Wetland plant evolutionary history influences soil and endophyte microbial community composition

Methane is a microbially derived greenhouse gas whose emissions are highly variable throughout wetland ecosystems. Differences in plant community composition account for some of this variability, suggesting an influence of plant species on microbial community structure and function in these ecosystems. Given that closely related plant species have similar morphological and biochemical features, we hypothesize that plant evolutionary history is related to differences in microbial community composition. To examine species-specific patterns in microbiomes, we selected five monoculture-forming wetland plant species based on the evolutionary distances among them. We detected significant differences in microbial communities between sample types (unvegetated soil, bulk soil, rhizosphere soil, internal root tissues, and internal leaf tissues) associated with these plant species based on 16S relative abundances. We additionally found that differences in plant evolutionary history were correlated with variation in microbial communities across plant species within each sample type. Using qPCR, we observed substantial differences in overall methanogen and methanotroph population sizes between plant species and sample types. Methanogens tended to be most abundant in rhizosphere soils while methanotrophs were the most abundant in roots. Given that microbes influence methane flux and that plants affect methanogen and methanotroph populations, plant species contribute to variable degrees of methane emissions. Incorporating the influence of plant evolutionary history into future modeling efforts may improve predictions of wetland methane emission since microbial community differences correlate with differences in plant evolutionary history.