Using dynamic diversity to achieve durable disease resistance in agricultural ecosystems

McDonald, Bruce A.

doi:10.1590/s1982-56762014000300001

Cited by 60 publications

(50 citation statements)

References 22 publications

(19 reference statements)

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“…The findings described above strongly support the hypothesis that fungal virulence can evolve quickly in agricultural systems (McDonald 2014). Major gene resistance coupled with genetic uniformity of crop plants provides strong selection pressure for pathogen populations to overcome disease resistance, as described above for blackleg resistance of canola.…”

Section: Evolution Of Virulence In Fungal Plant Pathogenssupporting

confidence: 75%

Evolution of virulence in fungal plant pathogens: exploiting fungal genomics to control plant disease

2015

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The propensity of a fungal pathogen to evolve virulence depends on features of its biology (e.g. mode of reproduction) and of its genome (e.g. amount of repetitive DNA). Populations of Leptosphaeria maculans, a pathogen of Brassica napus (canola), can evolve and overcome disease resistance bred into canola within three years of commercial release of a cultivar. Avirulence effector genes are key fungal genes that are complementary to resistance genes. In L. maculans these genes are embedded within inactivated transposable elements in genomic regions where they are readily mutated or deleted. The risk of resistance breakdown in the field can be minimised by monitoring disease severity of canola cultivars and virulence of fungal populations using high throughput molecular assays and by sowing canola cultivars with different resistance genes in subsequent years. This strategy has been exploited to avert yield losses due to blackleg disease in Australia.

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Section: Evolution Of Virulence In Fungal Plant Pathogenssupporting

confidence: 75%

Evolution of virulence in fungal plant pathogens: exploiting fungal genomics to control plant disease

2015

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“…annually or every few years) in order to impose disruptive selection on populations of crop pathogens and force them to make trade-offs among traits ( figure 1). This 'dynamic diversity' can be implemented in many ways [67][68][69][70], including improved deployment strategies for resistance genes and resistant cultivars, more frequent turnover of crop varieties that carry different resistance genes, improved deployment strategies for fungicides, more frequent crop rotations that include more species, smaller fields planted to individual crops and growing greater numbers of crop species per unit area under cultivation. The overall objective is to break up the adaptive landscape into smaller units that change on a regular basis to present the corresponding populations of crop pathogens with evolutionary dilemmas that lead to disruptive selection (figure 1).…”

Section: Example 4: Rapid Global Dissemination Of New Clones Carryingmentioning

confidence: 99%

Rapid emergence of pathogens in agro-ecosystems: global threats to agricultural sustainability and food security

McDonald

Stukenbrock

2016

Phil. Trans. R. Soc. B

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273

199

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Agricultural ecosystems are composed of genetically depauperate populations of crop plants grown at a high density and over large spatial scales, with the regional composition of crop species changing little from year to year. These environments are highly conducive for the emergence and dissemination of pathogens. The uniform host populations facilitate the specialization of pathogens to particular crop cultivars and allow the build-up of large population sizes. Population genetic and genomic studies have shed light on the evolutionary mechanisms underlying speciation processes, adaptive evolution and long-distance dispersal of highly damaging pathogens in agro-ecosystems. These studies document the speed with which pathogens evolve to overcome crop resistance genes and pesticides. They also show that crop pathogens can be disseminated very quickly across and among continents through human activities. In this review, we discuss how the peculiar architecture of agro-ecosystems facilitates pathogen emergence, evolution and dispersal. We present four example pathosystems that illustrate both pathogen specialization and pathogen speciation, including different time frames for emergence and different mechanisms underlying the emergence process. Lastly, we argue for a re-design of agro-ecosystems that embraces the concept of dynamic diversity to improve their resilience to pathogens. This article is part of the themed issue ‘Tackling emerging fungal threats to animal health, food security and ecosystem resilience’.

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“…They have promoted the discovery of new resistance genes and strongly facilitate their combination in single variety, by genomic selection (e.g., Heffner et al, 2009; Tester and Langridge, 2010). In the future, biotechnologies will allow creating genetically modified new variety with resistance alleles to which the pathogen has never been exposed (McDonald, 2014; Wulff and Moscou, 2014; Figueroa et al, 2016). We could therefore imagine that the deployment of resistance genes into new cultivars will be informed by the knowledge of population genetics of the corresponding avirulence genes and by the dynamics of these virulences in field pathogen populations (Wulff and Moscou, 2014; Figueroa et al, 2016).…”

Section: Pyramiding Disease Resistance Genes To Enhance Their Durabilmentioning

confidence: 99%

Combining Selective Pressures to Enhance the Durability of Disease Resistance Genes

Delmotte¹,

Bourguet²,

Franck

et al. 2016

Front. Plant Sci.

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The efficacy of disease resistance genes in plants decreases over time because of the selection of virulent pathogen genotypes. A key goal of crop protection programs is to increase the durability of the resistance conferred by these genes. The spatial and temporal deployment of plant disease resistance genes is considered to be a major factor determining their durability. In the literature, four principal strategies combining resistance genes over time and space have been considered to delay the evolution of virulent pathogen genotypes. We reviewed this literature with the aim of determining which deployment strategy results in the greatest durability of resistance genes. Although theoretical and empirical studies comparing deployment strategies of more than one resistance gene are very scarce, they suggest that the overall durability of disease resistance genes can be increased by combining their presence in the same plant (pyramiding). Retrospective analyses of field monitoring data also suggest that the pyramiding of disease resistance genes within a plant is the most durable strategy. By extension, we suggest that the combination of disease resistance genes with other practices for pathogen control (pesticides, farming practices) may be a relevant management strategy to slow down the evolution of virulent pathogen genotypes.

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Using dynamic diversity to achieve durable disease resistance in agricultural ecosystems

Cited by 60 publications

References 22 publications

Evolution of virulence in fungal plant pathogens: exploiting fungal genomics to control plant disease

Evolution of virulence in fungal plant pathogens: exploiting fungal genomics to control plant disease

Rapid emergence of pathogens in agro-ecosystems: global threats to agricultural sustainability and food security

Combining Selective Pressures to Enhance the Durability of Disease Resistance Genes

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