Mycologia (2008) 100, 310-319

Eduardo Moralejo, Antonio Clemente, Enrique Descals, Lassaad Belbahri, Gautier Calmin, François Lefort, Chris F.J. Spies and Adele McLeod (2008)
Pythium recalcitrans sp. nov. revealed by multigene phylogenetic analysis
Mycologia 100 (2), 310-319
Abstract: A new species of Pythium collected from grapevine roots (Vitis vinifera) in South Africa and roots of common beet (Beta vulgaris) in Majorca, Spain, is described. The phylogenetic position of the new species was investigated by multigene sequence analyses of the internal transcribed spacers (ITS1 and ITS2) of the rDNA region, as well as three other nuclear and three mitochondrial coding genes. Maximum likelihood phylogenetic analyses based on ITS rDNA and concatenated ß-tubulin and cytrochrome c oxidase II alignment place Pythium recalcitrans together with P. sylvaticum and P. intermedium. Pythium recalcitrans sp. nov. is morphologically almost indistinguishable from other Pythium species that only form hyphal swellings in culture. However its species status is justified by the distinctiveness of the DNA sequences in all the genes examined. In culture P. recalcitrans exhibits fast radial growth, abundant spherical to subglobose hyphal swellings but produces no zoosporangia. Sexual structures are not seen in agar media but form in autoclaved grass blades floated on water. Multiple antheridia (1-7) are encountered with most of them diclinous and crook-necked. Oospores are thin-walled and either aplerotic or plerotic. P. recalcitrans was pathogenic to seedlings of Beta vulgaris and Solanum lycopersicum.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Eduardo Moralejo

Research topic(s) for pests/diseases/weeds:
identification/taxonomy

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Pythium recalcitrans	Beet/sugarbeet (Beta vulgaris)	Spain (Baleares)
	Pythium recalcitrans	Grapevine (Vitis)	South Africa