Plant community richness and foliar fungicides impact antibiotic inhibition, resistance, and resource use traits among soil Streptomyces

Authors: MICHALSKA-SMITH, MATTHEW - University Of Minnesota; Schlatter, Daniel; POMBUBPA, NUTTAPON - Chulalongkorn University; CASTLE, SARAH - University Of Minnesota; GRANDY, STUART - University Of New Hampshire; BORER, ELIZABETH - University Of Minnesota; SEABLOOM, ERIC - University Of Minnesota; KINKEL, LINDA - University Of Minnesota

Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/27/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Plants play essential roles as nutrient sources for soil microbes, where the identity and diversity of plant-derived nutrients are hypothesized to influence microbial competitive interactions. Further, foliar fungi can modify plant productivity with subsequent effects on soil microbes. However, linkages between foliar fungi, plant productivity, and soil microbial interactions is not well understood. We used a long-term plant diversity experiment with and without disruption of foliar fungi and characterized microbial interaction traits (antibiotic production, resistance, and nutrient use) among soil bacteria. Plant diversity had a strong influence on microbial interaction traits, where monocultures harbored a greater portion of antibiotic producing bacteria with greater niche overlap than species-rich plant communities. Moreover, the impact of foliar fungi disruption on microbial traits depended on plant community richness. In total, this work suggests that the diversity of plant-derived nutrients is a key mediator of microbial traits involved in competitive species interactions.

Technical Abstract: Plant-associated soil microbes (including Streptomyces) both influence and are influenced by their host plants, the latter in part because those plants modify soil resource quantity and diversity. Diverse plant communities deposit more, and more diverse, nutrients into the soil, and this deposition can be influenced by the above-ground community of foliar endophytes. The subsequent effects on soil microbial phenotypes are myriad—affecting inhibitory capacity, resource use, and antibiotic resistance. In this work, we consider the consequences of plant richness and disruption of the foliar fungal community on soil resource levels and root-associated Streptomyces phenotypes. We saw an increase in soil carbon, nitrogen, phosphorus, potassium, and organic matter in polyculture compared to monoculture, yet this increase was surprisingly offset when foliar fungal communities were disrupted. Nevertheless, we find that plant richness tended to affect Streptomyces phenotypes—increasing inhibitory capacity, altering resource-use profiles, and reducing antibiotic resistance—regardless of foliar fungicide application and independent of soil nutrient levels. Where foliar fungicide affected phenotypes, it did so differently in polycultures than in monoculture, for instance decreasing niche width and overlap in monocultures while increasing them in polyculture. The lack of expected correlations with soil resources suggest the need for further research looking more closely at soil resource diversity and particular compounds that were found to differ between treatments.