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

点击翻译按钮获取中文摘要

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.