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Funding: CTPS
Partership: UMR ISA Sophia Antipolis (Daniel ESMENJAUD)
Period: January 2015 > June 2018 (42 mo)
Contact EGFV: Nathalie OLLAT

Abstract: The two major pathways currently explored in France to control GFLV, a virus disease transmitted by the nematode Xiphinema index in soil, are the selection of fallow plants with antagonistic effects on the vector nematode and the creation of gate -greffe resistant to the latter in order to induce resistance to the virus. This proposal addresses the aspect of resistance to GFLV, a priority issue for rootstock confronted with the withdrawal of nematicides and conditions of declining recurrent yields in vineyards. The proof of the concept of resistance to the vector carried by the muscadine source NC184-4 was made by the proposing teams in the Nemadex A.B. rootstock approved in 2011 which strongly delays the viral transmission but has limited cultural abilities. With the aim of eventually creating a range of rootstocks resistant to GFLV (via nematode resistance) and adapted in particular to the various pedoclimatic conditions of the French vineyard, this muscadine source must be used optimally. This project aims to i) facilitate this creation by the knowledge of genetic determinism and histological mechanisms and by the molecular marking of vector resistance, and ii) to establish, by infectious soil tests, the durability of resistance induced by with respect to the virus and its link with the resistance genes (number ...) identified with respect to the nematode. Our first results obtained on segregated BC1 offspring suggest that nematode resistance is controlled by three dominant and independent genes. The segregation will be specified on a large number of individuals and will serve as a basis for the development of markers of the genes involved. The effect of different gene combinations will be studied in order to define a possible pyramiding strategy in new genotypes to increase the durability of resistance to the virus. This innovation will be decisive and perfectly complementary to the fallow-based control pathway studied as part of a global national project coordinated by the IFV.