PREMISE Interactions between fungal endophytes and their host plants present useful systems for identifying important factors affecting assembly of host-associated microbiomes. Here we investigated the role of secondary chemistry in mediating host affinity of asymptomatic foliar endophytic fungi using Psychotria spp. and Theobroma cacao (cacao) as hosts. METHODS First, we surveyed endophytic communities in Psychotria species in a natural common garden using culture-based methods. Then we compared differences in endophytic community composition with differences in foliar secondary chemistry in the same host species, determined by liquid chromatography-tandem mass spectrometry. Finally, we tested how inoculation with live and heat-killed endophytes affected the cacao chemical profile. RESULTS Despite sharing a common environment and source pool for endophyte spores, different Psychotria host species harbored strikingly different endophytic communities that reflected intrinsic differences in their leaf chemical profiles. In T. cacao, inoculation with live and heat-killed endophytes produced distinct cacao chemical profiles not found in uninoculated plants or pure fungal cultures, suggesting that endophytes, like pathogens, induce changes in secondary chemical profiles of their host plant. CONCLUSIONS Collectively our results suggest at least two potential processes: (1) Plant secondary chemistry influences assembly and composition of fungal endophytic communities, and (2) host colonization by endophytes subsequently induces changes in the host chemical landscape. We propose a series of testable predictions based on the possibility that reciprocal chemical interactions are a general property of plant-endophyte interactions.

中文翻译：

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内生真菌的宿主亲和力和涉及宿主二级化学的相互相互作用的潜力

前提真菌内生菌与其宿主植物之间的相互作用提供了有用的系统，可用于识别影响宿主相关微生物组组装的重要因素。在这里，我们使用 Psychotria spp 研究了二级化学在介导无症状叶面内生真菌宿主亲和力中的作用。和 Theobroma cacao (cacao) 作为宿主。方法首先，我们使用基于培养的方法调查了一个天然公共花园中的Psychotria 物种的内生群落。然后，我们通过液相色谱-串联质谱法比较了同一宿主物种内生群落组成的差异与叶次生化学的差异。最后，我们测试了接种活的和热灭活的内生菌如何影响可可化学特征。结果 尽管内生孢子共享一个共同的环境和来源库，但不同的 Psychotria 宿主物种拥有显着不同的内生群落，这反映了它们叶片化学特征的内在差异。在 T. cacao 中，接种活的和热灭活的内生菌产生了在未接种植物或纯真菌培养物中未发现的独特可可化学特征，这表明内生菌与病原体一样，会诱导宿主植物的次级化学特征发生变化。结论 总的来说，我们的结果表明至少有两个潜在的过程：（1）植物次生化学影响真菌内生群落的组装和组成，（2）内生菌的寄主定植随后引起寄主化学景观的变化。