New elicitors to protect wheat against Zymoseptoria tritici: biocontrol tools for IPM strategies

Elicitors are increasingly considered as promising biocontrol tools in the preventive treatment of plants against various diseases. These plant-immunity triggering compounds, also called “stimulators of plant natural defenses”, induce a general and systemic resistance of the plant to a large spectrum of biotic stresses. Today, focus is made on the crucial protection of wheat, as one of the most cultivated crop plants in the world. This crop is constantly challenged by a persistent and harmful fungus known as Zymoseptoria tritici, responsible of the Septoria Tritici Blotch (STB) disease. Control of this disease mainly depends on phytosanitary products, and the social and economic importance of wheat make it all the more urgent to identify and develop new elicitors as biocontrol tools in wheat IPM strategies.
This study focuses on the screening of nine molecules of various origins and structures for their potential eliciting properties to protect winter wheat against Zymoseptoria tritici. Three products were selected after screening trials in greenhouse conditions: EGL1, EGL4, and EGL5. They were efficient to reduce foliar disease symptoms from 40 to 80%. The biocide activity and phytotoxicity of these 3 products were evaluated directly towards the pathogen and the plant under laboratory and greenhouse conditions, respectively.
On the other hand, the triggered signaling pathways were investigated by studying the activity of the defense-related enzymes lipoxygenase (LOX), peroxidase (POX) and phenylalanine ammonia-lyase (PAL) in treated wheat leaves. In addition, the expression of five defense genes (lox, pal, pox2, chi, pr1) was studied by qRT-PCR in wheat leaves treated with these elicitors and/or inoculated with Zymoseptoria tritici. The corresponding results will be presented and discussed, with the perspective to investigate the influence of environmental parameters on the elicitation capacity and the efficacy of the elicitors in field conditions.