Invasive genotypes of Phragmites australis have distinct active microbial communities in the rhizosphere compared to native genotypes

Background/Question/Methods

Multiple lineages of Phragmites australis (common reed), including a dominant introduced invasive lineage and a non-invasive native lineage, colonize inland and coastal wetlands in North America. The role that these genotypic variations play in the invasion success of introduced Phragmites is not well understood. In particular, the question remains whether population level differences in the plant community have cascading effects on the microbes that inhabit the rhizosphere and whether such changes alter plant chemistry and fitness.  To address these questions, we performed a common garden experiment where we grew 15 different native and invasive genotypes of P. australis under greenhouse conditions in a homogenized soil mixture for four months. After four months we extracted DNA and RNA from the rhizosphere soil and we sequenced the 16S rRNA and 16S rDNA to assess both the active (16S rRNA) and total (16S rDNA) microbial communities. We also measured above and belowground biomass, total phenolics, and plant carbon and nitrogen.

Results/Conclusions

The structure of the total microbial community did not show a clear divergence among genotypes. When examining only the active portion of the microbial community, however, the data indicated that the invasive variants of P. australis all have repeatable and distinct microbial community structures in their rhizosphere soils while the native variants all had highly similar microbial community structures.  These data suggest that introduced P. australis genotypes impart a stronger signal on the rhizosphere soil microbial community than do their native counterparts, which may facilitate invasion success and have positive effects on plant traits of the invader.