Grunewaldt-Stöcker Gisela, von Alten Henning
Institute of Horticultural Production Systems, Section Phytomedicine, Gottfried Wilhelm Leibniz Universität Hannover, Herrenhäuser Straße 2, 30419, Hannover, Germany.
Mycorrhiza. 2016 Jul;26(5):429-40. doi: 10.1007/s00572-016-0682-7. Epub 2016 Feb 5.
In previous investigations, we found that Acremonium strictum (strain DSM 100709) developed intracellular structures with similarity to mycelia of ericoid mycorrhizal fungi in the rhizodermal cells of flax plants and in hair roots of Rhododendron plantlets. A. strictum had also been isolated from roots of ericaceous salal plants and was described as an unusual ericoid mycorrhizal fungus (ERMF). As its mycorrhizal traits were doubted, we revised the hypothesis of a mycorrhizal nature of A. strictum. A successful synthesis of mycorrhiza in hair roots of inoculated ericaceous plants was a first step of evidence, followed by fluorescence microscopy with FUN(®)1 cell stain to observe the vitality of the host cells at the early infection stage. In inoculation trials with in vitro-raised mycorrhiza-free Rhododendron plants in axenic liquid culture and in greenhouse substrate culture, A. strictum was never observed in living hair root cells. As compared to the ERMF Oidiodendron maius and Rhizoscyphus ericae that invaded metabolically active host cells and established a symbiotic unit, A. strictum was only found in cells that were dead or in the process of dying and in the apoplast. In conclusion, A. strictum does not behave like a common ERMF-if it is one at all. A comparison of A. strictum isolates from ericaceous and non-ericaceous hosts could reveal further identity details to generalize or specify our findings on the symbiotic nature of A. strictum. At least, the staining method enables to discern between true mycorrhizal and other root endophytes-a tool for further studies.
在之前的研究中，我们发现，亚麻植株的根被细胞以及杜鹃幼苗的毛根中，细极链格孢（菌株DSM 100709）形成了与石楠类菌根真菌的菌丝体相似的细胞内结构。细极链格孢还从石楠科越橘属植物的根部分离得到，并被描述为一种不寻常的石楠类菌根真菌（ERMF）。由于其菌根特性受到质疑，我们修正了关于细极链格孢菌根性质的假说。接种石楠科植物的毛根中成功合成菌根是第一个证据，随后使用FUN(®)1细胞染料进行荧光显微镜观察，以观察早期感染阶段宿主细胞的活力。在无菌液体培养和温室基质培养中，对接种无菌根的体外培养杜鹃植株进行接种试验时，从未在活的毛根细胞中观察到细极链格孢。与侵入代谢活跃的宿主细胞并建立共生单元的ERMF大团囊菌和石楠盘菌相比，细极链格孢仅在死亡或即将死亡的细胞以及质外体中被发现。总之，细极链格孢的行为不像常见的ERMF——如果它根本算是ERMF的话。比较从石楠科和非石楠科宿主分离得到的细极链格孢菌株，可能会揭示更多的同一性细节，从而概括或明确我们关于细极链格孢共生性质的发现。至少，这种染色方法能够区分真正的菌根和其他根内生菌——这是进一步研究的一种工具。
