Derepression of plant imnune responses: a new strategy to improve biocontol efficiency – DEREBIO

This project aims to develop an innovative method of biocontrol for the protection of the vineyard against cryptogamic diseases, and therefore to accelerate our independence from chemical pesticides. The objective is to transpose to the plot the concept of disinhibition of plant defence responses (demonstrated in controlled conditions) in order to increase the efficiency of protection induced by Plant Defence Inducers (PDIs). We have demonstrated in the laboratory and confirmed under controlled conditions that the enzymes type-2 Histone DeACetylases (HD2) negatively regulate the intensity of the immune responses of plants. The proposed strategy is therefore to combine disinhibition and activation of the immune responses. A natural molecule (of bacterial origin or from green chemistry), abundant, devoid of toxicity and inexpensive, has been identified as an efficient disinhibitor (declaration of invention DI-RV-21-0138). We have demonstrated in the laboratory and in the greenhouse, on herbaceous vine cuttings, that combining the disinhibition of plant defence responses with different PDIs (different chemical natures and modes of action) makes it possible to significantly increase the level of protection induced by these PDI applied alone against Plasmopara viticola, the downy mildew agent.

Two PDIs with different modes of action (elicitor and potentiator), respectively marketed and under development by Cérience, will be used in phytoprotection trials against P. viticola on the experimental plot of UMR SAVE specifically dedicated to the evaluation of biocontrol products (BC2grape) and on the network of experimental plots of Cérience. They will be applied alone or in combination with the defence responses disinhibitor. The determination of the efficiency of protection (monitoring of P. viticola development), and of the potential impact of these treatments on grapevine physiology and berry ripening will be carried out over three years. Tests will also be carried out to develop a solution allowing, from a unique application, a first action time of the disinhibitor and subsequent action time of the PDI.

The “disinhibition strategy” we propose will initially be aimed at socio-economic partners who are developing PDIs-based biopesticide strategies. In the long term, the entire wine industry will be able to be offered increasingly effective biopesticide solutions, making it possible to greatly reduce the application of chemical fungicides or copper.
The strategy developed in this project is in line with the objectives of the Ecophyto II+ plan to reduce the use of pharmaceutical products. It is based on the use of a natural molecule (disinhibitor), with no known toxicity and which significantly increases the activity of different PDIs. At the end of this project, we hope to be able to increase the efficiency of PDIs and generalize their use in the vineyard. This more effective biopesticide strategy at a lower cost will contribute to a more significant reduction in TFIs and will thus allow winegrowers using copper to limit/reduce inputs. This strategy is of interest both for the environmental impact (reduction of synthetic fungicides and copper) and societal (biocontrol products and application near areas occupied by the public, absence of residue).

The consortium partners have established regular collaboration for several years and have acquired solid experience in the use of PDIs and/or the disinhibition strategy. Each partner has a perfect knowledge of the skills of the other two, allowing us to work efficiently. The complementary knowledge and skills of the partners will allow us to develop this project based on data obtained from the molecular level to the vine stock, from the laboratory to the cultivated plot.