Seasonal and long-term consequences of esca grapevine disease on stem xylem integrity

• Published in: Journal of experimental botany 2021-05, Vol.72 (10), p.3914-3928
• Main Authors: Bortolami, Giovanni, Farolfi, Elena, Badel, Eric, Burlett, Regis, Cochard, Hervé H., Ferrer, Nathalie, King, Andrew, Lamarque, Laurent, Lecomte, Pascal, Marchesseau-Marchal, Marie, Pouzoulet, Jerome, Torres-Ruiz, Jose, Trueba, Santiago, Delzon, Sylvain, Gambetta, Gregory, Delmas, Chloe
• Format: Article
• Language: English
• Subjects: Environmental Sciences
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/erab117

Abstract Hydraulic failure has been extensively studied during drought-induced plant dieback, but its role in plant-pathogen interactions is under debate. During esca, a grapevine (Vitis vinifera) disease, symptomatic leaves are prone to irreversible hydraulic dysfunctions but little is known about the hydraulic integrity of perennial organs over the short- and long-term. We investigated the effects of esca on stem hydraulic integrity in naturally infected plants within a single season and across season(s). We coupled direct (ks) and indirect (kth) hydraulic conductivity measurements, and tylose and vascular pathogen detection with in vivo X-ray microtomography visualizations. Xylem occlusions (tyloses) and subsequent loss of stem hydraulic conductivity (ks) occurred in all shoots with severe symptoms (apoplexy) and in more than 60% of shoots with moderate symptoms (tiger-stripe), with no tyloses in asymptomatic shoots. In vivo stem observations demonstrated that tyloses occurred only when leaf symptoms appeared, and resulted in more than 50% loss of hydraulic conductance in 40% of symptomatic stems, unrelated to symptom age. The impact of esca on xylem integrity was only seasonal, with no long-term impact of disease history. Our study demonstrated how and to what extent a vascular disease such as esca, affecting xylem integrity, could amplify plant mortality through hydraulic failure.