Microbial symbionts are gaining attention as crucial drivers of invasive species spread and dominance. To date, much research has quantified the net effects of plant–microbe interactions on the relative success of native and invasive species. However, little is known about how the structure (composition and diversity) of microbial symbionts can differ among native and invasive species, or vary across the invasive landscape. Here, we explore the structure of endosphere and soil fungal communities associated with a monoculture-forming widespread invader, Phragmites australis, and co-occurring native species. Using field survey data from marshes in coastal Louisiana, we tested three hypotheses: (1) Phragmites australis root and soil fungal communities differ from that of co-occurring natives, (2) Phragmites australis monocultures harbor distinct fungal communities at the expanding edge compared to the monodominant center, and (3) proximity to the P. australis invading front alters native root endosphere and soil fungal community structure. We found that P. australis cultivates root and soil fungal communities with higher richness, diversity, and pathogen abundances compared to native species. While P. australis was found to have higher endosphere pathogen abundances at its expanding edge compared to the monodominant center, we found no evidence of compositional changes or pathogen spillover in native species in close proximity to the invasion front. This work suggests that field measurements of fungal endosphere communities in native and invasive plants are useful to help understand (or rule out) mechanisms of invasion.

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芦苇与具有高度多样性和病原体丰富性的地下真菌群落相关

作为入侵物种扩散和主导地位的重要驱动力，微生物共生体越来越受到关注。迄今为止，许多研究已经量化了植物与微生物相互作用对本地物种和入侵物种相对成功的净影响。但是，关于微生物共生体的结构（组成和多样性）如何在自然物种和入侵物种之间不同或在整个入侵环境中变化的知之甚少。在这里，我们探索与形成单一文化的广泛入侵者，芦苇和共同存在的本地物种相关的内球和土壤真菌群落的结构。使用路易斯安那州沿海沼泽地的实地调查数据，我们检验了三个假设：（1）芦苇根真菌和土壤真菌群落不同于同时存在的原生真菌群落；（2）芦苇单一菌种在扩张边缘与单一优势中心相比，具有独特的真菌群落，（3）接近入侵的澳大利亚假单胞菌改变了原生根内球面和土壤真菌群落结构。我们发现，与本地物种相比，澳大利亚假单胞菌培育的根和土壤真菌群落具有更高的丰富性，多样性和病原体丰富度。虽然芦苇与单一优势中心相比，我们发现在扩张边缘具有更高的内层病原体丰富度，我们没有发现入侵前沿附近的本地物种的成分变化或病原体溢出的证据。这项工作表明，对原生植物和入侵植物中真菌内球体群落的野外测量有助于了解（或排除）入侵机制。