- Dec 2, 2019
Time & Location: 4pm; Room 1200 Molecular Plant Sciences Building
Subject: Bi-directional signaling along the microbiome-root-shoot axis
Host: Sheng Yang He
About the Speaker
University: Utrecht University
Abstract: Plants nurture a large community of root-associated microbiota, which provide them with essential services, such as enhanced nutrient uptake, growth promotion, and protection against pathogens. Our research is focused on understanding plant-beneficial functions encoded by the root microbiome and the role of plant genes facilitating these functions. Recently, we demonstrated that upon foliar pathogen infection, plant roots recruit a consortium of synergistic microbes to their rhizosphere that in turn trigger an immune response in the whole plant body. Using the Arabidopsis-Pseudomonas simiae WCS417 model, we identified the root-specific transcription factor MYB72 as a central regulator in the onset of this induced systemic resistance (ISR), which is typically effective against a broad spectrum of plant pathogens. Metabolomics revealed that MYB72 controls the biosynthesis of the iron-mobilizing coumarin scopoletin, which is excreted in the rhizosphere where it aids in iron uptake7. Scopoletin also has antimicrobial activity to which beneficial WCS417 is insensitive. Microbiome analysis of coumarin-deficient Arabidopsis mutants revealed that scopoletin functions in rhizosphere community assembly, possibly to promote recruitment of immunity-stimulating rhizobacteria to the roots.
A major question in plant-microbiome interactions research is: how do plant roots distinguish beneficial from harmful microbes? Recently, we showed that over 40% of the root-associated microbiota are capable of suppressing local root immune responses, therewith facilitating root colonization. The rhizosphere is a MAMP-rich environment. Hence, we believe that suppression of root immunity is an important function of the root microbiome as it prevents growth-defense tradeoffs that are typically associated with the activation of MAMP-triggered immunity. Understanding the mechanistic basis of plant-microbiome interactions provides a firm knowledge basis for the development of future crops that maximize profitable functions from the root microbiome.