ABI4 represses the expression of type-A ARRs to inhibit seed germination in Arabidopsis
ABI4 represses the expression of type-A ARRs to inhibit seed germination in Arabidopsis
复制标题
ABI4 抑制 A 型 ARR 的表达从而抑制拟南芥种子萌发
DOI：
10.1111/tpj.13389
复制
发表时间：
2017-01-01
期刊：
影响因子：
7.2
通讯作者：
Shi, Yiting
中科院分区：
文献类型：
--
作者：
Huang, Xiaozhen;Zhang, Xiaoyan;Shi, Yiting
植物激素脱落酸（阿坝）在调节种子萌发和萌发后生长中起着至关重要的作用。脱落酸不敏感4（Abscisic Acid Insensitive 4，ABI 4）是一种APETALA 2（AP 2）型转录因子，在ABA介导的种子萌发抑制中起重要作用。细胞分裂素通过拮抗阿坝信号促进种子萌发和幼苗生长。然而，阿坝和细胞分裂素信号在种子萌发过程中的相互作用仍不清楚。在这里，我们报告阿坝信号下调拟南芥反应调节因子（ARRs），一类细胞分裂素诱导的基因，在种子萌发和子叶绿化。我们发现，外源阿坝的应用抑制了拟南芥种子和幼苗中A型ARRs的表达。在A型ARR家族成员中，ARR 6、ARR 7和ARR 15的表达在ABA缺陷突变体中上调，表明A型ARR的转录抑制需要阿坝信号通路。这些ARRs的单个和多个突变导致在萌发和子叶绿化过程中阿坝敏感性增加; ARR 7或ARR 15的过表达导致ABA不敏感表型。这些观察结果表明，A型ARRs抑制种子萌发和子叶绿化过程中的阿坝反应。进一步的分析表明，ABI 4通过直接与ARR 6、ARR 7和ARR 15的启动子结合来负调控ARR 6、ARR 7和ARR 15的转录。遗传分析表明，ARR 7和ARR 15的功能丧失突变部分挽救了abi 4 -1的阿坝不敏感性。因此，本研究揭示ABI 4通过抑制A型ARRs的转录来抑制种子萌发和子叶绿化，在阿坝和细胞分裂素信号传导中起关键作用。
The plant hormone abscisic acid (ABA) plays a crucial role in regulating seed germination and post-germination growth. ABSCISIC ACID INSENSITIVE4 (ABI4), an APETALA2 (AP2)-type transcription factor, is required for the ABA-mediated inhibition of seed germination. Cytokinins promote seed germination and seedling growth by antagonizing ABA signaling. However, the interaction between ABA and cytokinin signaling during seed germination remains unclear. Here, we report that ABA signaling downregulates Arabidopsis response regulators (ARRs), a class of cytokinin-inducible genes, during seed germination and cotyledon greening. We found that the application of exogenous ABA repressed the expression of type-A ARRs in Arabidopsis seeds and seedlings. Among the type-A ARR family members, the expression of ARR6, ARR7 and ARR15 was upregulated in ABA-deficient mutants, indicating that the transcriptional inhibition of type-A ARRs requires the ABA signaling pathway. Single and multiple mutations of these ARRs resulted in increased ABA sensitivity during germination and cotyledon greening; overexpression of ARR7 or ARR15 led to an ABA-insensitive phenotype. These observations suggest that type-A ARRs inhibit the ABA response during seed germination and cotyledon greening. Further analysis showed that ABI4 negatively regulated the transcription of ARR6, ARR7 and ARR15 by directly binding to their promoters. Genetic analysis showed that loss-of- function mutations of ARR7 and ARR15 partially rescued the ABA insensitivity of abi4-1. Thus, this study revealed that ABI4 plays a key role in ABA and cytokinin signaling by inhibiting the transcription of type-A ARRs to inhibit seed germination and cotyledon greening.