Home-field advantage affects the local adaptive interaction betweenAndropogon gerardiiecotypes and root-associated bacterial communities

Abstract

Due to climate change, drought frequencies and severities are predicted to increase across the United States. Plant responses and adaptation to stresses depend on plant genetic and environmental factors. Understanding the effect of those factors on plant performance is required to predict species’ responses to environmental change. We used reciprocal gardens planted with distinct regional ecotypes of the perennial grass Andropogon gerardii adapted to dry, mesic, and wet environments to characterize their rhizosphere communities using 16S rRNA metabarcode sequencing. Even though the local microbial pool was the main driver of these rhizosphere communities, the significant plant ecotypic effect highlighted active microbial recruitment in the rhizosphere, driven by ecotype or plant genetic background. Our data also suggest that ecotypes planted at their homesites were more successful in recruiting rhizosphere community members that were unique to the location. The link between the plants’ homesite and the specific local microbes supported the “home field advantage” hypothesis. The unique homesite microbes may represent microbial specialists that are linked to plant stress responses. Furthermore, our data support ecotypic variation in the recruitment of congeneric but distinct bacterial variants, highlighting the nuanced plant ecotype effects on rhizosphere microbiome recruitment. These results improve our understanding of the complex plant host–soil microbe interactions and should facilitate further studies focused on exploring the functional potential of recruited microbes. Our study has the potential to aid in predicting grassland ecosystem responses to climate change and impact restoration management practices to promote grassland sustainability. IMPORTANCE In this study, we used reciprocal gardens located across a steep precipitation gradient to characterize rhizosphere communities of distinct dry, mesic, and wet regional ecotypes of the perennial grass Andropogon gerardii . We used 16S rRNA amplicon sequencing and focused oligotyping analysis and showed that even though location was the main driver of the microbial communities, ecotypes could potentially recruit distinct bacterial populations. We showed that different A. gerardii ecotypes were more successful in overall community recruitment and recruitment of microbes unique to the “home” environment, when growing at their “home site.” We found evidence for “home-field advantage” interactions between the host and host–root-associated bacterial communities, and the capability of ecotypes to recruit specialized microbes that were potentially linked to plant stress responses. Our study aids in a better understanding of the factors that affect plant adaptation, improve management strategies, and predict grassland function under the changing climate.

Positive and negative feedbacks drive aboveground traits in rare plant species

“…Positive values of Hedges' g indicated positive plant-soil feedbacks in which the total biomass or percent ECM colonization was greater in soils conditioned by similar or opposite lineages compared to conspecific soils. These types of positive feedbacks in biomass and mycorrhizal colonization mediated by phylogenetically similar soil conditions represent a homefield advantage in which phylogenetically similar plant species readily share microbial mutualists due to a shared evolutionary history and symbiosis of host-associated microbial communities (Anacker et al 2014;Fitzpatrick et al 2018;Kohl 2020;Kazarina et al 2023). On the other hand, negative values of Hedges' g indicate negative plant-soil feedbacks in which the total biomass or percent ECM colonization was lower in soils conditioned by similar or opposite lineages compared to conspecific soils.…”