Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN 55108, U.S.A.
USDA ARS Cereal Disease Laboratory, St. Paul, MN 55108, U.S.A.
Mol Plant Microbe Interact. 2020 Jul;33(7):888-901. doi: 10.1094/MPMI-01-20-0012-R. Epub 2020 Jun 1.
The plant-pathogenic fungus , causal agent of Fusarium head blight (FHB) disease on small grain cereals, produces toxic trichothecenes that require facilitated export for full virulence. Two potential modes of mycotoxin transport are membrane-bound transporters, which move toxins across cellular membranes, and -ethylmaleimide-sensitive factor attachment receptor (SNARE)-mediated vesicular transport, by which toxins may be packaged as cargo in vesicles bound for organelles or the plasma membrane. In this study, we show that deletion of a gene () for a subapically localized t-SNARE protein results in growth alteration, increased sensitivity to xenobiotics, altered gene expression profiles, and reduced deoxynivalenol (DON) accumulation in vitro and in planta as well as reduced FHB symptoms on wheat. A double deletion mutant generated by crossing the deletion mutant with an ATP-binding cassette transporter deletion mutant () resulted in an additive reduction in DON accumulation and almost complete loss of FHB symptoms in planta. These results suggest an important role of Sso2-mediated subapical exocytosis in FHB progression and xenobiotic defense and are the first report of an additive reduction in DON accumulation upon deletion of two distinct modes of cellular export. This research provides useful information which may aid in formulating novel management plans of FHB or other destructive plant diseases.
植物病原真菌是导致小谷物赤霉病（FHB）的病原体，它会产生有毒的三萜烯，需要促进其外排才能充分发挥毒性。真菌毒素运输有两种潜在方式：一种是通过膜结合转运蛋白，将毒素穿过细胞膜进行运输；另一种是通过 -乙基马来酰亚胺敏感因子附着受体（SNARE）介导的囊泡运输，通过这种方式，毒素可以作为囊泡中的货物被包裹起来，运往细胞器或质膜。在这项研究中，我们表明，缺失一个定位于亚顶区的 t-SNARE 蛋白基因（）会导致生长改变、对外源化学物质的敏感性增加、基因表达谱改变，以及在体外和体内赤霉烯酮（DON）积累减少，同时小麦赤霉病症状减轻。通过将 缺失突变体与一个 ATP 结合盒转运蛋白缺失突变体（）杂交产生的双缺失突变体，导致 DON 积累进一步减少，体内赤霉病症状几乎完全消失。这些结果表明 Sso2 介导的亚顶区胞吐作用在赤霉病进展和对外源化学物质的防御中起着重要作用，这也是首次报道通过删除两种不同的细胞外排方式，DON 积累会出现累加减少。这项研究提供了有用的信息，可能有助于制定赤霉病或其他破坏性植物病害的新管理计划。
