Soil Streptomyces communities in a prairie establishment reflect interactions between soil edaphic characteristics and plant host

Abstract

Diverse perennial grasslands represent an attractive goal for biofuel production, but are difficult to establish on formerly cultivated land. Nurse species have been used to aid in establishment, but the mechanisms by which facilitation occurs remain poorly understood. In this study, we test the hypothesis that nurse plants accumulate beneficial, pathogen-suppressive bacterial communities. Fourteen native, invasive, and crop plant treatments were planted in a field previously in a corn-soybean (Zea mays – Glycine max) rotation. Soil microbial community characteristics were measured, specifically the density of Streptomyces soil bacteria, and the density and proportion of pathogen-inhibitory Streptomyces isolates, due to the demonstrated role of this bacterial genus in soil-borne disease suppression. After one growing season, no significant differences were observed among plant treatments in Streptomyces density, the density or proportion of inhibitory isolates, or the intensity of inhibition observed against two common soil-borne pathogens. Streptomyces density and soil organic matter were significantly correlated among plots, though in differing directions in legumes and forbs. Our results suggest that one growing season is insufficient for perennial plants to condition soil for increased pathogen-suppression in a nutrient-rich agricultural soil.