Table 1.
Relevant phylogenetic studies including both Phytophthora and downy mildews.
Fig 1.
Most likely tree from a 118-taxon alignment of Phytophthora and downy mildew species.
Tree generated with 200 heuristic best tree searches using Garli 2.01. Bipartitions receiving significant support in Garli, MrBayes or PhyloBayes analyses are thickened and bipartitions receiving significant support in all three analyses are greatly thickened. Significant support was defined as bootstrap value ≥ 0.70 or posterior probability ≥ 0.95. Slashes indicate branches shortened for display purposes. The subgeneric clades of Phytophthora [12,24,25] are numbered in bold; additional clades appearing in the tree are numbered 13–16 and denoted with an asterisk. Clade 11, containing P. lilii [24] could not be included in the current study. DM, downy mildew; BDM, brassicolous DM; DMCC, DM with colored conidia; DMPH, DM with pyriform haustoria; GDM, graminicolous DM. Phytophthora strain numbers beginning with “P” refer to the World Oomycete Genetic Resource Collection. Figure created with TreeGraph2 and Inkscape.
Fig 2.
Most likely tree from 135-taxon alignment of Phytophthora and downy mildew species, excerpt.
Maximum likelihood (ML) tree, omitting outgroups and Phytophthora clades 6–10 from the figure. Thickened branches correspond to significantly supported bipartitions in both ML (Garli) and Bayesian likelihood (MrBayes); significant support was defined as bootstrap value ≥ 0.70 or posterior probability ≥ 0.95. Sporangiophore characteristics and host preferences are indicated for downy mildew taxa and P. cyperi. The length of the branch connecting the common ancestor of Eraphthora and Sclerophthora was halved for display purposes. DM, downy mildew; BDM, brassicolous DM; DMCC, DM with colored conidia; DMPH, DM with pyriform haustoria; GDM, graminicolous DM. Figure created with TreeGraph2 and Inkscape.
Fig 3.
Asexual sporulation in Phytophthora taxon mugwort strain SCVWD302.
Sporangia are non-papillate, non-caducous and variable in shape, borne in tight sympodial clusters on long stalks. The distal tips of the sporangia may swell with cytoplasm, producing ovoid to obpyriform shapes or sometimes forming a beak-like protuberance. A, ovoid sporangium; B, external proliferation with evacuated sporangium and obpyriform sporangium; C, ellipsoid sporangium with protuberance. DIC micrographs with Leica DM5000B at 1000X. Scale bar = 10 μm.
Table 2.
Summary of loci used for phylogenetic inference.
Table 3.
Downy mildew taxa included in the current study.
Fig 4.
Cladogram with proposed relationships between the genus Phytophthora, the four downy mildew groups, and outgroups.
Dotted lines indicate possible incongruence between subgeneric clades suggested by nuclear-only and mitochondrial-only trees (S2 and S3 Figs). Clade 11, containing P. lilii could not be included in the current study, but appears related to clades 6–8 [24]. Phytophthora stricta [38] appears to occupy an additional subgeneric clade. Figure created with TreeGraph2 and Inkscape.