Complete issue - IMA Fungus

Runge et al.
ARTICLE
Pseudoperonospora humuli. Therefore, we feel that this
solution is to be preferred. But to introduce the new names
for the clades outlined above will necessitate a search for
characters defining synapomorphies for these groups, which
might not be easy, judging from the apparent discrepancies
between the morphological classification of Waterhouse
(1963), and recent phylogenetic studies (Cooke et al. 2000,
Kroon et al. 2004, Blair et al. 2008). Probably, these genera
might have to be defined with the aid on DNA sequence
synapomorphies, rather than only morphology. But retaining
the usage of the generic name Phytophthora for all the at
least six monophyletic groups between Halophytophthora
and at the same time retaining the 19 downy mildew genera,
would not only be contrary to the widely accepted idea of
ideally having monophyletic taxa only, but also hamper the
awareness of the unique evolution of these organisms,
stepwise towards obligate biotrophy (Thines & Kamoun
2010). For example, in terms of evolution, Phytophthora
infestans is much closer to downy mildews than to P. sojae or
even P. ramorum. But for the understanding of the evolution
of obligate biotrophy, which is one of the most fascinating
and fundamental evolutionary tipping points for any group of
pathogens, it will be even more important to obtain genome
sequences for members of the clades 4.1 and 4.2, which
are apparently the closest relatives of the downy mildews,
and of the neglected species of Phytophthora affecting
Cyperaceae.
Acknowledgements
Fabian Runge is supported by a fellowship of the Ministry of Science
and Education of Baden-Württemberg. This study was supported
by the research funding programme “LOEWE – Landes-Offensive
zur Entwicklung Wissenschaftlich-ökonomischer Exzellenz” of the
Ministry of Higher Education, Research, and the Arts of Hesse. Work
in the laboratory of BD was supported by a Michigan State University
GREEEN grant (GR10-021)
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