Ashrafi Samad, Wennrich Jan-Peer, Becker Yvonne, Maciá-Vicente Jose G, Brißke-Rode Anke, Daub Matthias, Thünen Torsten, Dababat Abdelfattah A, Finckh Maria R, Stadler Marc, Maier Wolfgang
Institute for Epidemiology and Pathogen Diagnostics, Julius Kühn Institute (JKI) - Federal Research Centre for Cultivated Plants, Messeweg 11/12, 38104, Brunswick, Germany.
Institute for Crop and Soil Science, Julius Kühn Institute (JKI) - Federal Research Centre for Cultivated Plants, Bundesallee 58, 38116, Brunswick, Germany.
IMA Fungus. 2023 Mar 30;14(1):6. doi: 10.1186/s43008-023-00113-w.
In this study fungal strains were investigated, which had been isolated from eggs of the cereal cyst nematode Heterodera filipjevi, and roots of Microthlaspi perfoliatum (Brassicaceae). The morphology, the interaction with nematodes and plants and the phylogenetic relationships of these strains originating from a broad geographic range covering Western Europe to Asia Minor were studied. Phylogenetic analyses using five genomic loci including ITSrDNA, LSUrDNA, SSUrDNA, rpb2 and tef1-α were carried out. The strains were found to represent a distinct phylogenetic lineage most closely related to Equiseticola and Ophiosphaerella, and Polydomus karssenii (Phaeosphaeriaceae, Pleosporales) is introduced here as a new species representing a monotypic genus. The pathogenicity tests against nematode eggs fulfilled Koch's postulates using in vitro nematode bioassays and showed that the fungus could parasitise its original nematode host H. filipjevi as well as the sugar beet cyst nematode H. schachtii, and colonise cysts and eggs of its hosts by forming highly melanised moniliform hyphae. Light microscopic observations on fungus-root interactions in an axenic system revealed the capacity of the same fungal strain to colonise the roots of wheat and produce melanised hyphae and microsclerotia-like structure typical for dark septate endophytes. Confocal laser scanning microscopy further demonstrated that the fungus colonised the root cells by predominant intercellular growth of hyphae, and frequent formation of appressorium-like as well as penetration peg-like structures through internal cell walls surrounded by callosic papilla-like structures. Different strains of the new fungus produced a nearly identical set of secondary metabolites with various biological activities including nematicidal effects irrespective of their origin from plants or nematodes.
在本研究中，对从禾谷孢囊线虫菲律宾异皮线虫的卵以及全缘叶微孔草（十字花科）的根中分离出的真菌菌株进行了研究。研究了这些来自西欧至小亚细亚广泛地理范围的菌株的形态、与线虫和植物的相互作用以及系统发育关系。使用包括ITS rDNA、LSU rDNA、SSU rDNA、rpb2和tef1-α在内的五个基因组位点进行了系统发育分析。这些菌株被发现代表了一个独特的系统发育谱系，与木贼座腔菌属和蛇孢壳属关系最为密切，并且在此引入了卡尔森多腔菌（多腔菌科，格孢腔菌目）作为代表单型属的新物种。使用体外线虫生物测定法对线虫卵进行的致病性测试符合科赫法则，结果表明该真菌能够寄生于其原始线虫宿主菲律宾异皮线虫以及甜菜孢囊线虫甜菜异皮线虫，并通过形成高度黑化的念珠状菌丝定殖于宿主的孢囊和卵中。在无菌系统中对真菌与根相互作用的光学显微镜观察揭示了同一真菌菌株定殖于小麦根并产生黑化菌丝和暗隔内生菌典型的微菌核状结构的能力。共聚焦激光扫描显微镜进一步证明，该真菌通过菌丝在细胞间的优势生长定殖于根细胞，并频繁形成类似附着胞以及穿透钉状结构，这些结构穿过由胼胝质乳头状结构包围的内部细胞壁。新真菌的不同菌株产生了一组几乎相同的具有各种生物活性（包括杀线虫作用）的次生代谢产物，无论它们源自植物还是线虫。
