Recherche de nouvelles variétés de triticale plus résistantes à l'oïdium

National audienceTo face the recent emergence of powdery mildew on triticale species, a collaborative programmebetween breeders, public research and technical institute has been conducted from 2008 to 2011 withfinancial support of French Agriculture Ministry. The aims were: a survey of disease evolution, a betterknowledge of pathogen virulence, finding new and varied resistance genes to create new resistantvarieties, a better understanding of genetic resistance and especially durable resistance. Now, we knowthat powdery mildew on triticale came from bread wheat formae speciales. We identified bread wheatgenes that seem to be efficient against triticale powdery mildew (Pm1-Chopin’s allele, Pm3d, Pm4,MlTo, MlSo especially and in a lesser extend MlSi2, MlTa2 et Mld). We identified resistant genotypes(genetic resources and material derived from new wheat x rye crosses) and potential molecular SSRmarkers from bibliography and from segregating triticale populations. Nevertheless, several pointsremain to be investigated more deeply

Interactions between Fusarium verticillioides and Fusarium graminearum in maize ears and consequences for fungal development and mycotoxin accumulation

Fungal interactions of Fusarium verticillioides and F. graminearum in maize ears and the impact on fungal development and toxin accumulation were investigated in a 2-year field study at two locations in France. Maize ears were inoculated either with a spore mixture of F. graminearum and F. verticillioides or using a sequential inoculation procedure consisting of a first inoculation with F. graminearum followed by a second with F. verticillioides 1 week later. Toxin and fungal biomass were assessed on mature kernels, using HPLC and quantitative PCR. Correlation between the levels of DNA and toxin was high concerning F. graminearum DNA and deoxynivalenol (R² = 0·73) and moderate for F. verticillioides DNA and fumonisin (R² = 0·44). Fusarium graminearum DNA either decreased in mixed inoculations or was not influenced by subsequent inoculations with F. verticillioides, compared to single inoculations. In contrast, F. verticillioides DNA either significantly increased or was not affected in mixed and sequential inoculations. In two of the replicates, it can be assumed that natural contamination by F. verticillioides was favoured by previous contamination with F. graminearum. Overall, the results suggest that F. verticillioides has competitive advantages over the F. graminearum strains. Additionally, the data provide, for the first time, key evidence that previous contamination by F. graminearum in maize ears can facilitate subsequent infections by F. verticillioides