A mutualistic interaction between Streptomyces bacteria, strawberry plants and pollinating bees

Abstract

Microbes can establish mutualistic interactions with plants and insects. Here we track the movement of an endophytic strain of Streptomyces bacteria throughout a managed strawberry ecosystem. We show that a Streptomyces isolate found in the rhizosphere and on flowers protects both the plant and pollinating honeybees from pathogens (phytopathogenic fungus Botrytis cinerea and pathogenic bacteria, respectively). The pollinators can transfer the Streptomyces bacteria among flowers and plants, and Streptomyces can move into the plant vascular bundle from the flowers and from the rhizosphere. Our results present a tripartite mutualism between Streptomyces, plant and pollinator partners. Microbes can establish mutualistic interactions with plants and insects. Here, Kim et al. show that Streptomyces bacteria can protect strawberry plants and honeybees from pathogens, can move into the plant vascular tissue from soil and from flowers, and are transferred among flowers by the pollinators.