Morphological and Molecular Characterization of the Causal Agent of Downy Mildew on Quinoa (Chenopodium quinoa)

Downy mildew is an economically important and widespread disease in quinoa ( Chenopodium quinoa ) growing areas. Although in many studies Peronospora farinosa is most commonly regarded as the causal agent of the disease, identification and classification of the pathogen remain still uncertain due to...

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Bibliographic Details
Published in:Mycopathologia (1975) 2010-05, Vol.169 (5), p.403-412
Main Authors: Choi, Young-Joon, Danielsen, Solveig, Lübeck, Mette, Hong, Seung-Beom, Delhey, Rolf, Shin, Hyeon-Dong
Format: Article
Language:English
Subjects:
Biomedical and Life Sciences
Chemical properties
Chenopodium
Chenopodium quinoa
Chenopodium quinoa - microbiology
Cladistic analysis
Crop diseases
Denmark
DNA, Algal - genetics
DNA, Ribosomal Spacer - genetics
Eukaryotic Microbiology
Life Sciences
Medical Microbiology
Microbial Ecology
Microbiology
Morphology
Pathogens
Peronospora
Peronospora - classification
Peronospora - cytology
Peronospora - genetics
Phylogenetics
Phylogeny
Plant Diseases - microbiology
Plant Sciences
Quinoa
South America
Taxonomy
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Summary:Downy mildew is an economically important and widespread disease in quinoa ( Chenopodium quinoa ) growing areas. Although in many studies Peronospora farinosa is most commonly regarded as the causal agent of the disease, identification and classification of the pathogen remain still uncertain due to its taxonomic confusion. Thirty-six Peronospora isolates from quinoa with different geographic origins including Argentina, Bolivia, Denmark, Ecuador, and Peru were morphologically and molecularly compared with Peronospora species from other Chenopodium species. The morphology of three herbarium specimens was similar to that of P. variabilis , which originated from C. album , characterized by flexuous to curved ultimate branchlets and pedicellated conidia. Phylogenetic analysis based on ITS rDNA sequences also placed the quinoa pathogen within the same clade as P. variabilis . Within the ITS rDNA sequences of the quinoa pathogens, two base substitutions were found, which separated the majority of the Danish isolates from isolates from South America, but no sequence difference was found among the isolates from different cultivars of quinoa. The present results indicate that the pathogen responsible for the quinoa downy mildew is identical to Peronospora variabilis and that it should not be lumped with P. farinosa as claimed previously by most studies.
ISSN:0301-486X
1573-0832
DOI:10.1007/s11046-010-9272-y