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

生产有机园艺植物是植物选择，一个重要的生产商位于魁北克省的经济和环境利益。然而，目前可用的生物杀菌剂，基于对植物有益的枯草芽孢杆菌，对紫锥菊和薰衣草的主要真菌病原体几乎没有活性。虽然枯草芽孢杆菌以其预防某些农业植物真菌感染的能力而闻名，但其在这些植物上的生存和定植尚不清楚。此外，我们的实验室最近观察到枯草芽孢杆菌在定植模式植物后迅速形成休眠孢子，这降低了其抗真菌活性。因此，我们假设枯草芽孢杆菌对紫锥菊缺乏生物杀菌剂作用可能是由于植物定植缺陷，或由于过早进入休眠，或两者兼而有之。为了验证这一假设，我们将在植物选择温室中接种紫锥菊和薰衣草两种不同的枯草芽孢杆菌菌株后，随时间跟踪叶片和根的定植情况。这些结果将有助于我们更好地了解枯草芽孢杆菌的生长动态和在植物上的生存。在第二个目标中，我们将研究各种小有机分子刺激枯草芽孢杆菌休眠细胞发芽的能力，以开发一种生物刺激剂，可以提高枯草芽孢杆菌在植物上的活性。从可持续植物生产的角度来看，该项目将导致有机杀菌剂的广泛使用，从而提供更健康的工作条件，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.