Acquisition of Flavescence Dorée Phytoplasma by Scaphoideus titanus Ball from Different Grapevine Varieties.

Luciana Galetto,Domenico Bosco,Cristina Marzachì,Flavio Veratti,Dimitrios E Miliordos,Dario Sacco,Mattia Pegoraro

doi:10.3390/ijms17091563

Abstract

Flavescence dorée (FD) is a threat for wine production in the vineyard landscape of Piemonte, Langhe-Roero and Monferrato, Italy. Spread of the disease is dependent on complex interactions between insect, plant and phytoplasma. In the Piemonte region, wine production is based on local cultivars. The role of six local grapevine varieties as a source of inoculum for the vector Scaphoideus titanus was investigated. FD phytoplasma (FDP) load was compared among red and white varieties with different susceptibility to FD. Laboratory-reared healthy S. titanus nymphs were caged for acquisition on infected plants to measure phytoplasma acquisition efficiency following feeding on different cultivars. FDP load for Arneis was significantly lower than for other varieties. Acquisition efficiency depended on grapevine variety and on FDP load in the source plants, and there was a positive interaction for acquisition between variety and phytoplasma load. S. titanus acquired FDP with high efficiency from the most susceptible varieties, suggesting that disease diffusion correlates more with vector acquisition efficiency than with FDP load in source grapevines. In conclusion, although acquisition efficiency depends on grapevine variety and on FDP load in the plant, even varieties supporting low FDP multiplication can be highly susceptible and good sources for vector infection, while poorly susceptible varieties may host high phytoplasma loads.

Highlights

Flavescence dorée (FD), a severe grapevine yellows disease and a threat for wine production in many European viticulture areas [1], was first reported in Piemonte, northwestern Italy, in 1998 [2,3]
Acquisition efficiency depended on grapevine variety and on FD phytoplasma (FDP) load in the source plants, and there was a positive interaction for acquisition between variety and phytoplasma load
High proportions (34%–48%) of insects acquired FDP when caged on Arneis, Brachetto, Dolcetto and Freisa, while lower proportions were recorded for leafhoppers caged on FD-infected Timorasso and Moscato (22% and 9%, respectively)

Summary

Introduction

Flavescence dorée (FD), a severe grapevine yellows disease and a threat for wine production in many European viticulture areas [1], was first reported in Piemonte, northwestern Italy, in 1998 [2,3]. The disease is still present and epidemic in the southern part of the Region, between the Po valley and the Ligurian Appennin, which was recently (2014) included in the World Heritage Site list of Unesco (vineyard landscape of Piedmont: Langhe-Roero and Monferrato), on the ground of its “cultural landscape providing living testimony to winegrowing and winemaking traditions that stem from a long history” and its being an ‘outstanding example of man’s interaction with his natural environment’ [4] Wine production in this area traditionally involves several cultivars (cv), and the possibility that very susceptible grapevine varieties may improve the efficiency of vector transmission, and influence the disease epidemiology [5,6], is becoming a crucial question to address for management of FD in traditional grapevine growing areas of Piemonte. The leafhopper Orientus ishidae (Matsumura) has been found positive for the presence of FDP [16,17,18], but, in the absence of successful transmission to healthy plants, it cannot be considered a vector of the disease

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