Dr. Marion SCHILLING

Des forêts aux vignobles : adaptation des champignons dégradeurs de bois

Defended on December 16, 2022, at the Faculty of Sciences and Technology,  Vandoeuvre-Lès-Nancy

Thesis supervosors: Dr. Eric GELHAYE Lorraine University, Vandoeuvre-Lès-Nancy and Dr. Sibylle FARINE, University Haute Alsace

Abstract
Esca is one of the most devastating of the grapevine trunk diseases, that affect vineyards around the world.
One of its main symptoms is white rot, also called amadou. In white rot, Fomitiporia mediterranea (M.
Fischer) is the major species identified in Europe. White-rot fungi have evolved with their substrates and
may have developed specifically adapted degradation and detoxification mechanisms.
The main objective of this thesis is to understand how F. mediterranea is adapted to its substrate, grapevine
wood. The behavior of F. mediterranea during wood degradation on different wood species was monitored.
Carbon mineralization rate, wood mass loss, chemical composition in structural compounds and extractives,
fungal biomass production and protein secretion (secretome) upon cultures on sawdust were measured. In
a second step, the colonization of F. mediterranea on wood blocks was followed. In addition to the
physiological approach, a non-targeted metabolomic approach, with molecular networking, was used to
describe fungal and wood metabolomes during colonization.
F. mediterranea is able to degrade several wood species, including grapevine cv. ‘Gewurztraminer’ and
‘Riesling’, beech and oak, in sawdust or blocks, using a simultaneous degradation pattern. Parallely, the
fungus regulates its secretome in relation with its substrate: a larger number of oxidoreductases were
secreted on grapevine sawdust. This could be correlated with the observed degradation of grapevine lignin
and specialized metabolites, mainly stilbenes. Other factors than the structural and chemical composition
of the substrate, which could be involved in the adaptation of F. mediterranea, are discussed.
This work contributes to a better knowledge of the physiology of F. mediterranea, one of the key fungal
species in Esca complexe disease