Stilbene polyphenols in the brown red wood of Vitis vinifera cv. Sangiovese affected by "esca proper"*

A number of stilbene polyphenols, dimers, trimers and tetramers of resveratrol (viniferins), which are typical Vitaceae metabolites, were extracted from asymptomatic wood (AW) and symptomatic brown-reddiscoloured wood (BRW) of Vitis vinifera cv. Sangiovese affected by “esca proper”, the trunk disease caused by the fungal complex Phaeomoniella chlamydospora , Phaeoacremonium aleophilum and Fomitiporia mediterranea . Resveratrol and the same types of viniferins were found in both AW and BRW, with the exception of α-viniferin, which was only detected in AW, and ampelopsin B, only in BRW. The total concentration of stilbene polyphenols was higher in symptomatic wood (3.7% in BRW vs 1.2% in AW). The absolute variationsin molar concentrations of each stilbene polyphenol (i) between BRW and AW (Δi = CiBRW - CiAW), were higherfor e-viniferin and resveratrol than the other compounds, while the relative variations (Δi/CiAW), were lower for ampelopsin H and isohopeaphenol, and higher for ampelopsin B, hopeaphenol, ampelopsin A, leachianol F and G, pallidol and e-viniferin (in descending order), than the relative variation for resveratrol. Aspects relating to the biosynthesis of stilbene polyphenols and their role in the host-esca pathogen interaction are discussed.