Role of Poplar defense phytohormones in controlling the root microbiome

PI : Aurélie Deveau (UMR 1136 Interactions Arbres/Micro-organismes – IAM)

Co-applicants : Claire Veneault Fourrey (UMR 1136 Interactions Arbres/Micro-organismes – IAM); Caroline Plain (UMR 1434 Silva)

Collaborations : T. Tschaplinsky (OakRidge National Laboratory USA), C. Pan (OakRidge National Laboratory USA)

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Context — Microorganisms have a key role in forest ecosystem functioning: bacteria and fungi make available nutrients for trees by degrading dead plant and animal matter and by freeing minerals from rocks. In addition, some fungi and bacteria leave in close association with the roots of trees and contribute to the growth of trees and to their resistance to pathogens and climatic stresses. Although it is clear that trees have the ability to shape, at least for a part, the composition of their root associated microbial communities (called root microbiome), the mechanisms involved in this process are not well defined yet.

Objectives — We propose here to analyse how trees control their microbiome. In particular, we will test whether phytohormones involved in tree defence against pathogens have also a role in shaping the root microbiome using Poplar as a model system.

Approaches — We will construct genetically modified lines of Poplar that are altered in their perceptions or biosynthesis of ethylene, salicylic acid and jasmonic acid. Then we will assess in the laboratory the composition of the root microbiomes of the genetically modified lines and compare it to the ones of wild type roots.

Expected results and impacts — We anticipate that the proposed approach will permit to make major advances in our understanding of the ways by which trees select for and maintain a healthy microbiome. The proposed project is also a first step towards applied research aiming at using microbiomes to improve tree traits and is thus highly valuable for applied forestry.