Plant polysaccharides initiate underground crosstalk with bacilli by inducing synthesis of the immunogenic lipopeptide surfactin.
Some plant-associated bacteria such as Bacillus sp. can protect their host from pathogen ingress and this biocontrol activity correlates with their potential to form multiple antibiotics upon in vitro growth. However, our knowledge on antibiotic production by soil bacilli evolving on roots in natural conditions is still limited. In this work, antibiome imaging first revealed that the lipopeptide surfactin is the main bacterial ingredient produced in planta within the first hours of interaction with root tissues. We further demonstrated that surfactin synthesis is specifically stimulated upon perception of plant cell wall polymers such as xylan or arabinogalactan, leading to fast accumulation of micromolar amounts in the root environment. At such concentrations, the lipopeptide may not only favour the ecological fitness of the producing strain in term of root colonization, but also triggers systemic resistance in the host plant. This surfactin-induced immunity primes the plant to better resist further pathogen ingress, and involves only limited expression of defence-related molecular events and does not provoke seedling growth inhibition. By contrast with the strong response mounted upon perception of pathogens, this strongly attenuated defensive reaction induced by surfactin in plant tissues should help Bacillus to be tolerated as saprophytic partner by its host.
Mass Spectrometry Laboratory (LSM/GIGA-R), Chemistry Department, University of Liège, Liège, 4000, Belgium.
Delphine
D
Debois
URVVC-EA 4707, Stress, Défenses et Reproduction des Plantes, Université de Champagne-Ardenne, Reims, BP 1039, France.
Olivier
O
Fernandez
Wallon Center for Industrial Biology, Gembloux Agro-Bio Tech, University of Liège, Gembloux, 5030, Belgium.
Laurent
L
Franzil
Wallon Center for Industrial Biology, Gembloux Agro-Bio Tech, University of Liège, Gembloux, 5030, Belgium.
Emmanuel
E
Jourdan
Molecular Biology (GxABT), Molecular and Cellular Epigenetics (GIGA), University of Liège, Gembloux, 5030, Belgium.
Alix
A
de Brogniez
Molecular Biology (GxABT), Molecular and Cellular Epigenetics (GIGA), University of Liège, Gembloux, 5030, Belgium.
Luc
L
Willems
URVVC-EA 4707, Stress, Défenses et Reproduction des Plantes, Université de Champagne-Ardenne, Reims, BP 1039, France.
Christophe
C
Clément
URVVC-EA 4707, Stress, Défenses et Reproduction des Plantes, Université de Champagne-Ardenne, Reims, BP 1039, France.
Stephan
S
Dorey
Mass Spectrometry Laboratory (LSM/GIGA-R), Chemistry Department, University of Liège, Liège, 4000, Belgium.
Edwin
E
De Pauw
Wallon Center for Industrial Biology, Gembloux Agro-Bio Tech, University of Liège, Gembloux, 5030, Belgium.
Marc
M
Ongena
D000890:Anti-Infective Agents / Q000378:metabolism*; D001407:Bacillus / Q000378:metabolism*; D018407:Bacterial Physiological Phenomena; D055666:Lipopeptides / Q000378:metabolism*; D018521:Plant Physiological Phenomena; D018517:Plant Roots / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology*; D011134:Polysaccharides / Q000378:metabolism*; D013559:Symbiosis
D000890:Anti-Infective Agents; D055666:Lipopeptides; D011134:Polysaccharides