Antifungal activity of chili pepper extract with potential for the control of some major pathogens in grapevine

Background: In the recent years, biofungicides have drawn increasing interest in vineyard for a more sustainable integrated and copper-limited pest management. Among alternatives, botanicals could represent valuable tools, being rich sources of biologically active compounds. Conversely to the well-known antioxidant and biological properties in relation to health benefits, investigation on bioactivity of hot pungent Capsicum sp. products against fungal phytopathogens in vineyard is still scarce. Therefore, the present study aimed at exploring the biologically active compounds profile of a chili pepper (Capsicum chinense Jacq.) pod extract and its antimicrobial properties against some of the major fungal and Oomycetes pathogens of grapevine, including Botrytis cinerea Pers., Guignardia bidwellii (Ellis) Viala & Ravaz and Plasmopara viticola (Berk. & M.A. Curtis) Berl. & De Toni. Results: The ethyl acetate-extracted oleoresin from the most pungent varieties was rich in capsaicinoids and polyphenols (371.09 and 268.5 μg mg-1 dry weight, respectively). Capsaicin and dihydrocapsaicin, hydroxycinnamic and hydroxybenzoic acids and quercetin derivatives were the most abundant, while carotenoids represented only a minor fraction. The oleoresin was efficient to inhibit all three pathogenic fungi and ED50 values were determined, evidencing that G. bidwellii was the more sensitive (0.233 ± 0.034 mg mL-1 ). Conclusion: The results suggested a potentiality of chili pepper extract for the control of some important grapevine pathogens, their possible application being helpful for the recommended limitation in extensive use of copper in vineyard. The complex mixture of high amounts of capsaicinoids, associated to specific phenolic acids and other minor bioactive components might contribute for the observed antimicrobial action of chili pepper extract

Zebularine, a DNA Methylation Inhibitor, Activates Anthocyanin Accumulation in Grapevine Cells

Through its role in the regulation of gene expression, DNA methylation can participate in the control of specialized metabolite production. We have investigated the link between DNA methylation and anthocyanin accumulation in grapevine using the hypomethylating drug, zebularine and Gamay Teinturier cell suspensions. In this model, zebularine increased anthocyanin accumulation in the light, and induced its production in the dark. To unravel the underlying mechanisms, cell transcriptome, metabolic content, and DNA methylation were analyzed. The up-regulation of stress-related genes, as well as a decrease in cell viability, revealed that zebularine affected cell integrity. Concomitantly, the global DNA methylation level was only slightly decreased in the light and not modified in the dark. However, locus-specific analyses demonstrated a decrease in DNA methylation at a few selected loci, including a CACTA DNA transposon and a small region upstream from the UFGT gene, coding for the UDP glucose:flavonoid-3-O-glucosyltransferase, known to be critical for anthocyanin biosynthesis. Moreover, this decrease was correlated with an increase in UFGT expression and in anthocyanin content. In conclusion, our data suggest that UFGT expression could be regulated through DNA methylation in Gamay Teinturier, although the functional link between changes in DNA methylation and UFGT transcription still needs to be demonstrated

SEAWINES: Use of macroalgae as biostimulants against fungal diseases in grapevines

The outlook for climate change foresees major impacts on vineyards worldwide, shifting pathogens distribution and dynamics demanding more intense plant protection measures in certain regions, increasing viticulture's dependence on phytochemicals and pesticides. However, the European Commission is applying restrictions on their use, encouraging the development of more sustainable strategies efficient for disease control. Seaweeds represent an ecological alternative for a more sustainable production. Previous studies have shown that algae extracts contain compounds capable of reducing the abundance of plant fungal pathogens. Despite it, little is known about the molecular mechanism underlying this response. SEAWINES project is evaluating the efficacy of the foliar application of Ulva ohnoi and Rugulopteryx okamurae extracts to control powdery and downy mildew, in addition to testing their effect on grape and wine quality. To our knowledge, this is the first study evaluating R. okamurae biostimulant capacity and fungicidal effect in viticulture. This macroalgae is relevant since it is an invasive species in our coasts, causing incalculable economic and environmental burdens. We aim to 1- Reduce the usage of chemicals in grapevines; 2- Reduce fungal diseases in viticulture; 3- Valorize polysaccharides from seaweeds; 4- Increase the added-value to wines (ecological and quality); and 5- Provide an alternative use to seaweed biomass, contributing to bio-circular economy and reducing its accumulation in our coasts

«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

Methyl jasmonate/ethephon cotreatment synergistically induces stilbene production in "Vitis vinifera" cell suspensions but fails to trigger resistance to "Erysiphe necator"

Aim: The aim of the present investigation was to determine whether methyl jasmonate and ethylene could synergistically induce grapevine foliar cuttings (Vitis vinifera) defense mechanisms and enhance resistance to Erysiphe necator. Methods and results: We cotreated grapevine foliar cuttings (Cabernet- Sauvignon) with ethylene-releasing ethephon in association with methyl jasmonate. However, this cotreatment did not improve resistance to powdery mildew induced by MeJA or ethephon, alone. Quantitative PCR analysis performed on grape cell suspensions showed that the association ethephon/MeJA triggered an enhancement of phytoalexin biosynthesis by synergistically inducing PAL and STS genes. This gene expression was correlated with accumulation of stilbenes (antimicrobial compounds), assessed by HPLC analysis. However, ethephon seemed to inhibit MeJA-dependent induction of PR protein gene expression mainly for the first eighteen hours. Significance and impact of study: Since methyl jasmonate and ethephon can separately enhance grapevine resistance to Erysiphe necator, it was interesting to study the effect of the association of the two molecules on it. Although we observed a synergistic effect on phytoalexin production, no improved resistance against the fungus was obtained. These results can be exploited for the development of new pest control strategies in vineyard

"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

Une supplémentation en micronutriments restaure la synthèse protéique et réduit l'inflammation dans le cerveau de rats âgés

National audienceLe turnover protéique est un processus cellulaire clé pour assurer le renouvellement des protéines solubles et structurales pour un fonctionnement optimal des cellules. Dans le cerveau, au cours du vieillissement, la régulation de la synthèse protéique reste mal connue, bien qu'un déclin cognitif soit fréquemment observé avec l'âge. Le but de notre étude était donc de mieux comprendre la régulation de la synthèse protéique dans le cerveau de rats âgés. Deux groupes de rats âgés de 16 mois ont été nourris pendant 5 mois soit avec un régime contrôle, soit avec un régime supplémenté en rutine (5 g / kg d'aliment), vitamine E (~4x), A (2x), D (5x), sélénium (~10x) et Zinc (+44%) et comparés avec des rats adultes témoins (9 mois). Nous avons mesuré la synthèse protéique à jeun et à l'état nourri in vivo à l'aide d'une surcharge de valine marquée dans le cerebellum. En parallèle, nous avons mesuré l'expression de gènes marqueurs de l'inflammation et du stress oxydant dans l'hippocampe. Quel que soit l'âge, et contrairement à ce qui est généralement observé dans le foie, l'intestin ou le muscle, la synthèse protéique ne varie pas en fonction de l'état nutritionnel. Elle diminue de 8% avec l'âge, et la supplémentation en micronutriments permet de retrouver le niveau observé chez l'adulte. Les expressions des gènes du TNF et du Nrf2 augmentent avec l'âge, et là aussi, la supplémentation en micronutriments permet de retrouver le niveau observé chez les adultes. Ainsi, une supplémentation en micronutriments semble avoir des effets très positifs dans le cerveau des rats âgés. Nos résultats suggèrent qu'une inflammation pourrait être à l'origine d'une baisse de la synthèse protéique dans le cerveau au cours du vieillissemen

J. agric. food chem.

Grapevine is subject to diseases that affect yield and wine quality caused by various pathogens including Botrytis cinerea. To limit the use of fungicides, an alternative is to use plant elicitors such as benzothiadiazole (BTH). We investigated the effect of a fungicide (Pyrimethanil) and an elicitor (benzothiadiazole) on plant defenses. Applications for two consecutive years in the vineyard significantly reduced gray mold. Two and seven days after treatments, the expressions of 48 genes involved in defenses showed differential modulation (up- or down-regulation) depending on treatment. Some genes were identified as potential markers of protection and were linked to an increase in total polyphenols (TP) in leaves. Surprisingly, the fungicide also induced the expression of defense genes and increased the polyphenol content. This suggests that BTH acts as an efficient elicitor in the vineyard and that Pyrimethanil may act, in part, as a defense-inducing agent on the vine