Analyzing the Influence of Qualitative Resistance Selection Pressure on Variation of Aggressiveness in Plasmopara Halstedii

Sakr, Nachaat; Labrouhe, Denis Tourvieille de; Walser, Pascal; Ducher, Mireille; Delmotte, François; Tourvieille, Jeanne; Vear, Félicity

doi:10.2478/v10045-011-0024-x

Cited by 10 publications

(19 citation statements)

References 12 publications

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“…These results are in accordance with our previous analysis on the behavior of FU in the growth chamber (Sakr 2009;Sakr et al 2009Sakr et al , 2011. Similarly, for P. infestans, Carlisle et al (2002) reported that the differences in aggressiveness of the different isolates of Phytophthora infestans were most easily measured on a potato variety with a high level of quantitative resistance.…”

Section: Discussionsupporting

confidence: 91%

“…Isolates of races 3xx had a shorter latent period and higher sporulation density than isolates of races 7xx. The very high percentages of infection can be explained by ideal test conditions for the parasite (Sakr 2009;Sakr et al 2009Sakr et al , 2011. All pathogen isolates caused a large reduction in seedling size except for one isolate involved in dwarfing.…”

Section: Discussionmentioning

confidence: 99%

“…High-percentage infection, short latent period, high sporulation density, and significant reduction in the length of the hypocotyl represent high aggressiveness (Sakr 2009;Sakr et al 2009Sakr et al , 2011. Analysis of five single zoosporangium isolates of each pathogen isolate showed variability for aggressiveness criteria studied within P. halstedii isolate, but not for all pathogen isolates (Table 3).…”

Section: Discussionmentioning

confidence: 99%

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Interaction between sunflower plants and five isolates ofPlasmopara halstediion the level of pathogenicity

Sakr

2012

Journal of Plant Interactions

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The interaction between sunflower plants showing a high level of quantitative resistance and five Plasmopara halstedii (the causal agent of downy mildew) isolates of several races were studied using five single zoosporangium isolates per pathogen isolate. Aggressiveness criteria were analyzed for 25 P. halstedii single zoosporangium isolates. Based on the reaction for the P. halstedii isolates to four sunflower hybrids H1ÁH4 varying only in their downy mildew resistance genes, there were differences in virulence spectrum in pathogen isolates. Analysis of five single zoosporangium isolates for P. halstedii isolates showed significant variability within pathogen isolate for all aggressiveness criteria but not for all pathogen isolates. The hypothesis explaining the interaction between P. halstedii and its host plant was discussed on the level of pathogenicity.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Interaction between sunflower plants and five isolates ofPlasmopara halstediion the level of pathogenicity

Sakr

2012

Journal of Plant Interactions

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“…After 5 years of selective pressure exerted by sunflower Pl resistance genes, six other races (300, 304, 314, 700, 704, 714) that had not been present at the start of the study, were reported (Tourvieille de Labrouhe et al, 2010;Sakr, 2011bSakr, , 2014a. Furthermore, in the absence of selection pressure, Sakr et al (2011) and Sakr (2014a) stated that P. halstedii did not evolve its virulence. This rapid evolution of virulence in P. halstedii was revealed in France, exerted by intensive Pl genes resistance selection pressure.…”

Section: Resultsmentioning

confidence: 99%

Emergence of new virulence in Plasmopara halstedii (sunflower downy mildew)

Sakr¹

2015

Acta Phytopathologica et Entomologica Hungarica

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The fast evolution of Plasmopara halstedii (downy mildew) remains a major risk for sunflower crop, as new races of the pathogen are bypassing the resistance of sunflower hybrids. In order to understand the processes which led a new virulence to appear in a local P. halstedii population, the genetic relationships were studied using 12 EST (Expressed Sequence Tag)-derived markers between five progeny isolates of races 300, 304, 314, 704 and 714 and two parental ones of races 100 and 710. All genetic analyses were carried out using five single zoosporangium isolates per P. halstedii isolate. There was no intra-isolate genetic variation among the seven pathogen isolates and five multilocus genotypes (MLG) were identified among the 35 P. halstedii single zoosporangium isolates. The single zoosporangium isolates of races 314, 704 and 714 had an intermediary genetic position between the single zoosporangium isolates of two parental isolates. The single zoosporangium isolates of three isolates of races 100, 300 and 304 were localized in the same genetic clade. Two genetic mechanisms could explain the emergence of new virulence in P. halstedii as a recombination between races and mutations in a clonal lineage.

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“…After 5 years of selective pressure exerted by sunflower Pl resistance genes, five other races (300, 304, 314, 704 and 714) that had not been present at the start of the study, were reported (Tourvieille de Labrouhe et al, 2010;Sakr, 2014aSakr, , 2014bSakr, , 2014e, 2015b. Furthermore, in the absence of selection pressure, Sakr et al (2011) and Sakr (2014b) stated that P. halstedii did not evolve its virulence. This rapid evolution of virulence in P. halstedii was revealed in France, exerted by intensive Pl genes resistance selection pressure.…”

Section: Discussionmentioning

confidence: 99%

Evolution of Two Components of Pathogenicity in Plasmopara halstedii (Downy Mildew) under Sunflower Qualitative Resistance Selection Pressure

Sakr¹

2016

Acta Phytopathologica et Entomologica Hungarica

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Evolution of pathogenicity, morphological, and genetic traits were analyzed in a local Plasmopara halstedii (downy mildew) population (including two parental and five progeny isolates) multiplied under sunflower qualitative resistance selection pressure for five years. The two components of pathogenicity developed in response to Pl resistance genes selection pressure. The emergence of new virulence in P. halstedii progeny isolates carrying several levels of aggressiveness was an important consequence of selection pressure. However, appearance of new virulence did get along with evolution of aggressiveness in progeny isolates as compared with parental ones. For progeny P. halstedii isolates, an increase in pathogen virulence had direct consequences on its aggressiveness. There was no influence of selection pressure on morphological traits, but an effect was observed on evolution of genetic architecture. However, arrangement of genetic traits did get along with evolution of pathogenicity. It is clear that qualitative resistance selection pressure plays an important role in the evolution of sunflower downy mildew population.

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Analyzing the Influence of Qualitative Resistance Selection Pressure on Variation of Aggressiveness in Plasmopara Halstedii

Cited by 10 publications

References 12 publications

Interaction between sunflower plants and five isolates ofPlasmopara halstediion the level of pathogenicity

Interaction between sunflower plants and five isolates ofPlasmopara halstediion the level of pathogenicity

Emergence of new virulence in Plasmopara halstedii (sunflower downy mildew)

Evolution of Two Components of Pathogenicity in Plasmopara halstedii (Downy Mildew) under Sunflower Qualitative Resistance Selection Pressure

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