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Transmission Competency of Single-Female Xiphinema index Lines for Grapevine fanleaf virus

First, second, and fifth authors: Institut National de la Recherche Agronomique–Université de Strasbourg. UMR 1131, SVQV ‘Santé de la Vigne et Qualité du Vin’, 28 rue de Herrlisheim, BP20507, 68000 Colmar, France; third, fourth, and sixth authors: Institut National de la Recherche Agronomique, UMR 6243, IBSV ‘Interactions Biotiques et Santé Végétale’ Laboratoire de Nématologie, 400 route des Chappes, 06903 Sophia Antipolis, France; and seventh author: Department of Plant Pathology and Plant-Microbe Biology, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456.

Grapevine fanleaf virus (GFLV) is vectored specifically from grapevine to grapevine by the ectoparasitic nematode Xiphinema index. Limited information is available on the vector competency of X. index populations from diverse geographical origins. We determined the transmissibility of two GFLV strains showing 4.6% amino acid divergence within their coat protein (e.g., strains F13 and GHu) by seven clonal lines of X. index developed from seven distinct populations from the Mediterranean basin (Cyprus, southern France, Israel, Italy, and Spain), northern France, and California. X. index lines derived from single adult females were produced on fig (Ficus carica) plants to obtain genetically homogenous aviruliferous clones. A comparative reproductive rate analysis on Vitis rupestris du Lot and V. vinifera cv. Cabernet Sauvignon showed significant differences among clones, with the single-female Cyprus line showing the highest rate (30-fold the initial population) and the Spain and California lines showing the lowest rate (10-fold increase), regardless of the grapevine genotype. However, there was no differential vector competency among the seven X. index lines for GFLV strains F13 and GHu. The implications of our findings for the dynamic of GFLV transmission in vineyards and screening of Vitis spp. for resistance to GFLV are discussed.

Additional keywords:longidorid.