Ultrastructural and chemical analysis of berry skin from two Champagne grapes varieties and in relation to Botrytis cinerea susceptibility

Abstract

Botrytis cinerea is a necrotrophic pathogen that causes one of the most serious diseases of the grapevine (Vitis vinifera), grey mold or Botrytis bunch rot. In Champagne, the Botrytis cinerea disease leads to considerable economic losses for winemakers and wines exhibit organoleptic defaults. The grapevine susceptibility increases with berry ripening, due to a loss of elasticity of the skin and an increase in its permeability. These processes may be related to the morphology of the grape berry skin and its chemical composition, in particular the amount and type of tannins, which provide a protective barrier against the fungus by inhibiting fungal enzymes that gives resistance against the pathogen.

This work investigated the ultrastructure of the grape skin and the amount and type of tannins throughout the berry development of the two main Champagne cultivars: Vitis vinifera cv. Pinot noir and Chardonnay in relation to in vitro susceptibility tests to Botrytis cinerea.

The comparative study between the two main grape cultivars of the Champagne region shows differences in the ultrastructure and composition of tannins, Chardonnay skins are characterized by an organized ultrastructure and elasticity of the cell wall related to a lower sensitivity to Botrytis cinerea. The type of tannins observed in Pinot noir skins is thicker and may contribute to cell wall rigidity and greater sensitivity to Botrytis cinerea.