Fungal endophytes for biocontrol of ash dieback: The antagonistic potential of Hypoxylon rubiginosum
Fungal endophytes for biocontrol of ash dieback: The antagonistic potential of Hypoxylon rubiginosum
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DOI：
10.1016/j.funeco.2020.100918
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发表时间：
2020-06-01
期刊：
影响因子：
2.9
通讯作者：
Schulz, Barbara
中科院分区：
文献类型：
--
作者：
Halecker, Sandra;Wennrich, Jan-Peer;Schulz, Barbara
我们的目标是开发一种生物控制剂，使用内生真菌来控制白蜡树枯梢病，这种疾病危及欧洲白蜡树的生存。这种保护性的内生菌应该产生对入侵真菌Hymenoscyphus fraxineus有毒的代谢产物，而Hymenoscyphus fraxineus是白蜡树枯梢病的病原体。从340株F. Excelsior，这里提供了与13个示例性分离物的相互作用。在H.内生真菌与病原菌之间几乎总是相互抑制的。抑制H.将抑制程度大于抑制程度的秦皮接种到无菌培养的Excelsior中，以选择在宿主中无症状生长的秦皮。大多数内生菌在无菌培养的F.的重要性，不仅要依靠共培养实验，但也在植物实验中使用。通过一个多位点的系谱结合形态学研究和比较与前表型文化，最有前途的菌株之一被确定为红褐团菌，子囊菌真菌，是密切相关的白蜡树，并经常产生其性变形的枯木的主机。使用制备HPLC，从H. fraxineus和H.通过核磁共振波谱和高分辨质谱鉴定了它们的结构。已知的植物毒素viridiol被检测为灰病原体在共培养中的主要代谢产物，先前已知的抗真菌代谢产物phomopsidin被检测为H.红褐色的此外，从H.红褐色的Phomopsidin是一种已知的β-微管蛋白抑制剂，靶向真核细胞骨架，抑制病原体，但也显示出轻微的细胞毒性作用。H. Rubiginosum在植物中无症状地生长，并且其产生抗真菌代谢物根霉糖苷，这使其有资格作为灰枯梢病的生物防治剂进一步开发的有希望的候选物。(C)2020 Elsevier Ltd和英国真菌学会。All rights reserved.
Our goal is to develop a biocontrol agent using endophytic fungi to control ash dieback, a disease that endangers the very existence of the European ash, Fraxinus excelsior. Such a protective endophyte should produce metabolites toxic to the invasive fungus Hymenoscyphus fraxineus, the causal agent of ash dieback. From a total of 340 fungal endophytes from F. excelsior, the interactions with 13 exemplary isolates are presented here. In co-culture between H. fraxineus and endophyte, there was almost always reciprocal inhibition between pathogen and endophyte. Endophytes that inhibited H. fraxineus more than they were inhibited by the pathogen were inoculated into axenically cultured E excelsior to select those that grew asymptomatically in the host. Most of the endophytes caused disease symptoms in axenically cultured F. excelsior seedlings, highlighting the importance of not only relying on co-culture experiments, but also using in planta experiments. By means of a multi-locus genealogy in conjunction with morphological studies and a comparison with the ex-epitype culture, one of the most promising isolates was identified as Hypoxylon rubiginosum, an ascomycete fungus that is closely associated with Fraxinus and frequently produces its sexual morph on dead wood of the host. Using preparative HPLC, metabolites were isolated from mono- and co-cultures of H. fraxineus and H. rubiginosum and their structures elucidated by NMR spectroscopy and HR mass spectrometry. The known phytotoxin viridiol was detected as a major metabolite of the ash pathogen in co-culture and the previously known antifungal metabolite, phomopsidin, as the major secondary metabolite of H. rubiginosum. In addition, the new metabolite, 10-hydroxyphomopsidin, was obtained from H. rubiginosum. Phomopsidin, a known inhibitor of beta-tubulin that targets the eukaryotic cytoskeleton, inhibited the pathogen, but also showed mild cytotoxic effects. The fact that H. rubiginosum grows asymptomatically in planta and that it produces the antifungal metabolite phomopsidin qualifies it as a promising candidate for further development as a biocontrol agent for ash dieback. (C) 2020 Elsevier Ltd and British Mycological Society. All rights reserved.