Pythium polare sp. nov. is a new heterothallic oomycete species isolated from fresh water and moss from various locations in both the Arctic and Antarctic. This water mould is able to infect stems and leaves of Sanionia moss (Sanionia uncinata). Pythium polare causes brown discolouration in in vitro inoculation tests at 5 °C after 5 weeks of inoculation. It is characterized by globose sporangia with various lengths of discharge tubes releasing zoospores and aplerotic oospores with usually one to five antheridia. The sexual structures are only produced in a dual culture of antheridial and oogonial isolates. Phylogenetic analysis, based on ITS sequencing, places all isolated strains of P. polare in a unique new clade, hence it is considered a novel species. Pythium canariense and Pythium violae are the most closely related species of P. polare based both on morphology and the phylogenetic analysis.
This study was supported from the Japan Society for the Promotion of Science by the grant-in-aid for scientific research Nos. 19510033, 23510032, and 23247012 (MT) the Natural Environment Research Council (NERC) via the SOFI initiative (award NE/F012705/1) (PvW), the University of Aberdeen (HvdB) and the Total Foundation (PvW, FCK).
- Bipolar distribution
- Plant pathogen
- Pythium polare
- Sanionia uncinata