Fungal endophytes of the invasive grass Eragrostis lehmanniana shift metabolic expression in response to native and invasive grasses

Abstract

Plant-fungal interactions shape ecosystem dynamics and are increasingly recognized as important in the success of invasive plants. Although diverse fungal endophytes are known to inhabit plants, including grasses, the precise chemical mechanisms through which they influence their hosts remain inadequately understood. We used untargeted metabolomics to characterize substrate use and compound production of three fungal endophytes isolated from an invasive grass, Eragrostis lehmanniana, characterizing the metabolome of these fungal isolates grown alone (axenically) and in the presence of seeds from invasive E. lehmanniana and co-occurring native grasses (E. intermedia, Bouteloua curtipendula, and Leptochloa dubia). We found that each fungal isolate expressed a different metabolic profile in response to Eragrostis seeds, relative to seeds of non-Eragrostis native grasses. Coupled with results of germination trials, these findings suggest that plant-fungal interactions mediated by the fungal metabolome may play a key role in determining the success of a major invasive species.