Serpentine soil has little influence on the root-associated microbial community composition of the serpentine tolerant grass species Avenula sulcata

Soil chemistry is a known influence on plant species distribution. Serpentine soils provide a striking example of this due to their discrete nature and long-studied influence on plant communities. Characterized by high levels of heavy metals and low levels of nutrients, they present a challenge for most plant species and allow only a relatively restricted set of species to grow. We do not yet fully understand the suite of adaptations present in serpentine endemics allowing them thrive where other plant species perform poorly or not at all. In this paper we explore the possibility that serpentine plants interact with a unique set of microbial endophytes, which allow them to make a living on this challenging substrate. To examine broad-scale patterns of microbial community composition we used phospholipid fatty acid analysis. To focus more narrowly on arbuscular mycorrhizal fungi community composition we used 18S rDNA markers specific to these fungi. We found only very weak evidence for a relationship with distinct microbial communities using either technique and no evidence to show increased reliance on AMF by serpentine plants. Our results indicate that adaptation of plants to serpentine soil does not involve adaptation to a unique community of soil mutualists.