Evaluation of λ-carrageenan, CpG-ODN, glycine betaine, Spirulina platensis and ergosterol as elicitors for the control of Zymoseptoria tritici in wheat

Wheat crops are constantly challenged by the pathogen Zymoseptoria tritici responsible for Septoria tritici Blotch (STB) disease. The present study reports the identification of five biocontrol compounds (λ-carrageenan, CpG-ODN, glycine betaine, Spirulina platensis and ergosterol) for the protection of wheat against STB in order to offer new alternative tools to farmers for sustainable crop protection. Screening of elicitors of wheat defenses was carried out through a succession of experiments: biocidal in vitro tests enabled to check for any fungicidal activities; glasshouse experiments allowed to determine the efficacy of a given compound in protecting wheat against STB; qRT-PCR biomolecular tests investigated the relative expression of 23 defense genes in treated versus untreated plants. We therefore demonstrated that λ-carrageenan, CpG-ODN, glycine betaine, Spirulina platensis and ergosterol are potential elicitors of wheat defenses. Foliar treatments with these compounds conferred protection of wheat by up to approximately 70 % against Z. tritici under semi-controlled conditions and induced both SA- and/or JA-dependent signaling pathways in the plant. These findings contribute to extend the narrow list of potential elicitors of wheat defenses against Z. tritici

Necroses racinaires et elaboration du rendement.

National audienc

L'etat sanitaire des racines.

National audienc

Evolution, dans un essai pluriannuel, de la résistance de Pseudocercosporella herpotrichoides au prochloraze

National audienc

Pourriture racinaire du pois proteagineux. Identification en France du complexe parasitaire

International audienc

Resistance to inhibitions of sterol C-14 demethylation in the cereal eyespot fungus, Pseudocercosporella herpotrichoides

*INRA, centre de VersaillesInternational audienc

Resistance of Ustilago nuda towards SDHIs in France: old or new story ?

Ustilago nuda is responsible for barley loose smut. It replaces grain heads with smut, or masses of spores which infect the open flowers of healthy plants and grow into the seed, without showing any symptoms. Therefore, the main control method is the use of fungicides, applied as seed dressing. Among various modes of action, succinate dehydrogenase inhibitors (SDHIs) are of great interest to control this disease, and are actually represented by carboxin, fluxapyroxad and fluopyram, in France. Specific resistance to carboxin and other SDHIs was first detected, in the 1980s and got widespread in many areas (Leroux, 1986). Carboxin was later replaced by other fungicides with greater intrinsic activities and broader disease spectra. The recent registration and use of 2nd generation SDHIs sets again the question of acquired resistance in U. nuda. This poster presents the phenotypic and genetic characteristics of resistant strains isolated from diseased barley heads, in field trials treated with SDHIs as seed dressing

A Plant Nutrient-and Microbial Protein-Based Resistance Inducer Elicits Wheat Cultivar-Dependent Resistance Against Zymoseptoria tritici

International audienceThe induction of plant defense mechanisms by resistance inducers is an attractive and innovative alternative to reduce the use of fungicides on wheat against Zymoseptoria tritici, the responsible agent of Septoria tritici blotch (STB). Under controlled conditions, we investigated the resistance induction in three wheat cultivars with different susceptible levels to STB as a response to a treatment with a sulfur, manganese sulfate, and protein-based resistance inducer (NECTAR Céréales). While no direct antigermination effect of the product was observed in planta, more than 50% reduction of both symptoms and sporulation were recorded on the three tested cultivars. However, an impact of the wheat genotype on resistance induction was highlighted, which affects host penetration, cell colonization, and the production of cell-wall degrading enzymes by the fungus. Moreover, in the most susceptible cultivar Alixan, the product upregulated POX2, PAL, PR1, and GLUC gene expression in both noninoculated and inoculated plants and CHIT2 in noninoculated plants only. In contrast, defense responses induced in Altigo, the most resistant cultivar, seem to be more specifically mediated by the phenylpropanoid pathway in noninoculated as well as inoculated plants, since PAL and CHS were most specifically upregulated in this cultivar. In Premio, the moderate resistant cultivar, NECTAR Céréales elicits mainly the octadecanoid pathway, via LOX and AOS induction in noninoculated plants. We concluded that this complex resistance-inducing product protects wheat against Z. tritici by stimulating the cultivar-dependent plant defense mechanisms