Vainio Eeva J, Pennanen Taina, Rajala Tiina, Hantula Jarkko
FEMS Microbiol Ecol. 2017 Mar 1;93(3). doi: 10.1093/femsec/fix003.
Fungal viruses (mycoviruses) are considered to be highly host specific, but phylogenetic analysis supports the occasional occurrence of horizontal transmission between species. We used an extensive sampling strategy to investigate whether similar viruses occur in more than one fungal species of the same forest habitat. Mycelial samples were collected from in-growth mesh bags (N = 259), fruiting bodies (N = 173) and cultured isolates (N = 68) at a forest site where the spatial distribution of viral infections in clonal individuals of the wood decay fungus Heterobasidion parviporum was mapped in detail earlier. The investigation revealed previously known Heterobasidion viruses in ∼2% of the single or pooled mycorrhizal samples from mesh bags, ∼3% of the fruiting body samples and none of the fungal cultures analyzed. Novel virus strains distinct from known Heterobasidion viruses were detected in cultures of ectomycorrhizal fungi (Lactarius tabidus, L. rufus) and saprotrophic fungi (Megacollybia platyphylla, Mucoraceae spp.). Overall, our results support the view that mycoviruses do not readily cross species borders. Regarding potential virocontrol applications, the introduction of Heterobasidion viruses into natural habitats is not expected to cause a major infection pressure towards the indigenous fungal community. However, the ecological consequences of the putative interspecies virus transmission events detected require further investigation.
真菌病毒（真菌病毒）被认为具有高度的宿主特异性，但系统发育分析支持物种间偶尔发生水平传播。我们采用了广泛的采样策略，以调查同一森林栖息地的多种真菌物种中是否存在相似的病毒。在一个森林地点，从内生网袋（N = 259）、子实体（N = 173）和培养分离物（N = 68）中采集了菌丝体样本，此前已详细绘制了木材腐朽真菌小孢异担子菌克隆个体中病毒感染的空间分布。调查发现，在约2%的来自网袋的单个或混合菌根样本、约3%的子实体样本中检测到了先前已知的异担子菌病毒，而在分析的真菌培养物中均未检测到。在外生菌根真菌（松乳菇、红绒盖牛肝菌）和腐生真菌（阔叶大孔菌、毛霉科物种）的培养物中检测到了与已知异担子菌病毒不同的新型病毒株。总体而言，我们的结果支持真菌病毒不易跨越物种界限的观点。关于潜在的病毒防治应用，将异担子菌病毒引入自然栖息地预计不会对本地真菌群落造成重大感染压力。然而，检测到的假定种间病毒传播事件的生态后果需要进一步研究。
