Importance of the C<sub>12</sub> Carbon Chain in the Biological Activity of Rhamnolipids Conferring Protection in Wheat against <i>Zymoseptoria tritici</i>
Rémi Platel,
Ludovic Chaveriat,
Sarah Le Guenic,
Rutger Pipeleers,
Maryline Magnin-Robert,
Béatrice Randoux,
Pauline Trapet,
Vincent Lequart,
Nicolas Joly,
Patrice Halama,
Patrick Martin,
Monica Höfte,
Philippe Reignault,
Ali Siah
Affiliations
Rémi Platel
Joint Research Unit N° 1158 BioEcoAgro, Junia, University Lille, INRAE, University Liège, UPJV, University Artois, ULCO, 48, Boulevard Vauban, BP 41290, F-59014 Lille CEDEX, France
Ludovic Chaveriat
ULR 7519—Unité Transformations & Agroressources, University Artois, UniLasalle, F-62408 Béthune, France
Sarah Le Guenic
ULR 7519—Unité Transformations & Agroressources, University Artois, UniLasalle, F-62408 Béthune, France
Unité de Chimie Environnementale et Interactions sur le Vivant (EA 4492), Université du Littoral Côte d’Opale, CS 80699, F-62228 Calais CEDEX, France
Béatrice Randoux
Unité de Chimie Environnementale et Interactions sur le Vivant (EA 4492), Université du Littoral Côte d’Opale, CS 80699, F-62228 Calais CEDEX, France
Pauline Trapet
Joint Research Unit N° 1158 BioEcoAgro, Junia, University Lille, INRAE, University Liège, UPJV, University Artois, ULCO, 48, Boulevard Vauban, BP 41290, F-59014 Lille CEDEX, France
Vincent Lequart
ULR 7519—Unité Transformations & Agroressources, University Artois, UniLasalle, F-62408 Béthune, France
Nicolas Joly
ULR 7519—Unité Transformations & Agroressources, University Artois, UniLasalle, F-62408 Béthune, France
Patrice Halama
Joint Research Unit N° 1158 BioEcoAgro, Junia, University Lille, INRAE, University Liège, UPJV, University Artois, ULCO, 48, Boulevard Vauban, BP 41290, F-59014 Lille CEDEX, France
Patrick Martin
ULR 7519—Unité Transformations & Agroressources, University Artois, UniLasalle, F-62408 Béthune, France
Unité de Chimie Environnementale et Interactions sur le Vivant (EA 4492), Université du Littoral Côte d’Opale, CS 80699, F-62228 Calais CEDEX, France
Ali Siah
Joint Research Unit N° 1158 BioEcoAgro, Junia, University Lille, INRAE, University Liège, UPJV, University Artois, ULCO, 48, Boulevard Vauban, BP 41290, F-59014 Lille CEDEX, France
The hemibiotrophic fungus Zymoseptoria tritici, responsible for Septoria tritici blotch, is currently the most devastating foliar disease on wheat crops worldwide. Here, we explored, for the first time, the ability of rhamnolipids (RLs) to control this pathogen, using a total of 19 RLs, including a natural RL mixture produced by Pseudomonas aeruginosa and 18 bioinspired RLs synthesized using green chemistry, as well as two related compounds (lauric acid and dodecanol). These compounds were assessed for in vitro antifungal effect, in planta defence elicitation (peroxidase and catalase enzyme activities), and protection efficacy on the wheat-Z. tritici pathosystem. Interestingly, a structure-activity relationship analysis revealed that synthetic RLs with a 12 carbon fatty acid tail were the most effective for all examined biological activities. This highlights the importance of the C12 chain in the bioactivity of RLs, likely by acting on the plasma membranes of both wheat and Z. tritici cells. The efficacy of the most active compound Rh-Est-C12 was 20-fold lower in planta than in vitro; an optimization of the formulation is thus required to increase its effectiveness. No Z. tritici strain-dependent activity was scored for Rh-Est-C12 that exhibited similar antifungal activity levels towards strains differing in their resistance patterns to demethylation inhibitor fungicides, including multi-drug resistance strains. This study reports new insights into the use of bio-inspired RLs to control Z. tritici.
