Physiological features were examined of a 20-year-old Vitis vinifera ‘Italia’ table grape vineyard cropped in Apulia, Italy. Healthy vines with no foliar symptoms and any indications of wood or berry alterations, vines with natural wood infections by Phaeoacremonium minimum (syn. P. aleophilum) and Phaeomoniella chlamydospora showing brown wood streaking symptoms, and vines naturally infected with P. minimum, P. chlamydospora and Fomitiporia mediterranea with brown wood streaking and white rot symptoms, were surveyed. Bleeding xylem sap, collected at bud-break from healthy vines showed the greatest total ascorbic acid level, while vines with brown wood streaking and white rot had the greatest viscosity coefficient, glutathione concentration, and plant growth regulator activities. Compared to healthy vines, leaves of wood affected vines, sampled during the unfolded leaf, fruit setting, cluster closing and bunch ripening vine growth stages, had reduced fresh and dry weights, total chlorophyll concentrations, and increased leaf surface area. Low ascorbic acid and reduced glutathione concentrations, weak redox state, and moderate levels of dehydroascorbic acid and oxidized glutathione were also detected in these vines. Analyses also detected reduced activities of dehydroascorbate reductase, ascorbate free radical reductase and glutathione reductase in diseased vines. The cell membrane damage, associated with lipid peroxidation, was coupled with high hydrogen peroxide concentrations. These changes could contribute to the cell death of leaves and foliar symptom development. The ascorbate-glutathione cycle supports grapevine susceptibility to Esca complex-associated fungi.

This study investigated some physiological features in a 20-year-old 'Italia' vineyard cropped in Apulia, Italy. Five vines with brown-wood-streaking associated to Phaeoacremonium minimum (sin. Pm. aleophilum) and Phaeomoniella chlamydospora (BWSV), five with brown-wood-streaking and white-rot caused by Fomitiporia mediterranea (BWSWRV) and five healthy vines (HV) were surveyed. Bleeding xylem sap (BXS) collected at bud-break, symptomless and symptomatic leaves taken during stretched-out leaves, fruit setting, cluster closing and bunch ripening phenological phases were characterized. BXS from HV showed the highest total ascorbic acid level, while BWSWRV had the highest viscosity coefficient, glutathione concentration and growth regulators activity. Low fresh and dry weight, total chlorophyll concentration and the hight leaf surface, hydrogen peroxide and cell membranes damage were detected in leaves of diseased vines. Symptomless and symptomatic leaves of BWSV and BWSWRV exhibited low concentrations of ascorbic acid, reduced glutathione and redox state; moderate levels of dehydroascorbic acid and oxidized glutathione. Higher dehydroascorbate reductase and low ascorbate free radical reductase and glutathione reductase activities were showed by leaves collected from diseased vines. However, no differences were detected in ascorbate peroxidase activity. The decrease of oxidative status alters cell membranes integrity and could contribute to cell death and symptoms development on leaves.