Abstracts (first author)
Intense competition between arbuscular mycorrhizal mutualists in an in vitro root microbiome negatively affects total fungal abundancePDF
The root microbiome is composed of an incredibly diverse microbial community that provides services to the plant, including nutrient provision, increased stress resistance and pathogen exclusion. A major question in rhizosphere research is how species in root microbiome communities interact with each other, and their host. In the nutrient mutualism between host plants and arbuscular mycorhizal fungi (AMF), hosts exchange carbohydrates for mineral nutrients from the fungal partner. While there is high variation in the benefits AMF species provide to their host plants, we still know very little about how this variation drives fungal community composition and competition within the root microbiome. Here we use an artificial root system (in vitro root organ cultures) to investigate competitive interactions between a previously characterized ‘high’ and ‘low’ quality AMF species, under standard and high phosphorus availability. We show that negative competitive interactions between AMF species reduces overall fungal abundance by nearly 5-fold in the host root, and that negative interactions are less strong in the extraradical mycelial network. We find that the high-quality species, Rhizophagus irregularis, consistently outcompete the lower quality species, Glomus aggregatum, both inside and outside the host root. However G. aggregatum is not completely eradicated and still is able to reduce the abundance of R. irregularis. Phosphorus availability did not change the outcome of these interactions. We suggest that in vitro root systems offer a novel platform to study ecological dynamics in the root microbiome under precisely controlled conditions.