State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Taian, Shandong, 271018, China.
State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, Shandong, 271018, China.
New Phytol. 2023 Oct;240(2):644-662. doi: 10.1111/nph.19181. Epub 2023 Aug 2.
CircRNAs exist widely in plants, but the regulatory mechanisms for the biogenesis and function of plant circRNAs remain largely unknown. Using extensive mutagenesis of expression plasmids and genetic transformation methods, we analyzed the biogenesis and anti-salt functions of a new grape circRNA Vv-circSIZ1. We identified Vv-circSIZ1 that is mainly expressed in the cytoplasm of xylem. CircSIZ1 is species-specific, and genomic circSIZ1-forming region of seven tested species could be backspliced in Nicotiana benthamiana, but not in Arabidopsis. The retention length of Vv-circSIZ1 flanking introns was significantly positively correlated with its generation efficiency. The precise splicing of Vv-circSIZ1 does not depend on its mature exon sequence or internal intron sequences, but on the AG/GT splicing signal sites and branch site of the flanking introns. The spliceosome activity was inversely proportional to the expression level of Vv-circSIZ1. Furthermore, RNA-binding proteins can regulate the expression of Vv-circSIZ1. The overexpression of Vv-circSIZ1 improved salt tolerance of grape and N. benthamiana. Additionally, Vv-circSIZ1 could relieve the repressive effect of VvmiR3631 on its target VvVHAc1. Vv-circSIZ1 also promoted transcription of its parental gene. Overall, these results broaden our understanding of circRNAs in plants.
circRNAs 广泛存在于植物中，但植物 circRNAs 的生物发生和功能的调控机制在很大程度上仍然未知。我们使用表达质粒的广泛诱变和遗传转化方法，分析了一种新的葡萄 circRNA Vv-circSIZ1 的生物发生和抗盐功能。我们鉴定了主要在木质部细胞质中表达的 Vv-circSIZ1。CircSIZ1 是种特异性的，在七种测试物种的基因组 circSIZ1 形成区域可以在本氏烟中反向剪接，但不能在拟南芥中。Vv-circSIZ1 侧翼内含子的保留长度与其产生效率呈显著正相关。Vv-circSIZ1 的精确剪接不依赖于其成熟外显子序列或内部内含子序列，而是依赖于侧翼内含子的 AG/GT 剪接信号位点和分支位点。剪接体活性与 Vv-circSIZ1 的表达水平成反比。此外，RNA 结合蛋白可以调节 Vv-circSIZ1 的表达。Vv-circSIZ1 的过表达提高了葡萄和本氏烟的耐盐性。此外，Vv-circSIZ1 可以缓解 VvmiR3631 对其靶基因 VvVHAc1 的抑制作用。Vv-circSIZ1 还促进了其亲本基因的转录。总的来说，这些结果拓宽了我们对植物中 circRNAs 的认识。
