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The Riesling vine variety has a natural resistance to the court-knot virus, which was not yet known. This is the conclusion of a research started more than 10 years ago by INRAE researchers, published on May 28 in an article in the journal Communications Biology.
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Work combining genetics and pathology has enabled them to discover a genetic factor that gives Riesling a natural resistance, a first in the fight against this virus which affects nearly 70% of French vineyards. This discovery paves the way for the first efficient and environmentally friendly genetic solution to control the grapevine grapevine disease.
Grapevine fanleaf virus (GFLV) is the main virus responsible for short-knot. Declines in production resulting from infections with this pathogen exceed 70% in the most severe cases and are responsible, in France, for economic losses of at least € 400 million per year1. It is transmitted to the roots of the plant by a tiny worm found in the soil: the nematode Xiphinema index. Sparing no organs, GFLV migrates to the aerial parts of the vine where it causes multiple damage, ranging from reduced symptoms to degeneration leading to death, including reduced vigor, fertility and production. . Preventive methods make it possible to reduce the impact of the disease, but no curative method is available to date.
However, INRAE researchers hold a promising lead, the result of research associating genetics and pathology, initiated 10 years ago and aimed at identifying natural resistance: the Riesling variety exhibits resistance to court-knotted. To identify such resistance, the scientists set up in a greenhouse an original experimental device reproducing the conditions of natural transmission of the virus in the vineyard. Extensive analyzes reveal that this natural resistance is specifically directed against GFLV and not against the X. index nematode. It is determined by a unique genetic factor, called rgflv1, and located on chromosome 1 of the vine genome. In addition to conferring resistance to shortneck, rgflv1 could be a factor in resistance to viruses more broadly, which would probably be distinct from those already discovered in other plant species.
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This discovery paves the way for an effective and environmentally friendly solution to control grapevine shortnose disease: the development of new rootstocks2 resistant to GFLV. These rootstocks will be able to have an impact on the longevity and sustainability of vineyards not only in France, but also throughout the world, by acting as a lever to fight against the decline of the vine due to the short-knot. More broadly, this work could serve as a basis for discovering a new type of resistance factors preserved in many cultivated species. Beyond its interest in contributing to a solution to agricultural problems linked to viral diseases, this study constitutes a springboard for accessing new fundamental information on plant-virus interactions.
Short knot virus: a real viral pandemic in the vineyard
Several avenues are being explored to fight against the court-knotted:
– the use of rootstocks tolerant to nematode vectors of the virus;
– biocontrol thanks to premunition, a method consisting in “vaccinating” plants using hypo-aggressive virus strains, or thanks to plants with a nematicidal effect making it possible to reduce the infectious potential of the soil;
– biotechnological approaches using genetically modified plants expressing different gene constructions.
But none of these leads has, to date, made it possible to develop a concrete and applicable solution, being either in the experimental state or still poorly accepted by society.
Reference
Djennane, S., Prado, E., Dumas, V. et al. A single resistance factor to solve vineyard degeneration due to grapevine fanleaf virus. Commun Biol 4, 637 (2021). https://doi.org/10.1038/s42003-021-02164-4
(1) Demangeat G, Esmenjaud D, Voisin R, Bidault JM, Grenan S, Claverie M (2005) The grapevine court-knotted: state of knowledge on this disease. Phytoma 587: 38-42
(2) The rootstock is the underground part of the vine: it constitutes the roots and carries the graft, an aerial part which in turn produces the grape. Each of these two parts are made up of different varieties with their own characteristics.
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