Amphibian skin bacteria display antifungal activity and induce plant defense mechanisms against Botrytis cinerea

Abstract

Botrytis cinerea is the causal agent of gray mold, which affects a wide variety ofplant species. Chemical agents have been used to prevent the disease caused bythis pathogenic fungus. However, their toxicity and reduced efficacy haveencouraged the development of new biological control alternatives. Recentstudies have shown that bacteria isolated from amphibian skin displayantifungal activity against plant pathogens. However, the mechanisms bywhich these bacteria act to reduce the effects of B. cinerea are still unclear.From a diverse collection of amphibian skin bacteria, three proved effective ininhibiting the development of B. cinerea under in vitro conditions. Additionally,the individual application of each bacterium on the model plant Arabidopsisthaliana, Solanum lycopersicum and post-harvest blueberries significantlyreduced the disease caused by B. cinerea. To understand the effect of bacteriaon the host plant, we analyzed the transcriptomic profile of A. thaliana in thepresence of the bacterium C32I and the fungus B. cinerea, revealingtranscriptional regulation of defense-related hormonal pathways. Our studyshows that bacteria from the amphibian skin can counteract the activity of B.cinerea by regulating the plant transcriptional responses.