Division of Biology, Kansas State University, Manhattan, Kansas 66506, USA.
Mycologia. 2010 Jul-Aug;102(4):813-21. doi: 10.3852/09-212.
Dark septate endophytes (DSE) are common and abundant root-colonizing fungi in the native tallgrass prairie. To characterize DSE fungi were isolated from roots of mixed tallgrass prairie plant communities. Isolates were grouped according to morphology, and the grouping was refined by ITS-RFLP and/or sequencing of the ITS region. Sporulating species of Periconia, Fusarium, Microdochium and Aspergillus were isolated along with many sterile fungi. Leek resynthesis was used to quickly screen for DSE fungi among the isolates. Periconia macro-spinosa and Microdochium sp. formed typical DSE structures in the roots; Periconia produced melanized intracellular microsclerotia in host root cortex, whereas Microdochium produced abundant melanized inter- and intracellular chlamydospores. To further validate the results of the leek resynthesis growth responses of leek and a dominant prairie grass, Andropogon gerardii, were assessed in a laboratory resynthesis system. Leek growth mainly was unresponsive to the inoculation with Periconia or Microdochium, whereas Andropogon tended to respond positively. Select Periconia and Microdochium isolates were tested further for their enzymatic capabilities and for ability to use organic and inorganic nitrogen sources. These fungi tested positive for amylase, cellulase, polyphenol oxidases and gelatinase. Periconia isolates used both organic and inorganic nitrogen sources. Our study identified distinct endophytes in a tallgrass prairie ecosystem and indicated that these endo-phytes can use a variety of complex nutrient sources, suggesting facultative biotrophic and saprotrophic habits.
深色隔孢腔真菌（DSE）是原生高草草原中常见且丰富的根系定殖真菌。为了描述 DSE 真菌，我们从混合高草草原植物群落的根系中分离出真菌。根据形态将分离物分组，然后通过 ITS-RFLP 和/或 ITS 区测序对分组进行细化。分离出的 Periconia、Fusarium、Microdochium 和 Aspergillus 等有孢子形成的种，以及许多无菌真菌。使用韭菜再合成法快速筛选分离物中的 DSE 真菌。Periconia macro-spinosa 和 Microdochium sp. 在根系中形成典型的 DSE 结构；Periconia 在宿主根皮层中产生黑褐色细胞内小体，而 Microdochium 则产生丰富的黑褐色细胞内外厚垣孢子。为了进一步验证韭菜再合成生长反应的结果，我们在实验室再合成系统中评估了韭菜和优势草原草 Andropogon gerardii 的生长反应。韭菜的生长主要对 Periconia 或 Microdochium 的接种没有反应，而 Andropogon 则倾向于积极响应。进一步选择 Periconia 和 Microdochium 分离物，测试其酶活性和利用有机和无机氮源的能力。这些真菌对淀粉酶、纤维素酶、多酚氧化酶和明胶酶呈阳性反应。Periconia 分离物同时利用有机和无机氮源。我们的研究在高草草原生态系统中鉴定出了独特的内生真菌，并表明这些内生真菌可以利用多种复杂的营养源，这表明它们具有兼性生物营养和腐生习性。
