Characterization of a Plasmopara species on Ambrosia artemisiifolia, and notes on P. halstedii, based on morphology and multiple gene phylogenies

Young Joon Choi, Levente Kiss, László Vajna, Hyeon Dong Shin

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)


Common ragweed (Ambrosia artemisiifolia) is an invasive and highly allergenic plant species, on which two species, Plasmopara halstedii and Plasmopara angustiterminalis, have been recognized to cause downy mildew disease. In this study, morphological and molecular patterns of seven Plasmopara specimens collected from A. artemisiifolia in Canada, Hungary, and USA were compared with those of P. halstedii and P. angustiterminalis from Helianthus and Xanthium, respectively. Analyses of partial sequences of three genes, namely those for the large subunit (28S) of rDNA, cytochrome c oxidase subunit II (COX2), and NADH dehydrogenase subunit I (ND1) of mtDNA, were carried out to examine the phylogenetic relationships among these specimens using both Bayesian and maximum parsimony methods. All the phylogenetic analyses revealed that the downy mildew pathogens infecting A. artemisiifolia in Hungary and North America clearly represent a lineage distinct from other Plasmopara taxa investigated. The shape of sporangia and the width of trunks and branches also allowed the separation of the specimens parasitic to A. artemisiifolia from P. halstedii on Helianthus annuus and P. angustiterminalis on Xanthium strumarium. Surprisingly, the Hungarian and the Canadian specimens were more closely related to each other than to those from the USA based on COX2 and ND1 mtDNA data, although the D1/D2/D3 sequences of 28S rDNA were identical in all these Plasmopara specimens. The regional distribution of the mtDNA haplotypes seen in this study suggests a transatlantic migration has occurred and would be interesting to follow up with a more detailed sampling. To investigate the diversity within P. halstedii sensu lato, infecting different host plant species, specimens from six asteraceous genera, Ambrosia, Flaveria, Helianthus, Siegesbeckia, Solidago, and Xanthium, were also included in molecular analyses. These represented six distinct lineages according to the host plant genera. These findings might serve as a basis for a taxonomical reassessment of the P. halstedii complex and also for the delimitation of several well-defined species within this complex. Crown

Original languageEnglish
Pages (from-to)1127-1136
Number of pages10
JournalMycological Research
Issue number10
Publication statusPublished - 2009 Oct

Bibliographical note

Funding Information:
The authors are grateful to Dr. Cvetomir M. Denchev (SOMF) for allowing access to specimens in their care. This work was partly supported by a research grant from the Korea University to HDS in 2007. The support of a fellowship under the OECD Cooperative Research Programme: Biological Resource Management for Sustainable Agricultural Systems and that of a grant of the Hungarian Scientific Research Fund (OTKA F046841), both awarded to LK, are also acknowledged.


  • Invasive weed
  • Multigene phylogeny
  • Peronosporales
  • Pollen allergy
  • Taxonomy

ASJC Scopus subject areas

  • Biotechnology
  • Ecology, Evolution, Behavior and Systematics
  • Genetics
  • Plant Science


Dive into the research topics of 'Characterization of a Plasmopara species on Ambrosia artemisiifolia, and notes on P. halstedii, based on morphology and multiple gene phylogenies'. Together they form a unique fingerprint.

Cite this