Antibiotic-producing bacteria in the genus Streptomyces can inhibit soil-borne plant pathogens, and have the potential to mediate the impacts of disease on plant communities. Little is known about how antibiotic production varies among soil communities in tropical forests, despite a long history of interest in the role of soil-borne pathogens in these ecosystems. Our objective was to determine how tree species and soils influence variation in antibiotic-mediated pathogen suppression among Streptomyces communities in two tropical dry forest sites (Santa Rosa and Palo Verde). We targeted tree species that co-occur in both sites and used a culture-based functional assay to quantify pathogen-suppressive capacities of Streptomyces communities beneath 50 focal trees. We also measured host-associated litter and soil element concentrations as potential mechanisms by which trees may influence soil microbes. Pathogen-suppressive capacities of Streptomyces communities varied within and among tree species, and inhibitory phenotypes were significantly related to soil and litter element concentrations. Average proportions of inhibitory Streptomyces in soils from the same tree species varied between 1.6 and 3.3-fold between sites. Densities and proportions of pathogen-suppressive bacteria were always higher in Santa Rosa than Palo Verde. Our results suggest that spatial heterogeneity in the potential for antibiotic-mediated disease suppression is shaped by tree species, site, and soil characteristics, which could have significant implications for understanding plant community composition and diversity in tropical dry forests.
Bibliographical noteFunding Information:
We gratefully acknowledge funding sources that supported this work, including a National Science Foundation (NSF) Career grant (DEB-1053237) to JSP and support to LLK from the National Institute of Food and Agriculture, US Department of Agriculture (Agreement No. 2011-67019-30330), and the Minnesota Agricultural Experiment Station. KKB was supported by a NSF Graduate Research Fellowship. We thank Daniel Perez Aviles for collecting soil and litter samples in the field.
© 2016, Springer-Verlag Berlin Heidelberg.
- Disease suppression
- Leaf litter
- Soil nutrients