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Twenty-seven isolates of Phytophthora infestans collected in Hungary in 2001 were tested for mating type, response to metalaxyl, isozyme geno­type at glucose-6-phosphate isomerase (Gpi) and peptidase A (Pep) loci and nuclear DNA fingerprints with probe RG57. The ratios of the mating types A1 to A2 were 5:6 and 9:7 among isolates from potato and tomato, respectively. Seventeen isolates were sensitive to metalaxyl, 1 isolate responded intermediately and 9 isolates were resistant. No novel combi­nations of isozyme alleles were found; all isolates were Gpi 100/100, and genotypes at the Pep locus were 96/96 (63%), 83/96 (11%) and 100/100 (26%). In contrast, all of the 22 RG57 fingerprints exhibited patterns that have not been reported in Hungary before. On the basis of combined traits, 22 multilocus genotypes, unnoted elsewhere in Europe, were con­struct­ed among the 27 isolates analysed. These results indicate that varia­bi­lity in the Hungarian P. infestans populations is likely due to local events (asexual and sexual interactions) rather than migration from other countries.

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A total of 123 isolates of Phytophthora infestans were recovered from 43 commercial fields and allotments of potato and tomato in Hungary. Isolates were characterised for mating type, response to metalaxyl, isozyme genotype at glucose-6-phosphate isomerase (Gpi) and peptidase A (Pep) loci, nuclear DNA fingerprint with probe RG57 and mitochondrial haplotype. Both mating types were detected in 8 potato and 3 tomato fields. The frequency of A1 and A2 were 47.5% and 52.5% on potato and 60.5% and 39.5% on tomato. More than sixty per cent of the whole population were resistant (31.1%) or responded intermediately (30.2%) to the fungicide metalaxyl in vitro. All isolates were monomorphic at the Gpi locus (100/100), but four allele combinations 100/100 (33%), 96/100 (28%), 96/96 (31%) and 83/96 (8%) were found at the Pep locus. Genotype Pep 83/96 is rare in Europe and all isolates with this allele combination were of A1 mating type and Ia mitochondrial haplotype. As in other European populations, only two of the four mitochondrial haplotypes (Ia, 32.5% and IIa, 67.5%) were detected. Diversity of RG57 fingerprints was high. Of the 79 different fingerprints found 67 were not detected previously.

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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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population structure using multilocus genotype data: Linked loci and correlated allele frequencies. Genetics 164 :1567–1587. Pritchard J.K. Inference of population structure using

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Falush , D. , Stephens , M. and Pritchard , J. K. ( 2007 ): Inference of population structure using multilocus genotype data: dominant markers and null alleles . — Mol. Ecol. Notes 7 : 574 – 578 . https://doi.org/10.1111/j.1471-8286.2007.01758.x

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Cereal Research Communications
Authors: L. Brbaklić, D. Trkulja, A. Kondić-Špika, S. Mikić, M. Tomičić and B. Kobiljski

genotype data. Genetics 155 :945–959. Donnelly P. Inference of population structure using multilocus genotype data Genetics 2000

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Acta Veterinaria Hungarica
Authors: Radoslav Židek, Daniela Jakabová, Jozef Trandžík, Ján Buleca, František Jakab, Peter Massányi and László Zöldág

536 539 Rannala, B. and Mountain, J. (1997): Detecting immigration by using multilocus genotypes. Proc. Natl. Acad. Sci. USA 94 , 9197

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862 872 Pritchard, J.K., Stephens, M., Donnelly, P. 2000. Inference of population structure using multilocus genotype data. Genetics 155 :945

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234 40 O’Donnell, K., Ward, T.J., Aberra, D., Kistler, H.C., Aoki, T., Orwig, N., Kimura, M., Bjørnstad, Å., Klemsdal, S.S. 2008. Multilocus genotyping and molecular

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Falush , D. , Stephens , M. and Pritchard , J. K. ( 2007 ): Inference of population structure using multilocus genotype data: dominant markers and null alleles. – Mol. Ecol. Notes 7 ( 4 ): 574 – 578 . https://doi.org/10.1111/j.1471

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