Table 1.
GenBank sequences included in molecular analyses that belong to molecular operation taxonomic unit (MOUT) of Saprolegnia sp. 2 (Saprolegnia aenigmatica sp. nov) [12].
Fig 1.
Phylogenetic relationships of Saprolegnia aenigmatica sp. nov and Saprolegnia recemosa sp. nov based on ITS rDNA.
Phylogenetic tree was obtained from Bayesian inference analysis based on ITS rDNA sequences. Phylogenetic tree show the relationships among S. aenigmatica, S. racemosa and related Saprolegnia species. The numbers the branches represent the probability values (>0.95) and bootstrap support (> 75) obtained from Bayesian inference and Maximum Likelihood analyses respectively. The analyses comprise reference sequences of genus Saprolegnia [12] and all Saprolegnia isolates obtained in this study.
Table 2.
Number of ribotypes, number of sequences per ribotype, and variable positions of ITS rDNA of Saprolegnia aenigmatica sp. nov. and Saprolegnia racemosa sp. nov. Variable positions of ITS rDNA sequences for other ribotypes are indicated in lowercase.
Fig 2.
Preservation of morphological characters of Saprolegnia in absolute ethanol.
The figure shows that the specific morphological features of S. aenigmatica (a and b) and S. racemosa (c and d) maintained after 12 months in absolute ethanol: oogonia globose (Og), oogonia subglobose (Os), oogonia pyriform (Op), oogonial stalk terminal (Ot), oogonial stalk intercalary (Oi), antheridial hypha (arrow). Compared to fresh material the antheridia attached to the oogonium walls were sometimes collapsed (arrowhead), and lipid droplets in the oospore became disrupted (Ld) preserved saples in ethanol. Bar = 20 μm.
Table 3.
Summary of production of gemmae, oogonia, sporangia, zoospores and cyst of Saprolegnia aenigmatica sp. nov and Saprolegnia racemosa sp. nov. tested at selected temperatures. (+++) indicates that production was always observed, (++) indicates that production was often observed, and (+) indicates that production was rarely observed. Empty boxes indicate that no production at that temperature.
Fig 3.
Boxplots representation of morphological features of Saprolegnia aenigmatica sp. nov. and Saprolegnia racemosa sp. nov.
A linear model analysis shows that the whole set of features analyzed could differentiate S. aenigmatica (1) from S. racemosa (2) (F8,441 = 98.31, p < 0.001). The following morphological features contributed were considered: (a) sporangia length, (b) sporangia breadth, (d) oogonia length, (e) oogonia breadth, and (h) oospore diameter, while (c) cyst diameter, (f) oogonia ratio (l/b), and (g) oospore number did not contribute to differentiate Saprolegnia species.
Fig 4.
Discriminant linear function plot of morphological features of Saprolegnia aenigmatica sp. nov. and Saprolegnia racemosa sp. nov.
The morphological features (sporangia length, sporangia breadth, cyst diameter, oogonia length, oogonia breadth, oogonia ratio (l/b), oospore number and oospore diameter) per isolate were used to separate S. aenigmatica (circles) from S. racemosa (triangles). Linear dimension 1 (LD1) explained 61.5% and linear dimension 2 (LD2) explained 16.8% of variance. The percentage of correct identifications based on measurements of morphological characters was 92.38% for isolates of the S. aenigmatica and 94.17% for S. racemosa.
Table 4.
Measurements of sporangia, cysts, oogonia, and oospores, and antheridia type of Saprolegnia aenigmatica sp. nov. and Saprolegnia racemosa sp. nov.
Fig 5.
Specific morphological features of asexual and sexual structures of Saprolegnia aenigmatica sp. nov.
Light (a, b, c, d, e, f, g, and h) and electronic micrographs (i, j, and k) of: (a) sporangia clavate, terminal, with internal proliferation (arrows) and apical papilla (arrowhead) (RJBCC0020); (b) oogonia pyriform, diclinous antheridial hyphae (arrows) well developed, branched, ampullaceous (arrowhead), and centric oospores (RJBCC0028); (c) oogonial intercalary, antheridial hyphae ampullaceous (arrowhead) and centric oospores (RJBCC0038); (d) oogonia subglobose, diclinous antheridial hyphae (arrows) well developed and from variable origin, tubular (arrowhead), and centric oospores (RJBCC0039); (e) oogonia pyriform, diclinous antheridial hyphae (arrows) from variable origin, encircling the oogonia, and centric oospores that do not fill the oogonium (RJBCC0024); (f) immature oogonia moniliform, and diclinous antheridial hyphae (arrows) from variable origin (RJBCC0027); (g) oogonia moniliform, and diclinous antheridial hyphae (arrows) from variable origin, encircling the oogonia (RJBCC0026); (h) oogonia pyriform, diclinous antheridial hyphae (arrows) well developed, attached by foot-like projections (arrowhead), and centric oospores (RJBCC0039); (i) oogonia pyriform, antheridial hyphae (arrows) well developed, encircling the oogonia, and antheridial attached (arrowhead) (RJBCC0024); (j) oogonial intercalary, antheridial hyphae attached (arrowhead) (RJBCC0028); (k) antheridial hyphae (arrows) well developed, encircling the oogonia, and antheridial attached (arrowhead) (RJBCC0028). Bar = 20 μm.
Fig 6.
Specific morphological features of asexual and sexual structures of Saprolegnia racemosa sp. nov.
Light (a, b, c, d, e and g) and electronic micrographs (f and h) of: (a) sporangia clavate, terminal, with internal proliferation (arrows) and apical papilla (arrowhead) (RJBCC0003); (b) sporangia apical and apical papilla (arrowhead) (RJBCC0011); (c) oogonia globose, monoclinous antheridial hyphae (arrows) well developed and from variable origin, ampullaceous (arrowhead), and centric oospores (RJBCC0003); (d) oogonia globose, diclinous antheridial hyphae (arrows) well developed, circling the oogonia, tubular (arrowhead), and centric oospores (RJBCC0001); (e) oogonial intercalary, antheridia ampullaceous (arrows), attached by foot-like projections (arrowhead), and centric oospores (RJBCC0017); (f) oogonia globose, diclinous antheridial hyphae (arrows) well developed, and attached by foot-like projections (arrowhead) (RJBCC0001); (g) oogonia globose, grouped like racemosa structure, and centric oospores (RJBCC0002); (h) oogonia globose, grouped like racemosa structure, diclinous antheridial hyphae (arrows) well developed, and attached by foot-like projections (arrowhead) (RJBCC0002). Bar = 20 μm.