Department of Plant Pathology and Plant-Microbe Biology, Cornell University 334 Plant Science Building, Ithaca, New York, 14853-4203.
Ecol Evol. 2013 Dec;3(16):5254-67. doi: 10.1002/ece3.900. Epub 2013 Dec 3.
Soil pathogens are believed to be major contributors to negative plant-soil feedbacks that regulate plant community dynamics and plant invasions. While the theoretical basis for pathogen regulation of plant communities is well established within the plant-soil feedback framework, direct experimental evidence for pathogen community responses to plants has been limited, often relying largely on indirect evidence based on above-ground plant responses. As a result, specific soil pathogen responses accompanying above-ground plant community dynamics are largely unknown. Here, we examine the oomycete pathogens in soils conditioned by established populations of native noninvasive and non-native invasive haplotypes of Phragmites australis (European common reed). Our aim was to assess whether populations of invasive plants harbor unique communities of pathogens that differ from those associated with noninvasive populations and whether the distribution of taxa within these communities may help to explain invasive success. We compared the composition and abundance of pathogenic and saprobic oomycete species over a 2-year period. Despite a diversity of oomycete taxa detected in soils from both native and non-native populations, pathogen communities from both invaded and noninvaded soils were dominated by species of Pythium. Pathogen species that contributed the most to the differences observed between invaded and noninvaded soils were distributed between invaded and noninvaded soils. However, the specific taxa in invaded soils responsible for community differences were distinct from those in noninvaded soils that contributed to community differences. Our results indicate that, despite the phylogenetic relatedness of native and non-native P. australis haplotypes, pathogen communities associated with the dominant non-native haplotype are distinct from those of the rare native haplotype. Pathogen taxa that dominate either noninvaded or invaded soils suggest different potential mechanisms of invasion facilitation. These findings are consistent with the hypothesis that non-native plant species that dominate landscapes may "cultivate" a different soil pathogen community to their rhizosphere than those of rarer native species.
土壤病原体被认为是负向植物-土壤反馈的主要贡献者，这些反馈调节植物群落动态和植物入侵。虽然病原体对植物群落的调节在植物-土壤反馈框架中具有很好的理论基础，但对病原体群落对植物的直接实验证据一直很有限，通常主要依赖于基于地上植物响应的间接证据。因此，伴随着地上植物群落动态的具体土壤病原体响应在很大程度上是未知的。在这里，我们研究了在建立的本地非入侵和非本地入侵的芦苇（欧洲普通芦苇）种群条件下的卵菌病原体。我们的目的是评估入侵植物种群是否拥有与非入侵种群相关的独特病原体群落，以及这些群落中分类群的分布是否有助于解释入侵成功。我们在两年的时间里比较了致病性和腐生性卵菌物种的组成和丰度。尽管在本地和非本地种群的土壤中都检测到了多种卵菌类群，但来自入侵和非入侵土壤的病原体群落都以节旋菌属物种为主。对观察到的入侵和非入侵土壤之间差异贡献最大的病原体物种分布在入侵和非入侵土壤之间。然而，导致入侵土壤群落差异的特定分类群与导致非入侵土壤群落差异的分类群不同。我们的研究结果表明，尽管本地和非本地芦苇单倍型具有系统发育上的亲缘关系，但与占优势的非本地单倍型相关的病原体群落与稀有本地单倍型的病原体群落不同。主导非入侵或入侵土壤的病原体分类群表明了不同的入侵促进潜在机制。这些发现与以下假设一致，即占主导地位的非本地植物物种可能会“培育”与其根际不同的土壤病原体群落，而不是那些稀有本地物种。
