Botanical Institute, Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, 50674, Cologne, Germany.
Department of Cell and Metabolic Biology, Institute of Plant Biochemistry, 06120, Halle (Saale), Germany.
New Phytol. 2019 Oct;224(2):886-901. doi: 10.1111/nph.15904. Epub 2019 Jun 25.
In nature, beneficial and pathogenic fungi often simultaneously colonise plants. Despite substantial efforts to understand the composition of natural plant-microbe communities, the mechanisms driving such multipartite interactions remain largely unknown. Here we address how the interaction between the beneficial root endophyte Serendipita vermifera and the pathogen Bipolaris sorokiniana affects fungal behaviour and determines barley host responses using a gnotobiotic soil-based split-root system. Fungal confrontation in soil resulted in induction of B. sorokiniana genes involved in secondary metabolism and a significant repression of genes encoding putative effectors. In S. vermifera, genes encoding hydrolytic enzymes were strongly induced. This antagonistic response was not activated during the tripartite interaction in barley roots. Instead, we observed a specific induction of S. vermifera genes involved in detoxification and redox homeostasis. Pathogen infection but not endophyte colonisation resulted in substantial host transcriptional reprogramming and activation of defence. In the presence of S. vermifera, pathogen infection and disease symptoms were significantly reduced despite no marked alterations of the plant transcriptional response. The activation of stress response genes and concomitant repression of putative effector gene expression in B. sorokiniana during confrontation with the endophyte suggest a reduction of the pathogen's virulence potential before host plant infection.
在自然界中，有益真菌和致病真菌经常同时定殖于植物上。尽管人们为了了解自然植物-微生物群落的组成付出了巨大努力，但这些多组分相互作用的机制在很大程度上仍然未知。在这里，我们使用基于土壤的根分区系统，研究了有益根内生真菌串珠镰孢菌（Serendipita vermifera）与病原菌旋孢腔菌（Bipolaris sorokiniana）之间的相互作用如何影响真菌行为并决定大麦宿主的反应。在土壤中进行的真菌对抗导致 B. sorokiniana 参与次生代谢的基因被诱导，而编码假定效应子的基因则受到显著抑制。在 S. vermifera 中，水解酶基因强烈诱导。在大麦根系的三方相互作用中，没有激活这种拮抗反应。相反，我们观察到 S. vermifera 参与解毒和氧化还原稳态的基因被特异性诱导。病原菌感染而不是内生菌定殖导致宿主转录组发生显著重编程并激活防御。尽管植物转录反应没有明显改变，但内生菌的存在使病原菌感染和疾病症状显著减少。在与内生菌对抗时，病原菌旋孢腔菌中应激反应基因的激活和假定效应子基因表达的同时抑制表明，在感染宿主植物之前，病原菌的毒力潜力降低。
