Development of a new indicator of grape skin ripening in relation to Botrytis cinerea susceptibility

Abstract

The bunch rot induced by Botrytis cinerea is an important disease of grapevine that causes a diminution of grape quality and a considerable yield loss leading to an economic loss. Currently, the most common methods to control this rot are canopy management and the use of fungicides, which has harmful effect on the environment and human health .The main grape barrier against pathogen remains grape skin, the resistance includes many factors which can be physical, biochemical or anatomical. Therefore, a new indicator based on these parameters of grape skin needs to be developed to evaluate the rot sensitivity and reduce the use of fungicides in vineyards. During ripening, B. cinerea sensitivity increases due to a loss of skin elasticity and an increase of grape skin porosity. These modifications are the result of different enzymatic activities (pectin methyl esterase (PME), polygalacturonase (PG), xyloglucan endotransglucosylase (XET)) that degrade the skin parietal polysaccharides. A combined physical and biochemical approach was developed to evaluate the Botrytis cinerea susceptibility of three Champagne varieties: Vitis vinifera cv. Pinot noir, Meunier and Chardonnay. Our results show that the skin ripening process differs between varieties and that our indicators (skin thickness, water availability, activity and gene expression of PME, PG and XET) can be used to describe the evolution of skin ripening profile for each cultivar and to explain the different susceptibility between three cultivars.