MICROBIAL SYMBIONTS OF AN INVASIVE GRASS DIFFER IN URBAN AND EX-URBAN ENVIRONMENTS

Abstract

Buffelgrass (Cenchrus ciliaris) is a widespread, invasive plant in the Sonoran Desert. It establishes readily, weathers drought, alters fire regimes, and is costly and labor-intensive to eradicate. Investigating microbial symbionts of buffelgrass may identify factors that promote its establishment and rapid spread, as microbial symbionts of plants often are associated with enhancing host physiology and stress tolerance. The goal of this project was to evaluate the microbiome of buffelgrass under a wide range of environmental conditions in a portion of its invasive range. Specifically, we quantified the abundance, diversity, and composition of fungi associated with buffelgrass in urban areas (alleyways with poor soil and limited plant cover) and ex-urban areas (sites with natural soil and vegetation) in and near Tucson, AZ, USA. We isolated fungal endophytes from healthy roots and shoots and characterized distinctive strains via DNA barcoding following restriction fragment length polymorphism (RFLP) analysis. We found that endophytes of buffelgrass were more abundant in urban areas, but more diverse in ex-urban areas. The composition of endophyte communities also differed between urban and ex-urban sites. Our data are consistent with context-specific symbioses, in which buffelgrass recruits distinctive microbiomes under different environmental conditions. Future research will focus on identifying plant-microbe interactions that influence the fitness, germination, and stress tolerance of buffelgrass as an invasive plant.