Amorpha canescens and Andropogon gerardii Recruit Comparable Foliar Fungal Communities Across the Steep Precipitation Gradient in Kansas

Tallgrass prairies in North America have endured substantial losses due to anthropogenic environmental change. Plant-associated phyllosphere fungi are a largely overlooked aspect of diversity in grassland systems. Phyllosphere fungi are important in plant health as pathogens, commensals, and potential mutualists. We aimed to determine how host plant species affected the community-level diversity of phyllosphere fungi across a steep precipitation gradient and two co-occurring prairie species – big bluestem (Andropogon gerardii, Poaceae) and leadplant (Amorpha canescens, Fabaceae). We sampled leaves of both plant species from five sites across a portion of the precipitation gradient in Kansas, USA, each site with a different mean annual precipitation (MAP; 615 mm – 1038 mm). Leaf disks were homogenized, and the extracted DNA was Illumina MiSeq sequenced to characterize the foliar fungal communities. We compared several richness and diversity estimates using Wilcoxon rank sum tests and multiple linear regression analyses and tested for compositional differences among the communities using permutational analysis of variance analogs (PERMANOVA). The data suggested minor differences in the fungal communities between the two hosts, whereas MAP had no effect. Similarly, linear regression analyses indicated no host or precipitation gradient effects on the fungal community composition. Both phyllosphere fungal communities and the factors affecting them in prairie systems remain poorly understood and results suggest that more research is needed to fully understand the compounding biodiversity which includes microbial communities within this system.