Diversity and Abundance of Arbuscular Mycorrhizal Fungi and Soil Bacteria in Purshia tridentata Stands in the Sagebrush Steppe

Abstract

Soil microorganisms, including arbuscular mycorrhizal fungi (AMF) and nitrogen fixing bacteria, require better integration into ecological restoration programs as they might facilitate plant establishment. Both are believed to be critical for the establishment of native rangeland plant species such as Purshia tridentata. We evaluated the AMF and bacterial diversity and abundance from soils in 1) areas with undisturbed P. tridentata stands in rangelands of north-central Oregon and 2) areas where P. tridentata was eliminated because of wildfires. We collected soil from three locations 1) areas with undisturbed P. tridentata stands in rangelands of North-central Oregon and 2) areas where P. tridentata was eliminated because of wildfires. We also collected roots from live P tridentata plants. We used 16s rRNA gene and ITS amplicon sequencing to determine and compare bacterial and AMF microbiomes. We wanted to evaluate the soil bacteria to the family level to determine the presence of the Frankiaceae family, and the AMF to the species level to evaluate which AMF species colonized this plant. Bacterial and AMF diversity did not vary between locations, but diversity and abundance of both parameters differed in roots (P < 0.05) from those of soils. AMF abundance in roots was dominated by Claroideoglomus and Glomus. The major bacterial familiy detected in soil samples was Chthoniobacteraceae, while Frankiaceae was present to a very low extent. Our results suggest that current microbial communities in the study area are homogeneous instead of being affected by the elimination of P. tridentata. However, our data reveals the current mycorrhizal communities associated with P. tridentata which can be used for restoration purposes.