Zhao Hongyun, Nie Kaili, Zhou Huapeng, Yan Xiaojing, Zhan Qidi, Zheng Yuan, Song Chun-Peng
State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, 475001, China.
Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610064, China.
New Phytol. 2020 Oct;228(2):596-608. doi: 10.1111/nph.16713. Epub 2020 Jul 4.
As abscisic acid (ABA) receptors, PYR1/PYL/RCAR (PYLs) play important roles in ABA-mediated seed germination, but the regulation of PYLs in this process, especially at the transcriptional level, remains unclear. In this study, we found that expression of 11 of 14 PYLs changes significantly during seed germination and is affected by exogenous ABA. Two PYLs, PYL11 and PYL12, both of which are expressed specifically in mature seeds, positively modulate ABA-mediated seed germination. However, ABI5 was found to modulate the PYL11- and PYL12-mediated ABA response. In the abi5-7 mutant, ABA hypersensitivity caused by PYL11 and PYL12 overexpression was totally or partially blocked. By contrast, ABI5 regulates the expression of PYL11 and PYL12 by directly binding to their promoters. Moreover, the expression of eight other PYLs is also affected during the germination of abi5 mutants. Promoter analysis revealed that an ABI5-binding region is present next to the TATA box or initiator box. Together, our data demonstrate the role of PYL11 and PYL12 in seed germination. In addition, the identification of PYLs as targets of ABI5 reveals a role of ABI5 in the feedback regulation of ABA-mediated seed germination.
作为脱落酸（ABA）受体，PYR1/PYL/RCAR（PYLs）在ABA介导的种子萌发过程中发挥重要作用，但PYLs在此过程中的调控机制，尤其是转录水平的调控，仍不清楚。在本研究中，我们发现14个PYLs中的11个在种子萌发过程中表达显著变化，并受外源ABA影响。两个PYLs，PYL11和PYL12，均在成熟种子中特异性表达，正向调控ABA介导的种子萌发。然而，发现ABI5可调节PYL11和PYL12介导的ABA反应。在abi5 - 7突变体中，由PYL11和PYL12过表达引起的ABA超敏反应被完全或部分阻断。相反，ABI5通过直接结合PYL11和PYL12的启动子来调节它们的表达。此外，在abi5突变体种子萌发过程中，其他8个PYLs的表达也受到影响。启动子分析表明，在TATA盒或起始子盒旁边存在一个ABI5结合区域。总之，我们的数据证明了PYL11和PYL12在种子萌发中的作用。此外，将PYLs鉴定为ABI5的靶标揭示了ABI5在ABA介导的种子萌发反馈调节中的作用。
