Abstract

Signaling by the phytohormone abscisic acid (ABA) involves pre-mRNA splicing, a key process of post-transcriptional regulation of gene expression. However, the regulatory mechanism of alternative pre-mRNA splicing in ABA signaling remains largely unknown. We previously identified a pentatricopeptide repeat protein SOAR1 (suppressor of the ABAR-overexpressor 1) as a crucial player downstream of ABAR (putative ABA receptor) in ABA signaling. In this study, we identified a SOAR1 interaction partner USB1, which is an exoribonuclease catalyzing U6 production for spliceosome assembly. We reveal that together USB1 and SOAR1 negatively regulate ABA signaling in early seedling development. USB1 and SOAR1 are both required for the splicing of transcripts of numerous genes, including those involved in ABA signaling pathways, suggesting that USB1 and SOAR1 collaborate to regulate ABA signaling by affecting spliceosome assembly. These findings provide important new insights into the mechanistic control of alternative pre-mRNA splicing in the regulation of ABA-mediated plant responses to environmental cues.

中文翻译：

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拟南芥外切核糖核酸酶USB1与PPR域蛋白SOAR1相互作用，以负面调节脱落酸信号传导。

摘要

植物激素脱落酸（ABA）发出的信号涉及前mRNA剪接，这是转录后调节基因表达的关键过程。然而，在ABA信号转导中，选择性的pre-mRNA剪接的调控机制仍然未知。我们先前确定了五肽重复蛋白SOAR1（ABAR过表达子1的抑制子）是ABA信号下游ABAR（假定的ABA受体）下游的重要角色。在这项研究中，我们确定了SOAR1相互作用伴侣USB1，它是一种外切核酸酶，催化U6产生，用于剪接体组装。我们揭示USB1和SOAR1一起在早期幼苗发育中负调控ABA信号传导。USB1和SOAR1都是许多基因的转录物剪接所必需的，包括与ABA信号通路有关的基因，提示USB1和SOAR1通过影响剪接体装配来协同调节ABA信号传导。这些发现为替代前体mRNA剪接的机械控制在调控ABA介导的植物对环境线索的反应中提供了重要的新见解。