College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China.
Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA.
Environ Microbiol. 2021 Sep;23(9):5052-5068. doi: 10.1111/1462-2920.15446. Epub 2021 Mar 9.
In wheat head blight fungus Fusarium graminearum, A-to-I RNA editing occurs specifically during sexual reproduction. Among the genes with premature stop codons (PSCs) that require RNA editing to encode full-length proteins, FgBUD14 also had alternative splicing events in perithecia. In this study, we characterized the functions of FgBUD14 and its post-transcriptional modifications during sexual reproduction. The Fgbud14 deletion mutant was slightly reduced in growth, conidiation and virulence. Although deletion of FgBUD14 had no effect on perithecium morphology, the Fgbud14 mutant was defective in crozier formation and ascus development. The FgBud14-GFP localized to the apex of ascogenous hyphae and croziers, which may be related to its functions during early sexual development. During vegetative growth and asexual reproduction, FgBud14-GFP localized to hyphal tips and both ends of conidia. Furthermore, mutations blocking the splicing of intron 2 that has the PSC site had no effect on the function of FgBUD14 during sexual reproduction but caused a similar defect in growth with Fgbud14 mutant. Expression of the non-editable FgBUD14 mutant allele also failed to complement the Fgbud14 mutant. Taken together, FgBUD14 plays important roles in ascus development, and both alternative splicing and RNA editing occur specifically to its transcripts during sexual reproduction in F. graminearum.
在小麦赤霉病菌 Fusarium graminearum 中，A-to-I RNA 编辑特异性地发生在有性生殖过程中。在需要 RNA 编辑才能编码全长蛋白的具有提前终止密码子（PSC）的基因中，FgBUD14 在子囊壳中也存在选择性剪接事件。在本研究中，我们对 FgBUD14 的功能及其在有性生殖过程中的转录后修饰进行了表征。Fgbud14 缺失突变体在生长、产孢和毒力方面略有降低。尽管删除 FgBUD14 对子囊壳形态没有影响，但 Fgbud14 突变体在小梗形成和子囊发育方面存在缺陷。FgBud14-GFP 定位于产囊菌丝和小梗的顶端，这可能与其在早期有性发育过程中的功能有关。在营养生长和无性繁殖过程中，FgBud14-GFP 定位于菌丝尖端和分生孢子的两端。此外，阻断具有 PSC 位点的内含子 2 剪接的突变对 FgBUD14 在有性生殖过程中的功能没有影响，但与 Fgbud14 突变体的生长缺陷相似。非编辑 FgBUD14 突变等位基因的表达也未能互补 Fgbud14 突变体。总之，FgBUD14 在子囊发育中发挥重要作用，并且在 F. graminearum 的有性生殖过程中，其转录物特异性地发生选择性剪接和 RNA 编辑。
