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Phytophthora obscura sp nov., a new species of the novel Phytophthora subclade 8d

TitlePhytophthora obscura sp nov., a new species of the novel Phytophthora subclade 8d
Publication TypeJournal Article
2012
AuthorsGrünwald, NJ, Werres, S, Goss, EM, Taylor, CR, Fieland, VJ
JournalPlant Pathology
Volume61
Pagination610-622
Date PublishedJun
0032-0862
ISI:000303796900018
aesculus hippocastanum, california, clonal lineages, kalmia latifolia, oomycete, oregon, pathogen, phylogenetic-relationships, pieris, pseudosyringae, ramorum blight, rhododendron, sudden oak death, taxonomy, trees

A new Phytophthora species was detected (i) in the USA, infecting foliage of Kalmia latifolia, (ii) in substrate underneath Pieris, and (iii) in Germany in soil samples underneath Aesculus hippocastanum showing disease symptoms. The new species Phytophthora obscura sp. nov. is formally named based on phylogenetic analysis, host range, Kochs postulates and morphology. Phytophthora obscura is homothallic with paragynous antheridia and semipapillate sporangia. It is genetically closely related to P.similar to syringae and P. austrocedrae and together these three species define a new Phytophthora subclade 8d, with significant support for all genetic loci analysed including seven nuclear genes and the mitochondrial gene coxII. The morphological and ecological characteristics are very similar to P.similar to syringae, and it is likely that P.similar to obscura was not described earlier because it was identified as P.similar to syringae. Artificial inoculations indicated that horse chestnut, kalmia, pieris and rhododendron might be hosts, and Kochs postulates were confirmed for kalmia from which it was isolated. This pathogen was named after its elusive nature since it has to date rarely been detected in the US and Germany.

10.1111/j.1365-3059.2011.02538.x
Citation Key114