Gérard Demangeat, and
Olivier Lemaire, Institut National de la Recherche Agronomique and Université Louis Pasteur de Strasbourg, UMR 1131, Unité Mixte de Recherche Santé de la Vigne et Qualité du Vin, BP 20507, 68021 Colmar, France; and
Marc Fuchs, Institut National de la Recherche Agronomique and Université Louis Pasteur de Strasbourg, and Department of Pathology and Plant-Microbe Biology, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456, USA
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Accepted for publication 8 September 2008.
The efficacy of cross-protection at mitigating the impact of Grapevine fanleaf virus (GFLV) on grapevines (Vitis vinifera) was assessed in two naturally infected vineyard sites. Test vines consisted of scions grafted onto rootstocks that were healthy or infected by mild protective strains GFLV-GHu or Arabis mosaic virus (ArMV)-Ta. Challenge GFLV infection via the nematode Xiphinema index was monitored over nine consecutive years in control and ArMV-Ta cross-protected vines by double-antibody sandwich--enzyme-linked immunosorbent assay using GFLV-specific antibodies, and in GFLV-GHu cross-protected vines by characterizing the coat protein gene of superinfecting isolates by immunocapture--reverse transcription--polymerase chain reaction--restriction fragment length polymorphism. Results were consistent with a significantly reduced challenge infection rate in cross-protected vines compared with control vines, more so in those protected with GFLV-GHu (19 versus 90%) than with ArMV-Ta (40 versus 65% in field A and 63 versus 90% in field B). However, the two mild strains significantly reduced fruit yield by 9% (ArMV-Ta) and 17% (GFLV-GHu) over 8 years and had a limited effect on fruit quality. Therefore, in spite of a great potential at reducing the incidence of challenge field isolates, cross-protection with natural mild protective strains GFLV-GHu and ArMV-Ta is not attractive to control GFLV because the negative impact on yield is a limiting factor for its deployment.
© 2008 The American Phytopathological Society