Soil microbial communities are often subject to the influence of plants ( Bardgett and Van Der Putten, 2014). Microbial communities from the soil surrounding the roots (rhizosphere), for example, can reflect a host of conditions shaped by plants including temperature, pH, salinity, nutrient availability, and organic matter (Lozupone and Knight, 2007;Sharp et al., 2014). These and similar relationships raise the possibility of functional linkages between rhizosphere microbial community composition and trait variation

Leaf-cutting ants encounter many fungi in their environment that may occur as parasites, entomopathogens, saprotrophs, or neutral/beneficial symbionts. The source of these microfungi may be the surrounding soil or the plant material brought to the nest by the ants. Whether the ants' hygienic behavior toward these microfungi is generalized or specific to different fungal species is unknown. We isolated microfungi from leaf-cutting ant gardens and forage material, and then tested the response of the worker ants to these fungal cultures. We found large variation in the rate that ants removed microfungi from their garden chamber. Some strains, including strains of the genera Trichoderma, Escovopsis and Xylaria, were removed at higher rates than others. Our data suggest that the worker ants moderate their behavior in a species-specific rather than generalized fashion when responding to different types of microfungi. Index descriptors: Leaf-cutting ants, endophytes, symbiosis, pathogens, Xylaria Introduction: Leaf-cutting ants (tribe: Attini) have domesticated the fungus Leucoagaricus gongylophorus (Basidiomycota: Agaricales: Agaricaceae) that they tend as a monoculture garden in underground chambers, superficial gardens, or within natural shelters such as rotten logs (Mueller et al., 2010; Sosa-Calvo et al., 2015). Fungiculture practiced by the genus Atta involves the decomposition of fresh plant substratum, which is harvested, processed and planted in a fungal garden by the ants. The fungal garden provides a reliable nutrition source, particularly for the ant larvae, and is high in proteins and carbohydrates (Quinlan and Cherrett, 1979). Leafcutting ants in the tropics encounter a diverse range of fungi through their natural history. Fungi are present in the soil, on and within the plant tissue they cut, and in the air as spores (Rodrigues et al., 2008; Van Bael et al., 2009). The monoculture garden fungus is subject to disease caused

While the endosymbiotic communities recruited by plants are known to vary among host species and across environmental gradients, the drivers of community assembly remain poorly understood. We tested the hypothesis that establishment of an endosymbiotic bacterial community is driven primarily by the influence of the abiotic environment on biotic interactions between plant and soil bacteria. We planted sterile Jatropha curcas seedlings at three field sites in Panama and in a greenhouse with soil from those sites. After allowing sufficient time for endosymbiont colonization, we sequenced bacterial 16S rRNA to study the endophytic bacterial community in root and leaf tissue. We compared the communities between field and greenhouse plants and examined associations among the endosymbionts, the soil microbial community, and local abiotic factors. We found that endosymbiont richness and community composition varied between the greenhouse and field, despite plants being grown in the same soil. Plants in each field site harbored a distinct bacterial community, determined by soil microbes and select environmental variables, particularly major plant nutrients. Jatropha curcas can harbor a wide variety of endosymbiotic communities, and the composition of these communities is a product of the local environment. Fertility and agricultural practices may determine the fate of plant symbionts and therefore plant properties modulated through those symbionts.

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