Phylogenetic relationships of graminicolous downy mildews based on cox2 sequence data

• Published in: Mycological research Vol. 112; no. 3; pp. 345 - 351
• Main Authors: Thines, Marco, Göker, Markus, Telle, Sabine, Ryley, Malcolm, Mathur, Kusum, Narayana, Yaladabagi D., Spring, Otmar, Thakur, Ram P.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-03-2008
• Subjects: Algal Proteins - chemistry; Algal Proteins - genetics; Base Sequence; corn; Cyclooxygenase 2 - chemistry; Cyclooxygenase 2 - genetics; downy mildew; genetic relationships; grain sorghum; Molecular Sequence Data; molecular systematics; Oomycetes; Pennisetum glaucum; Peronosclerospora; Peronospora - classification; Peronospora - genetics; Peronosporaceae; Peronosporaceae phylogeny; Peronosporales; Peronosporomycetes; Phylogeny; Phytophthora; Plant Diseases - microbiology; plant pathogenic fungi; prostaglandin synthase; Sarga; Sclerophthora; Sclerospora; Sequence Alignment; sequence analysis; Sequence Analysis, DNA; Sorghum bicolor; Sorghum bicolour; Zea mays; Sarga; Sorghum bicolour; Zea mays; Peronosporaceae phylogeny; Pennisetum glaucum
• ISSN: 0953-7562; 1469-8102
• DOI: 10.1016/j.mycres.2007.10.010

Graminicolous downy mildews (GDM) are an understudied, yet economically important, group of plant pathogens, which are one of the major constraints to poaceous crops in the tropics and subtropics. Here we present a first molecular phylogeny based on
cox2 sequences comprising all genera of the GDM currently accepted, with both lasting (
Graminivora,
Poakatesthia, and
Viennotia) and evanescent (
Peronosclerospora,
Sclerophthora, and
Sclerospora) sporangiophores. In addition, all other downy mildew genera currently accepted, as well as a representative sample of other oomycete taxa, have been included. It was shown that all genera of the GDM have had a long, independent evolutionary history, and that the delineation between
Peronosclerospora and
Sclerospora is correct.
Sclerophthora was found to be a particularly divergent taxon nested within a paraphyletic
Phytophthora, but without support. The results confirm that the placement of
Peronosclerospora and
Sclerospora in the
Saprolegniomycetidae is incorrect.
Sclerophthora is not closely related to
Pachymetra of the family
Verrucalvaceae, and also does not belong to the
Saprolegniomycetidae, but shows close affinities to the
Peronosporaceae. In addition, all GDM are interspersed throughout the
Peronosporaceae s lat., suggesting that a separate family for the
Sclerosporaceae might not be justified.