Biology subjects

Miclot, A.-S.

Publications and source records attributed to Miclot, A.-S..

3 recordsLinked to original sources

bioRxiv2026

Long-term performance of disease-resistant grapevine varieties: insights from an 8-year field monitoring across French vineyards

Breeding disease-resistant varieties (DRV) is a central strategy for reducing reliance on phytosanitary products. However, the successful deployment and long-term durability of these cultivars rely on acquiring field data across diverse production conditions, a step that remains frequently neglected, especially in perennial crops. Since 2018, the OSCAR observatory, a network of vineyard plots planted in France with varieties resistant to downy and powdery mildew, the two major pathogens of grapevine, has aimed to close this gap for viticulture. The observatory comprises over 199 commercial plots, covering 127 hectares across diverse agroclimatic conditions, all managed by winegrowers under their own production practices. The observatory currently monitors 30 disease-resistant grapevine varieties, tracking both their agronomic performance and the dynamics of key pathogens. Since 2018, while phytosanitary treatments have been reduced by an average of 79% compared to conventional plots, the incidence of downy and powdery mildew, remain low, even in years highly conducive to these diseases. However, the long-term survey also highlights the decline in efficacy of some resistances to downy mildew and the emergence of black rot, a disease effectively controlled by conventional phytosanitary programs. Beyond acting as a rapid warning system for resistance breakdown, the observatory promotes sustainable disease management in viticulture. It provides valuable insights to winegrowers on effective DRV management. It also delivers actionable feedback to breeders to guide more durable DRV breeding strategies. Highlights- OSCAR observatory monitors 199 plots of grapevine disease resistant varieties (DRV) - Grapevine DRV cuts fungicide uses by 79% while maintaining good disease control - Some resistances efficacy declines against downy mildew, but not powdery mildew - Black rot, a disease usually controlled by fungicide, is rising in OSCAR plots OSCAR provides useful feedback to breeders and winegrowers on DRV management

plant biology↗

bioRxiv2025

Balancing disease control efficacy, resistance durability, and economic outcomes: Insights from a participatory modeling study integrating grapevine cultivar deployment timing with fungicide treatments

1In this study, we developed, assessed and compared strategies for deploying disease-resistant grapevine cultivars in partnership with a wine cooperative in South-West France. In four collaborative workshops, cooperative managers and multidisciplinary researchers jointly designed six feasible deployment strategies. These scenarios, implemented within real vineyards, involve planting resistant cultivars (RC) in vineyards (i) more than 30 years old, (ii) on 3.3% of the older plots each year or (iii) on plots located in no-treatment zone (due to proximity to watercourses or human dwellings), with and without a fixed maximum percentage of resistant cultivars in the vineyard. The strategies were evaluated with the landsepi model, which simulates the spread and evolution of pathogens across agricultural landscapes in response to host resistance deployment. The assessment criteria included downy mildew control efficacy, resistance durability, decrease in fungicide use, and economic benefits for individual vineyards and the cooperative. These scenarios led us to study more specifically the effects of two little-studied factors: (i) the presence or absence of fungicide applications and (ii) the massive or progressive introduction of resistant cultivars. Fungicide application substantially decreases the risk of resistance breakdown and complements the epidemiological control provided by resistant cultivars, particularly when the fitness costs of virulence are low. The probability of pathogens adapted to RC becoming established was generally lower with progressive than massive RC introduction; however, when establishment did occur, the time to establishment was shorter for progressive strategies at a cropping ratio [≥] 50%. Ultimately, the choice of RC introduction strategy had a minimal overall impact on disease control due to compensatory epidemiological and evolutionary processes, including dilution effects, and the probability and timing of resistance breakdown. These results are discussed in the broader framework of action-research approaches and the challenges and opportunities for resistant cultivar adoption by vine-growers. Our study highlights the potential of participatory approaches for developing practical, scientifically grounded strategies for sustainable viticulture.

evolutionary biology↗

bioRxiv2025

A multivirulent Plasmopara viticola strain from Cilaos on Reunion Island breaks down Rpv1, Rpv3.1 and Rpv10 mediated resistance of grapevine

AbstractGrapevine downy mildew, caused by Plasmopara viticola, is one of the most destructive diseases in viticulture. Resistance-based management strategies rely on grapevine varieties carrying major resistance loci (Rpv). Although breakdown of several loci has been reported, Rpv1 had remained effective until now. Here, we provide the first evidence of Rpv1 breakdown by P. viticola in Cilaos on Reunion Island (France) and the first case of a strain simultaneously overcoming three resistances of grapevine. We combined pathogenicity assays with whole-genome sequencing to characterize a P. viticola strain collected in Cilaos in 2023, alongside a panel of eight reference strains of known virulence. Hypersensitive response and sporulation were assessed for each strain on Chardonnay (susceptible variety) and four resistant varieties carrying Rpv1, Rpv3.1, Rpv10, or Rpv12. The strain collected in Cilaos was able to overcome not only Rpv1 but also Rpv3.1 and Rpv10. On Rpv1, we observed a complete loss of host recognition with high sporulation. On Rpv3.1, the phenotype was consistent with previous breakdowns, and the strain carried the vir1 allele previously described in France. By contrast, the breakdown of Rpv10 differed from that reported in European populations: whereas European strains displayed only partial breakdown of resistance, the strain of Cilaos showed complete loss of host recognition with high sporulation. Moreover, genomic analyses revealed a novel mutation, a large homozygous deletion in the corresponding avr locus. Our genomic data analyses further suggests that this P. viticola strain shares a genetic background with populations from mainland France, raising serious concerns about the potential emergence and spread of multivirulent lineages in Europe. These findings highlight the need for large-scale virulence monitoring of P. viticola and improved strategies for the sustainable management of grapevine resistance in Europe.

plant biology↗