Military training can create disturbances that facilitate invasive plant establishment. Introduced plant species interactions with soil microbial communities through root exudates often aid plants in colonizing new locales. This study tested the hypothesis that rhizosphere bacterial communities associated with the native legume, Lespedeza virginica, and the non-native legume, Lespedeza cuneata, respond differently to plant-exuded molecules. Bacterial communities collected from coexisting populations of the two plant species were grown in the presence of four separate flavonoids at four concentrations. Following 96 hours of incubation, DNA was recovered from the enrichment cultures and analyzed using next-generation sequencing. In cultures receiving a flavonoid, L. virginica enrichments were characterized by a greater OTU richness and exhibited a dose-response relationship to one of the flavonoids. The L. cuneata enrichments were characterized by a decreased OTU richness. Bacterial genera containing known pathogenic taxa occurred at a significantly greater relative frequency in L. cuneata enrichments than in the L. virginica enrichments. However, calculation of a species diversity index indicated greater OTU diversity in the L. cuneata enrichments across all four flavonoid treatments. These results indicate that the rhizosphere microbial communities of co-existing L. cuneata and L. virginica legumes exhibit different responses when exposed to plant communication molecules.
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