represses ABA responses during germination and early seedling growth by inactivating HLS1 protein independently of the canonical ethylene pathway
Arabidopsis EIN2 represses ABA responses during germination and early seedling growth by inactivating HLS1 protein independently of the canonical ethylene pathway
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DOI：
10.1111/tpj.16335
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发表时间：
2023-06-18
期刊：
影响因子：
7.2
通讯作者：
Guo，Hongwei
中科院分区：
文献类型：
--
作者：
Guo，Renkang;Wen，Xing;Guo，Hongwei
植物激素乙烯和脱落酸(ABA)的信号通路对种子萌发和早期成苗具有拮抗作用。然而，其潜在的分子机制仍不清楚。在拟南芥中，乙烯不敏感2(EIN2)定位于内质网(ER)，虽然其生化功能尚不清楚，但它将乙烯信号与关键转录因子EIN3和EIN3样蛋白1(EIL1)连接起来，导致乙烯反应基因的转录激活。在这项研究中，我们发现了EIN2在调节ABA反应中不依赖于EIN3/EIL1的作用。上位性分析表明，EIN2在ABA反应中的这一独特作用依赖于无钩1(HLS1)，组蛋白乙酰转移酶是ABA反应的正调控因子。蛋白质相互作用分析支持EIN2和HLS1在体外和体内的直接物理相互作用。EIN2功能缺失导致HLS1介导的ABA不敏感3(ABI3)和ABI5位点组蛋白乙酰化发生改变，从而促进种子萌发和幼苗早期生长过程中的基因表达和ABA反应，表明EIN2-HLS1模块参与了ABA反应。因此，我们的研究表明，EIN2通过抑制HLS1功能来调节ABA反应，而不依赖于典型的乙烯途径。这些发现揭示了乙烯和ABA信号之间相互拮抗的复杂调控机制，对于我们理解植物的生长发育具有重要意义。
The signaling pathways for the phytohormones ethylene and abscisic acid (ABA) have antagonistic effects on seed germination and early seedling establishment. However, the underlying molecular mechanisms remain unclear. InArabidopsis thaliana, ETHYLENE INSENSITIVE 2 (EIN2) localizes to the endoplasmic reticulum (ER); although its biochemical function is unknown, it connects the ethylene signal with the key transcription factors EIN3 and EIN3‐LIKE 1 (EIL1), leading to the transcriptional activation of ethylene‐responsive genes. In this study, we uncovered an EIN3/EIL1‐independent role for EIN2 in regulating the ABA response. Epistasis analysis demonstrated that this distinct role of EIN2 in the ABA response depends on HOOKLESS 1 (HLS1), the putative histone acetyltransferase acting as a positive regulator of ABA responses. Protein interaction assays supported a direct physical interaction between EIN2 and HLS1in vitroandin vivo. Loss of EIN2 function resulted in an alteration of HLS1‐mediated histone acetylation at theABA‐INSENSITIVE 3(ABI3) andABI5loci, which promotes gene expression and the ABA response during seed germination and early seedling growth, indicating that the EIN2–HLS1 module contributes to ABA responses. Our study thus revealed that EIN2 modulates ABA responses by repressing HLS1 function, independently of the canonical ethylene pathway. These findings shed light on the intricate regulatory mechanisms underling the antagonistic interactions between ethylene and ABA signaling, with significant implications for our understanding of plant growth and development.