Comparison of phosphonate derivatives (fosétyl-Al, PK2) efficacy to that of BTH as grapevine defence elicitors against Plasmopara viticola

National audienc

La résistance aux fongicides : Quoi de neuf docteur ?

National audienc

Impact of grapevine downy and powdery mildew diversity on the efficacy of phosphonate derivatives described as stimulators of plant defences

International audienc

Statement of strawberry powdery mildew (Podosphaera aphanis) resistance to DMI fungicides in France

National audienceIn this study, a simple bioassay on leaf discs was used to establish the state of fungicide sensitivity distribution of strawberry powdery mildew (Podosphaera aphanis) to two triazole DMI fungicides, myclobutanil and penconazole. The distribution of the EC50 of 23 isolates shows a progressive variation depending on the different mechanisms involved in the resistance acquisition process. Discriminatory doses (5 or 2 mg/L) of myclobutanil and penconazole were selected to identify highly resistant individuals or detect significant shifts in the field populations. 73.9% of isolates were less sensitive to a DMI and 47.8% exhibited less sensitivity to both fungicides. This is the first study to measure P. aphanis sensitivity to DMI fungicides in France.Une méthode permettant d’évaluer la sensibilité aux fongicides de plusieurs souches d’oïdium du fraisier (Podosphaera aphanis) collectés au cours des années 2006-2007 dans différents bassins de production en France a été mise au point sur disques de feuilles de fraisier en survie. Les ED50 obtenus pour le myclobutanil varient de moins de 0,1 à 14, 67 mg/L et celles pour le penconazole sont comprises entre 0,04 et 4,2 mg/L. Un facteur supérieur à 100 sépare la souche la plus sensible des plus résistantes. Des doses discriminantes, respectivement de 5 et 2 mg/L permettent de sélectionner les individus les plus résistants et de suivre l’évolution de la sensibilité des populations au champ. Une analyse de la résistance montre qu’il existe une résistance croisée positive entre les souches résistantes au myclobutanil et au penconazole. 73,9% des souches testés sont résistantes à l’un des deux fongicides IDMs et 47,8% montrent une sensibilité réduite au deux molécule

Oïdium de la vigne : point sur la diversité et la résistance aux fongicides en 2009

National audienc

«BioMolChem», a tool to assess the defense status of grapevines after stimulations or not: from laboratory to the field

Stimulating plant defenses is a promising alternative method for limiting pesticide use in agriculture. To assess the defense status of the grapevine we have developed a triple approach called "BioMolChem". - Biological tests measure the efficacy of grapevine defenses against two major biotrophic pathogens (Erysiphe necator, Plasmopara viticola). - Molecular assays by q-RT-PCR show the expression patterns (over-expression or repression) of 24 genes involved in grapevine defenses, and they can then be correlated or not with the level of protection, - BioChemical analyses of phenylpropanoides by HPLC are used to quantify and identify molecules of interest, and correlate them with specific gene expression (stilbene biosynthesis) and the acquired protection. This tool was tested on leaves after stimulation by different elicitors (acibenzolar-S-methyl, phosphonates), on grapevine: Cabernet Sauvignon cv., resistant genotypes to powdery and downy mildew, and in the vineyard. We obtained correlations between the expression of various genes and with the level of protection. Similarly, we found correlations between the presence of known and unknown polyphenols and the level of protection. Resveratrol, a well-known phytoalexin of the grapevine, is a good marker of defense status but not of protection. Therefore, we now have an valuable tool for understanding the defense and protection status of the grapevine in laboratory and field experiments

Resistance of Plasmopara viticola: diversity and fitness of resistant isolates to QoI fungicides

International audienc

"BioMolChem" : a tool to assess the defense status of grapevines after stimulations or not of cultivar of resistant genotypes, from genes to the field

Congrès : Ist World Congress on the Use of Biostimulants in Agriculture ; Strasbourg (France) - (2012-11-26 - 2012-11-29)International audienceStimulating plant defenses or resistant plant varieties is promising as an alternative method for limiting pesticide use in agriculture. To assess the defense status of the grapevine we have developed a triple approach called BioMolChem. The biological tests measure the efficacy of grapevine defenses against two major biotrophic pathogens (Erysiphe necator, Plasmopara viticola). Molecular assays by q-RT-qPCR show the expression patterns (over-expression or repression) of 20 genes involved in grapevine defenses, and they can then be correlated or not with the level of protection. Biochemical analyses of phenylpropanoides by HPLC are used to quantify and identify molecules of interest, and correlate them with specific gene expression (stilbene biosynthesis) and the acquired protection. This tool was tested on leaves (Cabernet Sauvignon) after stimulation by different elicitors (benzothiadiazole, phosphonates), on grapevine, Cabernet Sauvignon, genotypes resistant to powdery and downy mildew, and in the vineyard. We obtained correlations between the expression of PR-protein genes and genes coding for biosynthesis pathways (stilbene, tryptophan) and with the level of protection. Similarly, we found correlations between the presence of known and unknown molecules and the level of protection. Resveratrol, a well-known phytoalexin of the grapevine, is a good marker of defense status but not of protection. Therefore, we now have available a tool for understanding the defense and protection status of the grapevine in laboratory and field experiments