Swiss Federal Research Institute WSL, Forest Dynamics, Zuercherstrasse 111, 8903 Birmensdorf, Switzerland.
INRA, UMR INRA-Université de Lorraine 'Interactions Arbres/Microorganismes', Laboratoire d'Excellence ARBRE, INRA-Nancy, 54280 Champenoux, France.
Nat Commun. 2016 Sep 7;7:12662. doi: 10.1038/ncomms12662.
The most frequently encountered symbiont on tree roots is the ascomycete Cenococcum geophilum, the only mycorrhizal species within the largest fungal class Dothideomycetes, a class known for devastating plant pathogens. Here we show that the symbiotic genomic idiosyncrasies of ectomycorrhizal basidiomycetes are also present in C. geophilum with symbiosis-induced, taxon-specific genes of unknown function and reduced numbers of plant cell wall-degrading enzymes. C. geophilum still holds a significant set of genes in categories known to be involved in pathogenesis and shows an increased genome size due to transposable elements proliferation. Transcript profiling revealed a striking upregulation of membrane transporters, including aquaporin water channels and sugar transporters, and mycorrhiza-induced small secreted proteins (MiSSPs) in ectomycorrhiza compared with free-living mycelium. The frequency with which this symbiont is found on tree roots and its possible role in water and nutrient transport in symbiosis calls for further studies on mechanisms of host and environmental adaptation.
最常出现在树根上的共生体是子囊菌门的地衣芽孢杆菌，这是最大的真菌门子囊菌门中唯一的菌根真菌，该门以破坏性植物病原体而闻名。在这里，我们表明，外生菌根担子菌的共生基因组特征也存在于地衣芽孢杆菌中，具有共生诱导的、具有未知功能的分类特异性基因和减少的植物细胞壁降解酶数量。地衣芽孢杆菌仍然拥有大量与致病性相关的基因，并且由于转座元件的增殖而导致基因组大小增加。转录谱分析显示，与自由生活的菌丝体相比，外生菌根中膜转运蛋白（包括水通道和糖转运蛋白）和菌根诱导的小分泌蛋白（MiSSPs）的表达显著上调。这种共生体在树根上的出现频率及其在共生体中运输水和养分的可能作用，需要进一步研究宿主和环境适应的机制。
