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

有机园艺植物的生产对位于魁北克的重要生产商Plants Select具有重大的经济和环境利益。然而，目前可用的以植物有益细菌枯草芽孢杆菌为基础的生物杀菌剂，对紫锥菊和薰衣草等主要真菌病原体几乎没有或几乎没有活性。虽然枯草芽孢杆菌以其在某些农业植物上预防真菌感染的能力而闻名，但它在这些植物上的存活和定植尚不清楚。此外，我们的实验室最近观察到，枯草杆菌在模式植物上定植后迅速形成休眠孢子，这降低了其抗真菌活性。因此，我们推测枯草芽孢杆菌对紫锥菊缺乏生物杀菌作用可能是由于植物的有缺陷的定植，或由于过早进入休眠，或两者兼而有之。为了检验这一现象，我们将跟踪在植物选择温室中接种两个不同的枯草芽孢杆菌菌株紫锥菊和薰衣草后，叶片和根的定植情况。这些结果将为我们更好地了解枯草芽孢杆菌在植物上的生长动态和存活情况提供依据。在第二个目标中，我们将从开发一种可以提高枯草杆菌在植物上的活性的生物刺激剂的角度，检测各种有机小分子刺激枯草杆菌休眠细胞萌发的能力。该项目将从可持续植物生产的角度更广泛地使用有机杀菌剂，从而提供更健康的工作条件，并减少园艺生产对环境的影响。

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.