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

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. We found xylem occlusions (tyloses), and subsequent loss of stem ks, in all of the shoots with severe symptoms (apoplexy) and in more than 60% of the shoots with moderate symptoms (tiger-stripe), and no tyloses in shoots that were currently asymptomatic. In vivo stem observations demonstrated that tyloses were observed only when leaf symptoms appeared, and resulted in more than 50% PLC in 40% of symptomatic stems, unrelated to symptom age. The impact of esca on xylem integrity was only seasonal and no long-term impact of disease history was recorded. Our study demonstrated how and to what extent a vascular disease such as esca, affecting xylem integrity, could amplify plant mortality by hydraulic failure.

Minimal versus Intensive: How the Pruning Intensity Affects Occurrence of Grapevine Leaf Stripe Disease, Wood Integrity, and the Mycobiome in Grapevine Trunks

“…Besides vessel restructuring by the plant, pathogenic fungi can also interfere with the vessel integrity, e.g., by tissue degradation or by formation of occlusion [ 27 , 69 , 70 ]. Since wounds are the main gate for esca-associated pathogens to enter the vascular system, the risk of infection should decrease with reduced pruning measures on the trunk [ 1 , 71 , 72 ].…”

Activity of Trichoderma asperellum Strain ICC 012 and Trichoderma gamsii Strain ICC 080 Toward Diseases of Esca Complex and Associated Pathogens

“…The leaf symptoms have been reproduced only on very few occasions by the inoculation of different pathogens (Sparapano et al, 2001;Reis et al, 2016;Markakis et al, 2017). GLSD appears not to be linked to specific fungal agents but as a reaction of the plant to the activity of fungal wood colonization affecting the plant physiology and the quality of production (Calzarano et al, 2004b(Calzarano et al, , 2017aLorrain et al, 2012;Pouzoulet et al, 2014;Fontaine et al, 2016;Mary et al, 2017;Bortolami et al, 2021;Del Frari et al, 2021).…”

Fomitiporia mediterranea M. Fisch., the historical Esca agent: a comprehensive review on the main grapevine wood rot agent in Europe

“…Recent findings, however, suggest how these two hypotheses can be complementary and not exclusive, due to observed association between foliar symptoms, disruption of vessel integrity and presence of some "Esca disease"-associated pathogens presence in host trunks, which could elicit a distance-response (Bortolami et al, 2019). Stem vessel occlusion has been related to exacerbation of foliar symptom expression in the following growth season (Bortolami et al, 2021).…”