Abstract
Esca, a Grapevine Trunk Disease (GTD), is of major concern for viticulture worldwide. Our study compares the fungal communities that inhabit the wood tissues of vines that expressed or not foliar esca-symptoms. The trunk and rootstock tissues were apparently healthy, whether the 10 year-old plants were symptomatic or not. The only difference was in the cordon, which contained white rot, a typical form of esca, in 79% of symptomatic plants. Observations over a period of one year using a fingerprint method, Single Strand Conformation Polymorphism (SSCP), and the ITS-DNA sequencing of cultivable fungi, showed that shifts occurred in the fungal communities colonizing the healthy wood tissues. However, whatever the sampling time, spring, summer, autumn or winter, the fungi colonizing the healthy tissues of asymptomatic or symptomatic plants were not significantly different. Forty-eight genera were isolated, with species of Hypocreaceae and Botryosphaeriaceae being the most abundant species. Diverse fungal assemblages, made up of potentially plant-pathogenic and -protective fungi, colonized these non-necrotic tissues. Some fungi, possibly involved in GTD, inhabited the non-necrotic wood of young plants, but no increase in necrosis areas was observed over the one-year period.
Highlights
Grapevine trunk diseases (GTDs) that affect vineyards are of major concern for the wine industry
Non-necrotic tissues were predominant in the trunks (Fig. 1c,d) and rootstocks of the esca foliar-symptomatic and asymptomatic plants
The results, based on the use of Single Strand Conformation Polymorphism (SSCP), clearly indicate that the fungal microflora changed over the year
Summary
Grapevine trunk diseases (GTDs) that affect vineyards are of major concern for the wine industry. The number of vines showing foliar symptoms of esca was not very high, but this figure increased steadily from 1.04% in 2003 to 3.23% in 2008 (during the same period, eutypa symptoms tended to decrease). (ii) About 10% of vines of surveyed varieties expressed trunk diseases foliar symptoms, e.g. Sauvignon variety in the Aquitaine region. (v) Regarding etiology, the symptoms that occur in the trunk, leaves and berries have been extensively described, indicating that if eutypa dieback symptoms markedly differ from those of esca and of BDA, differentiating between these two latter diseases often proves rather elusive, with Lecomte et al [13] recently providing evidence that foliar symptoms of esca showed transitory phases which overlapped with some BDA descriptions In order to understand the full complexity of the situation, it is essential to consider five additional points. (i) From one year to another the same vines do not necessary express foliar symptoms, so when we consider a period of several years the number of ‘‘esca-foliar symptomatic vines at least once’’ is far more relevant. (ii) About 10% of vines of surveyed varieties expressed trunk diseases foliar symptoms, e.g. Sauvignon variety in the Aquitaine region. (iii) Approximately 13% of French vineyards are unproductive, mainly because of these three diseases. (iv) Esca moderately affects the phenolic composition of grapes and decreases the sensory quality of wines, suggesting a dramatic increase in the economic importance of esca if no control methods are found [12]. (v) Regarding etiology, the symptoms that occur in the trunk, leaves and berries have been extensively described, indicating that if eutypa dieback symptoms markedly differ from those of esca and of BDA, differentiating between these two latter diseases often proves rather elusive, with Lecomte et al [13] recently providing evidence that foliar symptoms of esca showed transitory phases which overlapped with some BDA descriptions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
