Zhang Qi, Zhang Wei, Wei Jianbo, Gao Zhaoxu, Guan Jianing, Cui Zhibo, Wang Xiaoxue
Rice Research Institute, Shenyang Agricultural University, Shenyang 110866, China.
Biotechnology Research Institute, Heilongjiang Academy of Agricultural Sciences, Harbin 150086, China.
Plant Cell Physiol. 2022 Apr 19;63(4):494-507. doi: 10.1093/pcp/pcac014.
Abscisic acid (ABA) plays key roles in plant development and responses to abiotic stresses. A wide number of transcriptional and posttranslational regulatory mechanisms of ABA signaling are known; however, less is known about the regulatory roles of alternative splicing. In this work, we found that SKIP, a splicing factor, positively regulates ABA signaling. SKIP binds to the pre-mRNA of ABA signaling-related genes, such as PYL7, PYL8, ABI1, HAB1 and ABI5, to regulate their splicing. The precursor mRNA alternative splicing of several PYL receptors, PP2C phosphatases and ABF transcriptional factors is disrupted by the skip-1 mutation. The abnormal alternative splicing in skip-1 represses the expression of ABA-positive regulators, including PYLs and ABFs, and activates the expression of ABA-negative regulators, such as PP2Cs, which confers ABA hyposensitive phenotype of skip-1. We also found that ABA-mediated genome-wide alternative splicing and differential gene expression are changed by the skip-1 mutation. The number of the differential splicing events is increased by skip-1; however, the number of differential expressed genes in response to ABA is reduced by skip-1. Our results reveal a principle on how a splicing factor regulates ABA signaling and ABA-mediated genome-wide alternative splicing.
脱落酸（ABA）在植物发育和对非生物胁迫的响应中起关键作用。已知ABA信号传导存在大量转录和翻译后调控机制；然而，关于可变剪接的调控作用却知之甚少。在这项研究中，我们发现剪接因子SKIP正向调控ABA信号传导。SKIP与ABA信号相关基因如PYL7、PYL8、ABI1、HAB1和ABI5的前体mRNA结合，以调控它们的剪接。skip-1突变破坏了几个PYL受体、PP2C磷酸酶和ABF转录因子的前体mRNA可变剪接。skip-1中异常的可变剪接抑制了包括PYLs和ABFs在内的ABA正向调节因子的表达，并激活了如PP2Cs等ABA负向调节因子的表达，这赋予了skip-1 ABA低敏感表型。我们还发现，skip-1突变改变了ABA介导的全基因组可变剪接和差异基因表达。skip-1增加了差异剪接事件的数量；然而, skip-1减少了响应ABA的差异表达基因的数量。我们的结果揭示了一个剪接因子如何调控ABA信号传导以及ABA介导的全基因组可变剪接的原理。
