Diversity and fitness of Plasmopara viticola isolates resistant to QoI fungicides

Corio‐Costet, Marie‐France; Dufour, Marie‐Cécile; Cigna, Jérémy; Abadie, Pierre; Chen, Wei‐Jen

doi:10.1007/s10658-010-9711-0

Cited by 58 publications

(32 citation statements)

References 21 publications

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“…But these findings could result from other factors, including immigration of sensitive isolates, selection for other traits linked to resistance mutations or genetic drift [44]. Though relatively few carefully controlled experiments have been conducted, the majority indicate that fitness costs associated with fungicide resistance are either low (for example, [8,32]) or absent (for example, [14,45]). But in some cases fitness costs were found to be substantial (for example, [26,31,25,55]) both in laboratory measurements and in field experiments.…”

Section: Discussionmentioning

confidence: 99%

Can High-Risk Fungicides be Used in Mixtures Without Selecting for Fungicide Resistance?

Mikaberidze¹,

McDonald²,

Bonhoeffer³

2014

Phytopathology®

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Fungicide mixtures produced by the agrochemical industry often contain low-risk fungicides, to which fungal pathogens are fully sensitive, together with high-risk fungicides known to be prone to fungicide resistance. Can these mixtures provide adequate disease control while minimizing the risk for the development of resistance? We present a population dynamics model to address this question. We found that the fitness cost of resistance is a crucial parameter to determine the outcome of competition between the sensitive and resistant pathogen strains and to assess the usefulness of a mixture. If fitness costs are absent, then the use of the high-risk fungicide in a mixture selects for resistance and the fungicide eventually becomes nonfunctional. If there is a cost of resistance, then an optimal ratio of fungicides in the mixture can be found, at which selection for resistance is expected to vanish and the level of disease control can be optimized.

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Section: Discussionmentioning

confidence: 99%

Can High-Risk Fungicides be Used in Mixtures Without Selecting for Fungicide Resistance?

Mikaberidze¹,

McDonald²,

Bonhoeffer³

2014

Phytopathology®

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“…The absence of a difference in growth rate between our resistant and sensitive groups grown on untreated leaves in the laboratory suggests that the G143A mutation in cyto chrome b has no harmful effect on the growth of E. necator. How ever, the overall fitness of one population relative to another does not depend on only one fitness parameter; a combination of param- eters (growth, latent period, spore production, infection efficiency) factored into a fitness index would be more informative (9). Fitness refers to the survival and reproductive success of an allele, individ ual, or group (40), and the relative ability to survive and reproduce is critical to the persistence of resistant individuals in a population once they have been selected (34).…”

Section: Discussionmentioning

confidence: 99%

“…Although the mutation is claimed to have no effect on en zyme activity, suggesting that resistant individuals may not suffer a significant fitness penalty (1,6,9,26,29,33,34), Qol resistance can compromise fitness in some pathogens (15,17,18,25,35,46,50). Only a few studies have been presented on the fitness of labora tory-induced Qol-resistant mutants or of field isolates of fungal pathogens (9,18,29,35,46). Fitness can be defined as the survival and reproductive success of an allele, individual, or group (40).…”

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confidence: 99%

“…On the other hand, if there is no significant fitness penalty, anti-resistance strategies such as alternating fungicides from groups with different modes of action may only serve to delay resistance development (19), and once practical resistance devel ops, the fungicide has lost efficacy. Conflicting reports on the fit ness of Qol-resistant pathogens (9,25,46) indicate that this may be species-specific, dictated in part by the pathogen's genetic back ground and conditions of disease development.…”

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confidence: 99%

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Fitness ofErysiphe necatorwith G143A-Based Resistance to Quinone Outside Inhibitors

et al. 2014

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Rallos, L. E. E., Johnson, N. G., Schmale, D. G., Ill, Prussin, A. J., II, and Baudoin, A. B. 2014. Fitness of Erysiphe necator with G143A-based resistance to quinone outside inhibitors. Plant Dis. 98:1494-1502.Management of grape powdery mildew (Erysiphe necator) using qui none outside inhibitors (Qols) has eroded in an increasing number of regions due to resistance development. To determine persistence of re sistance when Qols are withdrawn, competition assays were conducted on unsprayed grape plants (Vitis vinifera 'Chardonnay') by cycling mixtures of resistant and sensitive isolates characterized as genetically diverse based on microsatellite analyses. Under laboratory conditions, %G143A, quantified by quantitative polymerase chain reaction (qPCR), increased significantly, indicating competitiveness of the resistant fraction. To confirm competitiveness in the field, trials using potted plants were conducted. Percent G143A tended to decrease in one growing season, probably due to spore migration and mixing of populations with natural background inoculum. In a second season, Qol resistance persisted at high frequency for 4 weeks. Resistant popu lations were also found to persist in one vineyard without Qol applica tion for four consecutive years. The frequency was still about 25% in the fourth year, with higher frequency (36%) in a hotspot section. Qolresistant populations with >5% G143A also harbored Y136F in the cyp51 gene that confers some resistance to sterol demethylation inhibi tors, another fungicide class for powdery mildew control. Double re sistance could have been partly responsible for persistence of Qol resistance at this location.

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“…Despite this importance, the grape productivity, and consequently the wine industry, is largely vulnerable to a large number of pests and diseases, including viruses, bacteria, arthropods, birds and fungi (Delaunois et al, 2014). To combat these pests, most wine producers worldwide rely heavily on chemical treatments (pesticides), and particularly fungicides (Delaunois et al, 2014), which can be sprayed more than 10 times per year (Corio-Costet et al, 2011). Some studies estimate that some French vineyards possibly receive up to 93 000 tons of fungicide per year (Viel et al, 1998;Niccolucci et al, 2008), to control losses in productivity and wine quality due to fungi (Hocking et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Effects of native biodiversity on grape loss of four castes: testing the biotic resistance hypothesis

et al. 2018

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Abstract. Management of agricultural landscapes can influence the biodiversity and the ecological services provided by these ecosystems, such as natural biological pest control. Viticulture is a very important economic activity in most countries with Mediterranean climate, often shaping their landscapes and culture. Grape production is affected by a number of pests and diseases, and farmers use prophylactic and response-driven pesticides to control these pests. Here we quantified the main biotic causes of crop losses in four grape castes, two red (Touriga Nacional and Baga) and two white (Arinto and Chardonnay), and evaluated the potential effect of native biodiversity to provide biotic resistance to pest outbreaks and grape losses. Specifically, the diversity and abundance of bird and insect communities in these vineyards were quantified and divided into functional guilds (pest, neutral or auxiliary), to test whether these natural communities hold the potential to naturally control grape pests (biotic resistance hypothesis) under normal vineyard management (including pesticide application regimes). A potential association between distance to the vineyard edge and grape losses was also evaluated. We recorded a very small proportion of grape losses (mean = 0.6 %; max = 7.5 %), with insect pests showing a preference for the castes Baga (red) and Chardonnay (white), while bird pests avoided the caste Arinto (white). Grape color did not influence losses caused by insect pests, but birds showed a preference for red castes. The caste Baga was also more vulnerable to losses caused by fungi. Despite their low impact on grape production, most insects and birds detected in the six vineyards were pests, which entails a potentially low level of biotic resistance in this highly managed agricultural ecosystem. Further research is necessary to fully evaluate the role of functional biodiversity in vineyards, particularly if alternative production processes, such as organic farming, can increase the potential of native biodiversity to protect against grape losses from pests under lower regimes of chemical spraying.

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Diversity and fitness of Plasmopara viticola isolates resistant to QoI fungicides

Abstract: The effectiveness of Quinone outside Inhibitor (QoI) fungicides against grape downy mildew in European vineyards has significantly decreased in the last decade.

Cited by 58 publications

References 21 publications

Can High-Risk Fungicides be Used in Mixtures Without Selecting for Fungicide Resistance?

Can High-Risk Fungicides be Used in Mixtures Without Selecting for Fungicide Resistance?

Fitness ofErysiphe necatorwith G143A-Based Resistance to Quinone Outside Inhibitors

Effects of native biodiversity on grape loss of four castes: testing the biotic resistance hypothesis

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