Site- and Tissue-Specific Microbial Richness and Abundance in Slickspot Peppergrass: A Culture-Based Diversity Study

Abstract

Slickspot peppergrass (Lepidium papilliferum) is a rare, federally threatened mustard native to the sage-steppe of southwestern Idaho; it occupies microsites known as ‘slickspots’—clay-rich soil depressions that collect seasonal moisture. These environments are sensitive to disturbance and host fragile plant assemblages susceptible to habitat degradation. Despite the conservation importance of L. papilliferum, little is known about its associated microbiome. This project may aid in future studies of key plant microbe interactions and relationships between peppergrass and other native species. In this project, both endophytic (internal) and epiphytic (external) microbes were cultured from leaves and flowers of slickspot peppergrass collected across multiple sites in Idaho. Fungal isolates were grown on potato dextrose agar, and bacterial isolates on nutrient agar for optimal growth. Microbial richness, number of distinct colony morphospecies per plate, and total abundance using colony-forming units (CFUs) were quantified to measure alpha diversity within tissues of plants from the same sites and beta diversity across tissues