Pathogenic, morphological and genetic diversity in Plasmopara halstedii, the causal agent of sunflower downy mildew

Sakr, Nachaat

doi:10.4025/actasciagron.v35i1.15722

Cited by 3 publications

(7 citation statements)

References 30 publications

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“…These isolates belong to several races and may be found to be an effect of additional avirulence genes in P. halstedii isolates as observed for another oomycete P. infestans (Montarry et al, 2010). Second, isolates belong to 7xx races that accumulate a large number of avirulence genes and show the lowest levels of aggressiveness, compared with isolates belong to 100 and 3xx races that accumulate a small number of avirulence genes and show the highest levels of aggressiveness (Sakr, 2012(Sakr, , 2013(Sakr, , 2014a(Sakr, , 2014b(Sakr, , 2014d(Sakr, , 2014e, 2015b. For progeny isolates, appearance of the highest virulent isolates of 7xx races compared with the least virulent isolates of 3xx races in response to Pl genes resistance selection pressure is costly due to trade-offs with aggressiveness.…”

Section: Discussionmentioning

confidence: 99%

“…Fourteen different races of this pathogen have now been characterized, nine of which emerged in the last ten years (Delmotte et al, 2008;Sakr, 2014b). High percentage infection, short-latent period, high sporulation density, and significant reduction in the length of the hypocotyl represent high aggressiveness (Sakr, 2012(Sakr, , 2013(Sakr, , 2014a(Sakr, , 2014b(Sakr, , 2014c(Sakr, , 2014d(Sakr, , 2014e, 2015a. Single zoosporangium isolates of parental isolate 100 and progeny isolates of races 300, 304 and 314 were more aggressiveness that single zoosporangium isolates of parental isolate 710 and progeny isolates of races 704 and 714 (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Characterization of the highest and the least virulent P. halstedii races of could be assessed in response to Pl2 resistance gene in sunflower differential line D3 (Sakr, 2012(Sakr, , 2013(Sakr, , 2014a(Sakr, , 2014b. Based on the virulence reaction for the seven P. halstedii pathotypes to D3, we can divide them into two groups.…”

Section: Characterization Of Virulence For P Halstedii Parental and mentioning

confidence: 99%

“…To characterize aggressiveness criteria: percentage infection, latent period, sporulation density and reduction of hypocotyl length for 35 P. halstedii single zoosporangium isolates (Sakr, 2012(Sakr, , 2013(Sakr, , 2014a(Sakr, , 2014b(Sakr, , 2014c(Sakr, , 2014d(Sakr, , 2014e, 2015a, one INRA inbred line ʻFUʼ was used. It carried no Pl gene, but is known to a have high level of quantitative resistance (Tourvieille de Labrouhe et al, 2008).…”

Section: Measurement Of Aggressiveness In P Halstedii Single Zoospormentioning

confidence: 99%

“…halstedii is characterized by a high level of evolutionary potential expressed by high virulence, aggressiveness and a great potential in developing new races (Delmotte et al, 2008;Tourvieille de Labrouhe et al, 2010;Ahmed et al, 2012;Sakr, 2012Sakr, , 2013Sakr, , 2014aSakr, , 2014bSakr, , 2014cSakr, , 2014dSakr, , 2014e, 2015aSakr, , 2015b. Even thought some studies aimed to analyze the influence of qualitative sunflower selection pressure on virulence in both experimental and filed conditions (Delmotte et al, 2008;Tourvieille de Labrouhe et al, 2010;Ahmed et al, 2012;Sakr, 2014aSakr, , 2014bSakr, , 2014e, 2015b, a number of questions regarding its influence on evolution of aggressiveness (Sakr, 2014b, morphological (Sakr, 2014c), and genetic characteristics (Sakr, 2012(Sakr, , 2013(Sakr, , 2014d(Sakr, , 2014e, 2015a(Sakr, , 2015b have still remained unanswered. In this study, phenotypic analyses (morphological and pathogenic) and genetic characteristics were analysed for seven P. halstedii pathotypes: race 100 present in France since the 1966, race 710 introduced from the USA during the 1980s (Tourvieille de Labrouhe et al, 2000, 2010), and five progeny pathotypes of races 300, 304, 700, 704 and 714 originated from an initial mixture of pathotypes 100 and 710 (Tourvieille de Labrouhe et al, 2010;Sakr, 2014aSakr, , 2014bSakr, , 2014e, 2015b.…”

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confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Characterization Of Virulence For P Halstedii Parental and mentioning

confidence: 99%

Section: Measurement Of Aggressiveness In P Halstedii Single Zoospormentioning

confidence: 99%

mentioning

confidence: 99%

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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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Marker Development for Differentiation of Fusarium oxysporum f. sp. Niveum Race 3 from Races 1 and 2

Hudson

Waliullah

Fulton

et al. 2021

IJMS

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Fusarium wilt of watermelon, caused by Fusarium oxysporum f. sp. niveum (FON), is pathogenic only to watermelon and has become one of the main limiting factors in watermelon production internationally. Detection methods for this pathogen are limited, with few published molecular assays available to differentiate FON from other formae speciales of F. oxysporum. FON has four known races that vary in virulence but are difficult and costly to differentiate using traditional inoculation methods and only race 2 can be differentiated molecularly. In this study, genomic and chromosomal comparisons facilitated the development of a conventional polymerase chain reaction (PCR) assay that could differentiate race 3 from races 1 and 2, and by using two other published PCR markers in unison with the new marker, the three races could be differentiated. The new PCR marker, FNR3-F/FNR3-R, amplified a 511 bp region on the “pathogenicity chromosome” of the FON genome that is absent in race 3. FNR3-F/FNR3-R detected genomic DNA down to 2.0 pg/µL. This marker, along with two previously published FON markers, was successfully applied to test over 160 pathogenic FON isolates from Florida, Georgia, and South Carolina. Together, these three FON primer sets worked well for differentiating races 1, 2, and 3 of FON. For each marker, a greater proportion (60 to 90%) of molecular results agreed with the traditional bioassay method of race differentiation compared to those that did not. The new PCR marker should be useful to differentiate FON races and improve Fusarium wilt research.

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Spatial Genetic Structure and Pathogenic Race Composition at the Field Scale in the Sunflower Downy Mildew Pathogen, Plasmopara halstedii

Elameen

Labrouhe

Bret-Mestries

et al. 2022

JoF

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Yield losses in sunflower crops caused by Plasmopara halstedii can be up to 100%, depending on the cultivar susceptibility, environmental conditions, and virulence of the pathogen population. The aim of this study was to investigate the genetic and phenotypic structure of a sunflower downy mildew agent at the field scale. The genetic diversity of 250 P. halstedii isolates collected from one field in southern France was assessed using single-nucleotide polymorphisms (SNPs) and single sequence repeats (SSR). A total of 109 multilocus genotypes (MLG) were identified among the 250 isolates collected in the field. Four genotypes were repeated more than 20 times and spatially spread over the field. Estimates of genetic relationships among P. halstedii isolates using principal component analysis and a Bayesian clustering approach demonstrated that the isolates are grouped into two main genetic clusters. A high level of genetic differentiation among clusters was detected (FST = 0.35), indicating overall limited exchange between them, but our results also suggest that recombination between individuals of these groups is not rare. Genetic clusters were highly related to pathotypes, as previously described for this pathogen species. Eight different races were identified (100, 300, 304, 307, 703, 704, 707, and 714), with race 304 being predominant and present at most of the sites. The co-existence of multiple races at the field level is a new finding that could have important implications for the management of sunflower downy mildew. These data provide the first population-wide picture of the genetic structure of P. halstedii at a fine spatial scale.

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Pathogenic, morphological and genetic diversity in Plasmopara halstedii, the causal agent of sunflower downy mildew

Cited by 3 publications

References 30 publications

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

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

Marker Development for Differentiation of Fusarium oxysporum f. sp. Niveum Race 3 from Races 1 and 2

Spatial Genetic Structure and Pathogenic Race Composition at the Field Scale in the Sunflower Downy Mildew Pathogen, Plasmopara halstedii

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