Towards a better understanding of cultivar susceptibility to esca disease: results from a pluriannual common garden monitoring

Grapevine (Vitis vinifera L.) exhibits a high level of genetic and phenotypic diversity among the approximately 6000 cultivars recorded. This perennial crop is highly vulnerable to numerous fungal diseases, including esca, which is a complex vascular pathology that poses a significant threat to the wine sector, as there is currently no cost-efficient curative method^[1]. In this context, an effective approach to mitigate the impact of such diseases is by leveraging the crop’s genetic diversity. Indeed, susceptibility to esca disease appears to vary between cultivars, under artificial or natural infection. However, the mechanisms and varietal characteristics underlying cultivar susceptibility to esca are still unknown.

In this study, we monitored the expression of esca disease foliar symptom at the plant level for six years, on 46 cultivars planted in an experimental common garden in Bordeaux^[2]. First, a large gradient of varietal susceptibility was highlighted, with an average prevalence ranging from 0 to 24% of vines expressing esca foliar symptom per variety. This gradient was rather consistent across vintages, and the prevalence of grapevine dieback was significantly correlated with that of the leaf symptoms.

Secondly, we explored the relationships between esca disease prevalence and phenological and physiological traits phenotyped in the same plot. A negative correlation between δ¹³C and esca disease prevalence was demonstrated at the cultivar level, suggesting that varieties with higher water use efficiency are less prone to express esca. Moreover, our results suggest that low-vigour cultivars could be classified among the less susceptible ones, although these trends require further investigation. In contrast, neither phenological stages nor nitrogen status seem to be significant predictors of cultivar susceptibility to the disease.

Together, these results provide new insights into the potential of genetic resources for sustainable trunk diseases management, while opening up new perspectives for studying pathological and physiological determinants of their incidence.

Acknowledgements:

The authors would like to thank the teams from UE Vigne Bordeaux, SAVE and EGFV. This long-term monitoring was supported by the French Ministère de l’Enseignement Supérieur et de la Recherche, Château-Figeac (Saint-Emilion), PNDV (FranceAgrimer-CNIV), CIVB, Région Nouvelle-Aquitaine & INRAE.

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