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Objectives

Premunition or cross-protection is a phenomenon discovered almost a century ago and used for decades as a biocontrol method to protect plants from damage caused by viral diseases. It consists in inoculating variants with little or no aggression to protect the plant against subsequent infection by related aggressive variants. In order to develop this biocontrol method effectively and sustainably in the vineyard, our objectives are to :

• set up greenhouse and vineyard trials to test the efficacy of this method against Grapevine fanleaf virus (GFLV), the main agent responsible for short-nood disease
• study the diversity and evolution of GFLV
• determine the factors and mechanisms underlying this phenomenon, for which the current lack of knowledge hinders the deployment of this method for many pathosystems.

Approaches and resources

GFLV-infected vines showing few or no symptoms were selected from foci heavily affected by the disease in various French wine-growing regions (Alsace, Burgundy, Champagne, Rhône Valley and Bordeaux). Some of these candidate plants - whose variant composition is determined by high-throughput sequencing (HTS) - have been multiplied and will be replanted by 2027 in their regions of origin in a dozen pilot trials. Phenotypic monitoring (absence of symptoms and significant yield losses linked to infection by aggressive variants) and HTS will enable us to determine whether the candidate plants are protected from the serious effects of the disease and from superinfection by other GFLV variants.

In parallel, experiments are being carried out on herbaceous hosts (Nicotiana benthamiana and Arabidopsis thaliana) under controlled conditions to determine the parameters impacting premunition (genetic relatedness required between protective and challenger variants, time interval between inoculations, etc.).

Staff (ViVe team)

• Meryem ALALOUT
• Aleksandar BLAGOJEVIC
• Myriam HAGEGE
• Jean-Michel HILY - IFV
• Olivier LEMAIRE
• Pierre MUSTAIN
• Anne SICARD
• Emmanuelle VIGNE

Funding

Vaccivine 2

ProtectMe

Results

In order to select low-aggression GFLV variants native to Champagne, we studied two heavily short-nouled Chardonnay plots in this region. The vines selected for the study were classified into three categories: (i) asymptomatic GFLV-free vines (uninfected vines), (ii) virus-infected vines with weak symptoms (premunition candidates) and (iii) virus-infected vines with strong symptoms. The four premunition candidates are currently being evaluated in trials to be carried out in Champagne in 2022.

Characterization of grapevine fanleaf virus isolates in ‘Chardonnay’ vines exhibiting severe and mild symptoms in two vineyards. Viruses, 14(10). https://doi.org/10.3390/v14102303