Communication Dans Un Congrès Année : 2022

The physiology and drivers of Esca leaf symptom development in grapevine

Résumé

The development of Esca leaf symptoms is an erratic and misunderstood phenomenon, which varies among grape varieties and growing regions. Esca development is likely driven by multiple factors, such as pathogen populations, vine physiology, and climatic and viticultural conditions. Grapevine hydraulic functioning is at the core of interactions between biotic and abiotic factors during vascular pathogenesis. Host xylem tissues are colonized by many microbes, including the Esca pathogens. The ascent of sap is affected by soil water availability and climatic conditions. The present study focused on exploring (i) the impacts of Esca leaf symptom development on xylem hydraulic integrity, and (ii) the interactions between drought, climatic conditions, and leaf symptom incidence under controlled conditions and in the field. Leaf symptom development was associated with hydraulic failure caused specifically by xylem occlusion, and subsequent loss of hydraulic conductivity from trunks to leaf laminae. Xylem occlusion by tyloses was specific to Esca leaf symptoms, compared to other types of pre-mature or autumnal leaf senescence, and varied among grape varieties. Using mature potted plants uprooted from a vineyard and naturally infected by Esca pathogens, a long drought (-1MPa of predawn water potential over 3 months) was shown to inhibit Esca leaf symptom development, suggesting that vine water status plays a key role in Esca pathogenesis. Water relations and car-bon dynamics were compared during the combined effects of Esca and drought stress. Using bi-monthly leaf symptom monitoring in 50 vineyards in southern France (over several years) and statistical modelling, it was shown that soil humidity, evapotranspiration, and temperature were the key drivers of Esca incidence and phenology. These results provide new insights on the role of plant physiology and microbial communities, and their interactions with climate, as key drivers in Esca pathogenesis.

Dates et versions

hal-03752608 , version 1 (17-08-2022)

Identifiants

Citer

Giovanni Bortolami, Thibaut Fréjaville, Jérôme Pouzoulet, Ninon Dell'Acqua, Nathalie Ferrer, et al.. The physiology and drivers of Esca leaf symptom development in grapevine. the 12th International Workshop on Grapevine Trunk Diseases, Jul 2022, Mikulov, Czech Republic. pp.331, ⟨10.36253/phyto-13818⟩. ⟨hal-03752608⟩
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