玉米可变剪接调控的系统解析

Alternative splicing (AS) is prevalent in eukaryotes, which plays important roles in regulating gene expression and enhances proteome diversity. Therefore, identifying the genetic factors regulating AS variation will not only help us understand its roles in transcriptional and post-transcriptional regulation but also reveal its contribution to phenotypic variation. Although numerous studies on gene expression regulation by combining large-scale sequencing technologies and quantitative genetics have been reported in recent years, studying genetic variation regulating AS has received little attention in plants. Previously, we performed a genome-wide association study (GWAS) to identify genetic variants regulating AS variation, based on RNA-Seq data of immature maize kernels at 15 days after pollination from a natural population consisting of 368 diverse maize inbred lines. We dissected the genetic architecture of AS and investigated its regulatory mechanisms. We also explored the genetic relationship between AS and gene expression and its contribution to phenotypic variation. Furthermore, we identified a splicing factor ZmGRP1 which regulates the AS of numerous downstream genes. Based on these results, we will focus on the functional analysis of ZmGRP1 in this study, which will not only strengthen our understanding about the functional roles of trans-splicing factor in transcriptional and post-transcriptional regulation, but also provide novel insights of ZmGRP1 in regulating flowering time pathway in maize.

可变剪接在真核生物中广泛存在，是调节基因表达和产生蛋白质组多样性的重要机制。解析可变剪接变异的遗传调控机制不仅有助于理解转录和转录后调控，而且有助于评估可变剪接对表型变异的贡献。研究者利用高通量测序技术和数量遗传学手段对基因表达变异遗传调控机制开展了大量研究，但研究可变剪接变异的遗传调控机制在植物中还鲜有报道。本研究在前期对玉米未成熟籽粒的可变剪接变异进行全基因组关联分析，解析了可变剪接自然变异的遗传结构，探讨了可变剪接调控的分子机制，可变剪接与基因表达调控之间的关系，以及可变剪接对表型变异的贡献，此外还鉴定到了一个调控下游最多基因可变剪接变化的剪接因子ZmGRP1，并利用CRISP/Cas9技术进行了初步的验证。本研究将继续对ZmGRP1进行深入的功能研究，从而理解反式剪接因子在转录和转录后调控中的重要作用，同时明确ZmGRP1参与玉米开花途径的调控作用。

可变剪接在真核生物中广泛存在，是调节基因表达和产生蛋白质组多样性的重要机制。解析可变剪接变异的遗传调控机制不仅有助于理解转录和转录后调控，而且有助于评估可变剪接对表型变异的贡献。研究者利用高通量测序技术和数量遗传学手段对基因表达变异遗传调控机制开展了大量研究，但研究可变剪接变异的遗传调控机制在植物中还鲜有报道。本研究在前期对玉米未成熟籽粒的可变剪接变异进行全基因组关联分析，解析了可变剪接自然变异的遗传结构，探讨了可变剪接调控的分子机制，可变剪接与基因表达调控之间的关系，以及可变剪接对表型变异的贡献，此外还鉴定到了一个调控基因可变剪接变化的剪接因子ZmGRP1。本研究进一步分析了ZmGRP1的潜在功能，利用CRISPR/Cas9基因编辑技术对ZmGRP1进行基因敲除，研究ZmGRP1作为剪接因子在转录和转录后调控中的作用，研究ZmGRP1功能丧失后产生的农艺性状表型变化，着重关注其对玉米开花期的影响，同时利用候选基因关联分析挖掘ZmGRP1作为剪接因子调控下游基因可变剪接的功能位点。结果表明，ZmGRP1编码一个甘氨酸富集的RNA结合蛋白，主要定位在细胞核中，ZmGRP1功能丧失影响多个下游基因的可变剪接和基因表达水平变化，并导致植株延迟开花。本研究结果不仅对理解反式剪接因子在转录和转录后调控中的作用具有重要的参考价值，同时也给玉米现有的开花途径增加新的基因资源。