Biocontrol pseudomonads: interaction with the plants they protect and grazing predators that threaten their existence

在过去的15年里，我的实验室正在进行的研究一直集中在一种生防菌株--绿豆假单胞菌PA23上，它能够保护油菜免受由真菌病原菌菌核病菌(SS)引起的油菜菌核病的侵染。将PA23应用于油菜气生表面，直接通过抗菌作用抑制SS，并通过启动植物防御反应间接抑制SS。在拟议研究的第一个目标中，我们将把我们的注意力转移到地下，并探索PA23在根际存在如何影响植物生理。PA23在植物根部的定殖和基因表达将与PA23介导的油菜基因表达的变化一起使用RNA测序(RNAseq)进行研究。在目标2中，将探索PA23抗真菌代谢产物在与食草性捕食者卡氏棘阿米巴(Ac)相互作用中的作用。共培养将使我们能够通过RNAseq描述细菌对捕食者暴露的反应。AIM 3建立在我们最近的发现基础上，PA23不仅保护植物免受真菌侵袭，还促进植物生长。PA23和原生动物放牧对油菜根构型和基因表达的影响将被揭示。此外，将使用元基因组分析来阐明Ac的存在如何影响PA23的持久性和土壤群落的整体组成。总而言之，拟议的研究结果将提供一个前所未有的理解，即根际中的PA23如何影响油菜籽基因的表达和叶圈中对SS感染的敏感性。我们将首次揭示当根际中有一个或两个生物存在时，AC放牧对PA23基因表达和植物生理的影响。这项研究将为研究生和本科生提供广泛领域的培训，包括下一代测序、生物信息学、共聚焦显微镜和组织培养。这样的机会将确保学员做好充分准备，并对发现和应用科学工作部门的需求很高。这项工作的影响将通过研究复杂的原核-真核相互作用中的跨王国信号的科学家、作物产量增加形式的种植者以及整个社会在我们寻求安全、可持续的战略来养活地球上不断增加的人类数量方面实现。

For the past 15 years, research ongoing in my lab has focused on a biocontrol strain, Pseudomonas chlororaphis PA23, which is able to protect canola from sclerotinia stem rot caused by the fungal pathogen Sclerotinia sclerotiorum (Ss). Application of PA23 to the aerial surfaces of canola inhibits Ss directly through antibiosis and indirectly through priming of the plant defense response. In the first aim of the proposed research, we will shift our attention below ground and explore how the presence of PA23 in the rhizosphere influences plant physiology. PA23 colonization and gene expression on the plant roots will be investigated together with PA23-mediated changes in canola gene expression using RNA sequencing (RNAseq). In aim 2, the role of PA23 antifungal metabolites in the interaction with the grazing predator Acanthamoeba castellani (Ac) will be explored. Co-culturing will enable us to profile the bacterial response to predator exposure through RNAseq. Aim 3 builds upon our recent discovery that PA23 not only protects plants from fungal attack but also promotes plant growth. The impact of PA23 and protozoan grazing on canola root architecture and gene expression will be revealed. Additionally, metagenomic analysis will be employed to elucidate how the presence of Ac affects PA23 persistence and the composition of the soil community as a whole. Collectively, findings from the proposed studies will provide an unprecedented understanding of how PA23 in the rhizosphere impacts canola gene expression and susceptibility to Ss infection in the phyllosphere. We will reveal for the first time the effect of Ac grazing on PA23 gene expression and plant physiology when one or both organisms are present in the rhizosphere. This research will provide graduate and undergraduate students training in a wide breadth of areas including next generation sequencing, bioinformatics, confocal microscopy and tissue culture. Such opportunities will ensure trainees are well prepared and in high demand for both the discovery and applied science job sectors. The impact of this work will be realized by scientists investigating trans-kingdom signaling in complex prokaryotic-eukaryotic interactions, growers in the form of increased crop yields and society as a whole in our quest for safe, sustainable strategies for nourishing the ever-increasing number of humans on the planet.*****