Physiological responses of ‘Italia’ grapevines infected with Esca pathogens

Abstract

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.

Metagenomic Assessment Unravels Fungal Microbiota Associated to Grapevine Trunk Diseases

“…Changes in the plant morphology and physiology, as well as in biochemical functions, were also assessed as possible factors in the development of foliar symptoms. Ascorbate-Glutathione cycle was considered likely to be involved in grapevine susceptibility to fungi associated with the Esca complex [89]. Other hypotheses can contribute for the appearance of leaf symptoms, such as the disturbance of sap flow to the leaves on given xylem pathways altered by fungi, which is described as 'hydraulic dysfunction' [85,90,91], and annual infections by some fungi through pruning or green wounds [23,92]; however, more research is required to develop this hypothesis and to unravel the processes underlying colonization by these fungi [93].…”

Physiological and Molecular Responses of Vitis vinifera cv. Tempranillo Affected by Esca Disease

“…Trebbiano, describe a completely different behaviour in response to the viral infection, observing increases in AsA and decreases in DHA, but an unchanged redox state (AsA/DHA ratio). Other researchers have found dissimilar behaviours; Bruno et al [ 80 ] observed a lowered AsA/DHA ratio, while Sgherri et al [ 79 ] described a rise. This different behaviour of AsA in leaves might reflect the different varieties used, the different stages of infection, or even the interaction of phenols and flavonoids with the AsA to act as an H 2 O 2 elimination system [ 81 ].…”

Development of a molecular diagnostic to discriminate between Fomitiporia species and advancements in detection of the main grapevine decline‐related pathogens in propagating material and mature vines

“…Extensive surveys conducted worldwide revealed high percentage of infection in propagation material and in grapevine vineyards (Aroca et al., 2010; Carlucci et al., 2017; Dubrovsky & Fabritius, 2007; Liminana et al., 2009).…”

“…Pathogens associated with black foot disease belong to the genera Campylocarpon , ‘ Cylindrocarpon ’, Dactylonectria and Ilyonectria , based on a recent update of taxonomy (Agustí‐Brisach et al., 2013; Chaverri et al., 2011; Halleen et al., 2006; Lombard et al., 2014). Fungal isolates of the genus Ilyonectria and Dactylonectria associated with black foot disease were initially placed in the genus Cylindrocarpon , with C. destructans being the most frequently reported pathogen (Agustí‐Brisach & Armengol, 2013; Dubrovsky & Fabritius, 2007; Nascimento et al., 2001). Nevertheless, phylogenetic analysis revealed high genetic diversity within fungal isolates associated with black foot disease, which were placed in new genera and species.…”