Biological invasions have significant impacts on ecosystems across the Earth, such that the mechanisms driving invasions have been widely studied. Recent studies have focused on the plant-associated microbiome, because it could provide a mechanism for colonization and recruitment of invaders, as well as for decreased performance of native species. By cultivating their own microbial community, invasive plants could plausibly dominate a community through escape from the pathogens of their native range coupled with unfettered interactions with mutualists. Therefore, the relative abundances and identity of mutualists and pathogens is extremely important for invader success.
We conducted a survey to understand how the native and non-native lineages of Phragmites australis differed in their fungal symbionts, and how those communities were affected by soil nutrients. We collected root samples from populations of both lineages at seven sites across Michigan, USA that differed with respect to nutrient availability. Root tissues were surface sterilized and freeze dried, followed by genomic DNA extraction. The internal transcribed spacer (ITS) of rDNA was amplified using the fungal primers ITS1F and ITS4 and sequenced to identify the fungal taxa in roots. Roots of each lineage were also stained and examined for fungal hyphae presence using microscopy.
Results/Conclusions
Hyphal counts indicated that hyphal colonization was higher among the non-native (18 ± 3%) lineage than the native (7 ± 1%) lineage across all sites (P < 0.0001). Site was also a significant predictor of variation (P = 0.0005). Neither total nitrogen nor total phosphorus were significant predictors of colonization across all sites and both lineages. Community analysis from amplified DNA revealed differences in root fungal communities between lineages. Results indicate that non-native Phragmites had higher root colonization than native Phragmites, which appears to be associated with leaf tissue nutrient status. Analysis of functional group assignments for OTU’s is ongoing. If the balance between mutualistic and pathogenic fungi differs between the native and non-native lineages, performance differences may be explained partially by microbially-mediated plant-soil feedbacks.