Figure 1.
Maximum Likelihood phylogenetic tree based on mitochondrial cox 1 sequences of Phytophthora ×stagnum and representative species.
Alignment was conducted with MAFFT version 7. Phylogenetic tree was generated in MEGA5. GenBank accession numbers of sequences are given following the species names and isolate codes. Bootstrap values are shown on branches (1,000 replicates; values <50% are not shown).
Figure 2.
Internal transcribed spacer (ITS) sequence alignment of Phytophthora ×stagnum, P. mississippiae and P. taxon PgChlamydo.
Position numbers are given based on the alignment. Yellow indicates sequences belong to P. taxon PgChlamydo authentic isolates. Blue indicates sequences belong to P. mississippiae type isolate 57J3. aPosition 15 is in the poly(A) region of ITS 1, which may contain sequencing errors. Thus, it is excluded from the analysis of hybridization. However, the indel of position 15 among three types of P. ×stagnum clones explains continual polymorphism and unreadable sequences of the ITS 1 regions amplified with the forward primer ITS6F in the initial sequencing before cloning. bType 1 and 2 occurred 21 and 10 times among 31 clones producing 816-bp sequences.
Figure 3.
Beta-tubulin sequence alignment of Phytophthora ×stagnum, P. mississippiae and P. taxon PgChlamydo.
Position numbers are given based on the alignment. Shading color: green indicates ambiguous sequences of polymorphic positions; yellow indicates sequences of the paternal parent P. taxon PgChlamydo; blue indicates sequences of the putative maternal parent. aY = T and C; S = G and C; M = A and C; R = G and A.
Figure 4.
Colony morphology of Phytophthora ×stagnum representative isolates on various media incubated at 20°C for 10 days in the dark.
CA = carrot agar, CV8A = 20% clarified V8 juice agar, MEA = malt extract agar, PDA = potato dextrose agar.
Figure 5.
Average daily radial growth of Phytophthora ×stagnum representative isolates in carrot agar (CA) and 20% clarified V8 juice agar (CV8A) over an 8-days period.
Figure 6.
Morphology of Phytophthora ×stagnum.
(a–g) Nonpapillate and noncaducous sporangia in various shapes; (a, b) Ovoid sporangia; (c, d) Ovoid to ellipsoid sporangia; (e, f) Obpyriform sporangia; (g) A germinated sporangium in distorted shape; (h) Direct germination of an obpyriform sporangium; (i) A sporangium releasing zoospores; (j) Nested internal proliferation; (k) Extended internal proliferation; (l) Hyphal swellings; (m) Catenulate hyphal swellings; (n) Thin-walled intercalary chlamydospores and hyphal swellings; (o) A thin-walled intercalary chlamydospore; (p) A thick-walled chlamydospore; (q–t) Ornamented, aborted oogonia produced by isolates 36H8 and 36J7; (q) An oogonium with an amphigynous antheridium; (r–t) Ornamented oogonia with distorted antheridia; (u, v) Relatively smooth-walled, darkly pigmented oogonia produced by isolates 43F3 and 44F9; (u) An oogonium containing a plerotic oospore with a globose antheridium; (v) Oogonia with abortive oospores. Bars = 10 µm.