Esca-linked symptomatology leads to pectin de-esterification and xyloglucan remodelling in grape berries
Ricardo M. F. da Costa (Portugal)1 2; Helena Santos (Portugal)3 4; Florent Weiller (Portugal)3; Jeanett Hansen (Denmark)5; Rute Amaro (Portugal)3; Cecília Rego (Portugal)6; Pedro Reis (Portugal)6; Bodil Jørgensen (Denmark)5; John P. Moore (South Africa)4; Ana Margarida Fortes (Portugal)3;
1 - LAQV-REQUIMTE, Molecular Physical-Chemistry R&D Unit, Department of Chemistry, University of Coimbra, Coimbra, Portugal; 2 - Centre for Functional Ecology (CFE), Associate Laboratory TERRA, Department of Life Sciences, University of Coimbra, Coimbra, Portugal; 3 - BioISI – Instituto de Biossistemas e Ciências Integrativas, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal; 4 - South African Grape and Wine Research Institute, Department of Viticulture and Oenology, Faculty of Agrisciences, Stellenbosch University, Matieland 7602, South Africa; 5 - Department of Plant and Environmental Sciences, Section for Plant Glycobiology, University of Copenhagen, Denmark; 6 - LEAF – Linking Landscape, Environment, Agriculture and Food Research Center, Associated Laboratory TERRA, Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal;
Keywords: Esca disease; Grape berry; Cell wall remodelling;
Abstract Topics: Theme 9: Cell Wall Function and Signaling in plant adaptation to Biotic and Abiotic Stresses
Type of Presentation: Poster
Abstract text: Esca is a major grapevine (Vitis vinifera) trunk disease, yet grape cell wall (CW) responses in this context remain poorly characterised. We compared CWs from symptomatic vs asymptomatic berries. Alcohol-insoluble residue (AIR) was characterised by trifluoroacetic acid (TFA) hydrolysis followed by gas chromatography-mass spectrometry (GC-MS), and fractionation with 1,2-diaminocyclohexanetetraacetic acid (CDTA) and 4M NaOH for Comprehensive Microarray Polymer Profiling (CoMPP) using 31 CW glycan-directed probes (monoclonal antibodies and carbohydrate-binding modules). Symptomatic berries showed pectin with lower methylesterification and increased Ca2+-pectate "egg-box" motifs, alongside reduced arabinogalactan-protein (AGP) epitope accessibility in both CDTA and NaOH extracts. Symptomatic berries also indicated higher glucose and a tendency to higher xylose, with lower fucose and galactose, and decreased probe binding to specific xyloglucan epitopes in NaOH fractions. These patterns suggest reduced xyloglucan side-chain substitution and tighter glycan-glycan association that consolidate the CW matrix. We propose that Esca-linked hydraulic stress accompanies wall remodelling towards a less porous matrix network enhancing barrier and turgor functions. This work adds a CW perspective to Esca and proposes a wall-remodelling mechanism, laying the groundwork for studies on impacts to grape and wine yield and quality.