Density-Dependent Fitness Interactions in the Bean Rust Fungus

Kardin, M. K.

doi:10.1094/phyto-79-409

Cited by 22 publications

(15 citation statements)

References 3 publications

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“…Interestingly, Leonard and Mundt () also demonstrate that small differences in latent period have greater impact on disease epidemic rates than do small differences in either infection efficiency or spore production per pustule. Further, shorter latent periods may affect competition among pathogens for host resources (Kardin and Groth ; Baart et al. ; Lehman and Shaner ; Newton et al.…”

Section: Discussionmentioning

confidence: 99%

The Jack of All Trades Is Master of None: A Pathogen's Ability to Infect a Greater Number of Host Genotypes Comes at a Cost of Delayed Reproduction

2014

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A trade-off between a pathogen's ability to infect many hosts and its reproductive capacity on each host genotype is predicted to limit the evolution of an expanded host range, yet few empirical results provide evidence for the magnitude of such trade-offs.Here, we test the hypothesis for a trade-off between the number of host genotypes that a fungal pathogen can infect (host genotype range) and its reproductive capacity on susceptible plant hosts. We used strains of the oat crown rust fungus that carried widely varying numbers of virulence (avr) alleles known to determine host genotype range. We quantified total spore production and the expression of four pathogen life-history stages: infection efficiency, time until reproduction, pustule size, and spore production per pustule. In support of the trade-off hypothesis, we found that virulence level, the number of avr alleles per pathogen strain, was correlated with significant delays in the onset of reproduction and with smaller pustule sizes. Modeling from our results, we conclude that trade-offs have the capacity to constrain the evolution of host genotype range in local populations.In contrast, long-term trends in virulence level suggest that the continued deployment of resistant host lines over wide regions of the United States has generated selection for increased host genotype range. K E Y W O R D S :Gene for gene, host range, life history, Puccinia coronata, trade-offs, virulence.

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Section: Discussionmentioning

confidence: 99%

The Jack of All Trades Is Master of None: A Pathogen's Ability to Infect a Greater Number of Host Genotypes Comes at a Cost of Delayed Reproduction

2014

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“…Sporulation is sometimes expressed in spore production per unit area of diseased leaf (Clifford & Clothier, 1974) or relative to lesion size (Miller et al , 1998). It has repeatedly been shown that spore production per lesion is highly density‐dependent (Kardin & Groth, 1989). It can be useful to consider the spore production per unit area of sporulating tissue (Hamid et al , 1982a; Subrahmanyam et al , 1983; Dowkiw et al , 2003), which is considerably less density‐dependent (Robert et al , 2004).…”

Section: Measuring Quantitative Components Of the Host–pathogen Intermentioning

confidence: 99%

“…Finally, some components of the pathogen life cycle (e.g. spore production per lesion) are strongly influenced by lesion density (Katsuya & Green, 1967; Mehta & Zadoks, 1970; Rouse et al , 1980; Kardin & Groth, 1989; Robert et al , 2004). These sources of variation are generally considered unwanted effects in aggressiveness measurements, but may account for a large portion of variability.…”

Section: Effects Of Environment On Expression Of Aggressiveness Compomentioning

confidence: 99%

“…Pathogen genotypes may respond differently to this competition effect, however, and some individuals seem to be less affected than others by lesion density (Katsuya & Green, 1967; Kardin & Groth, 1989). Katsuya & Green (1967) observed the competition between two isolates belonging to two different pathotypes of Puccinia graminis during 14 generations on wheat seedlings in a greenhouse.…”

Section: Effects Of Environment On Expression Of Aggressiveness Compomentioning

confidence: 99%

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Aggressiveness and its role in the adaptation of plant pathogens

Pariaud¹,

Ravigné²,

Halkett³

et al. 2009

Plant Pathology

267

272

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Aggressiveness, the quantitative component of pathogenicity, and its role in the adaptation of plant pathogens are still insufficiently investigated. Using mainly examples of biotrophic and necrotrophic fungal pathogens of cereals and Phytophthora infestans on potato, the empirical knowledge on the nature of aggressiveness components and their evolution in response to host and environment is reviewed. Means of measuring aggressiveness components are considered, as well as the sources of environmental variance in these traits. The adaptive potential of aggressiveness components is evaluated by reviewing evidence for their heritability, as well as for constraints on their evolution, including differential interactions between host and pathogen genotypes and trade-offs between components of pathogenicity. Adaptations of pathogen aggressiveness components to host and environment are analysed, showing that: (i) selection for aggressiveness in pathogen populations can be mediated by climatic parameters; (ii) global population changes or remarkable population structures may be explained by variation in aggressiveness; and (iii) selection for quantitative traits can influence pathogen evolution in agricultural pathosystems and can result in differential adaptation to host cultivars, sometimes leading to erosion of quantitative resistance. Possible links with concepts in evolutionary ecology are suggested.

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“…As pathogen density and genotype frequency change during the course of an epidemic, relative fitness may change over time, perhaps even reversing the fitness ranking of simple versus complex genotypes. Though experimental data are few, examples exist of both density-dependent (62,65,126,130) and frequency-dependent (65,126) selection for competing genotypes of plant pathogens. Simulation modeling suggests that density-dependent effects can slow selection for complex races in host mixtures, though density-dependence did not prevent the complex genotype from eventually dominating the simulated pathogen populations (80,81).…”

Section: Alternative Mechanismsmentioning

confidence: 99%

USE OF MULTILINE CULTIVARS AND CULTIVAR MIXTURES FOR DISEASE MANAGEMENT

Mundt

2002

Annu. Rev. Phytopathol.

586

469

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The usefulness of mixtures (multiline cultivars and cultivar mixtures) for disease management has been well demonstrated for rusts and powdery mildews of small grain crops. Such mixtures are more useful under some epidemiological conditions than under others, and experimental methodology, especially problems of scale, may be crucial in evaluating the potential efficacy of mixtures on disease. There are now examples of mixtures providing both low and high degrees of disease control for a wide range of pathosystems, including crops with large plants, and pathogens that demonstrate low host specificity, or are splash dispersed, soilborne, or insect vectored. Though most analyses of pathogen evolution in mixtures consider static costs of virulence to be the main mechanism countering selection for pathogen complexity, many other potential mechanisms need to be investigated. Agronomic and marketing considerations must be carefully evaluated when implementing mixture approaches to crop management. Practical difficulties associated with mixtures have often been overestimated, however, and mixtures will likely play an increasingly important role as we develop more sustainable agricultural systems.

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Density-Dependent Fitness Interactions in the Bean Rust Fungus

Abstract: Kardin, M. K., and Groth, J. V. 1989. Density-dependent fitness interactions in the bean rust fungus. Phytopathology 79:409-412.

Cited by 22 publications

References 3 publications

The Jack of All Trades Is Master of None: A Pathogen's Ability to Infect a Greater Number of Host Genotypes Comes at a Cost of Delayed Reproduction

The Jack of All Trades Is Master of None: A Pathogen's Ability to Infect a Greater Number of Host Genotypes Comes at a Cost of Delayed Reproduction

Aggressiveness and its role in the adaptation of plant pathogens

USE OF MULTILINE CULTIVARS AND CULTIVAR MIXTURES FOR DISEASE MANAGEMENT

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