infestans strain. Mao and Tyler (1991) characterized the size and the general organization of the P. sojae genome. During the 1990’s, transformative molecular
biology technologies, especially BGB324 ic50 the polymerase chain reaction (Mullis and Faloona 1987), became more widespread in oomycete research and were the basis for a broad range of applications. Molecular phylogeny With universal primers developed for fungi that also worked for oomycetes (White et al. 1990) and a significant number of rDNA sequences available for designing more primers it was possible to generate sequences for rDNA for a wide range of genera within the oomycetes. Briard et al. (1995) generated partial sequences of the large nuclear ribosomal subunit (LSU) for some of Pythium and Phytophthora species. Dick et al. (1999) sequenced the complete SSU from eight different
genera of oomycetes. Riethmüller et al. (1999) sequenced the D1 and part of the D2 region of LSU for close to 50 species in several oomycete genera, Petersen and Rosendahl (2000) did 24 species among five orders with the same sequence region whereas Leclerc et al. (2000) looked at LSU and ITS in a study on Saprolegniaceae. Hudspeth et al. (2000) performed partial sequencing of the mitochondrial cytochrome oxydase 2 gene that included 15 genera of Oomycetes. As was mentioned above, the concept of a monophyletic group for the oomycetes clearly separated from the true Fungi had emerged and these studies supported the monophyly of oomycetes. Sparrow (1976) proposed the concept of two galaxies within the Luminespib mouse oomycetes which was formalized by Dick (2001) as the subclasses Saprolegniomycetidae and Peronosporomycetidae. An important advance in oomycete phylogenetics was to demonstrate that DOCK10 Eurychasma is the most basal clade identified to date (Sekimoto et al. 2008a; Kuepper et al. 2006). The evolutionary origin of the oomycetes is currently believed to be in the sea as obligate parasites with saprophytism
on land as the derived state (Beakes et al. 2011). The peronosporalean galaxy appears to be monophyletic with the limited number of markers we have so far whereas the saprolegnian galaxy is no longer considered monophyletic once the additional more basal taxa were included (Beakes et al. 2011). In the oomycetes, there have been very comprehensive phylogenies done at the genus level. Lee and Taylor (1992) generated a phylogeny for five Phytophthora species based on ITS whereas Cooke et al. (2000) produced a phylogeny for all the Phytophthora species known at the time. Lévesque and de Cock (2004) completed an equivalent study with all available Pythium species. Multigene phylogenies with very comprehensive sets of species were also completed for Phytophthora (Blair et al. 2008; Kroon et al. 2004).