Senior Staff Scientist Oak Ridge National Laboratory Oak Ridge, Tennessee
Body of Abstract: The molecular events mediating the beneficial relationships between soil-borne microbes and host plants have yet to be fully characterized. Our previous genetic mapping and whole-genome resequencing studies identified a lectin receptor-like kinase gene (PtLecRLK1) that is associated with differential root colonization by the ectomycorrhizal fungus Laccaria bicolor among different Populus species. By introducing PtLecRLK1 into non-hosts and subsequently converting non-host to host, we have established PtLecRLK1 as a key regulator of L. bicolor colonization. We hypothesize that PtLecRLK1 functions as a receptor to perceive signals from L. bicolor and transduce it to downstream components and that its phosphorylation targets serve as its immediate downstream components. We applied phospho-proteomics to identify proteins with differential phosphorylation between L. bicolor-inoculated and un-inoculated PtLecRLK1 transgenic plants and identified several phosphorylation targets including a leucine-rich receptor-like kinase and a cGMP-dependent protein kinase. Biochemical assays were performed to validate protein-protein interactions and protein phosphorylation events. Furthermore, Omics analyses were performed to identify additional signaling components. Collectively, our study helps construct the entire PtLecRLK1-based signaling cascade that is responsible for specific molecular and physiological responses leading to L. bicolor root colonization.