Sporulation and germination of the biofungicide Bacillus subtilis on Echinacea and Lavandula plants in a horticulture production

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Production of organic horticultural plants is of great economical and environmental interest for Plant Select, animportant producer located in Quebec. However the biofungicides currently available, based on theplant-beneficial bacterium Bacillus subtilis, show little to no activity against the major fungal pathogens ofEchinacea and Lavandula. While B. subtilis is well known for its capacity to prevent fungal infections incertain agricultural plants, its survival and colonization on these plants is unknown. Also, our laboratoryrecently observed that B. subtilis forms dormant spores rapidly after colonizing a model plant, which decreasesits anti-fungal activities. Thus, we hypothesize that the lack of biofungicide effect of B. subtilis on Echinaceamight be due to a defective colonization of the plant, by premature entry dormancy, or both. To examine thishypothesis, we will follow colonization of leaves and roots through time after inoculation of Echinacea andLavandula with two different B. subtilis strains in Plant Select greenhouses. These results will provide us witha better understanding of B. subtilis growth dynamic and survival on plants. In a second aim, we will examinethe capacity of a variety of small organic molecules to stimulate the germination of B. subtilis dormant cells, inthe perspective of developing a biostimulant that could improve the activity of B. subtilis on plants. Thisproject will lead to a wider usage of organic fungicides in a perspective of sustainable plant production, thusproviding healthier work conditions and reduce the impact of horticultural production on the environment.