Submitted to: Mycologia
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/28/2004
Publication Date: 7/1/2004
Citation: Allain-Boule, N., Tweddell, R., Mazzola, M., Belanger, R., Levesque, C. 2004.Pythium attrantheridium sp. nov.-taxonomy and comparison with related species. Mycologia. 108:795-805. Interpretive Summary: Fungi belonging to the genus Pythium form diverse asociations with plants. Sometimes these associations result in damage to plants resulting from infection of the host root system. Pythium spp. have been implicated as incitants of replant disease which is characterized by the poor growth and even death of new trees established on sites that were previously planted to apple. In studies conducted to determine the species of Pythium present in orchard soils, a number of new, previously undescribed species, were recovered. In this paper, we provide a detailed description of one new species of Pythium based on its morphological, biological and molecular characteristics. This new species has been designated Pythium attrantheridium.
Technical Abstract: Numerous species of Pythium form diverse associations with their plant hosts. However, the species and interactions between members of this genus and apples have received scant attention. Pythium attrantheridium is a new species isolated from cavity spot lesions of carrots and cherry seedlings, in addition to apple. This fungus is closely related to the heterothallic P. intermedium but is distinguishable by some molecular characteristics, morphological characteristics, ad mating incompatibility with P. intermedium. The internal transcribed spacer (ITS) region of the nuclear ribosomal DNA of all strains of P. attrantheridium is different from that of all other known Pythium spp. The oogonia attract a large number of antheridia when compatible mating types contact each other. The positive mating type produces zoospores unlike those of P. intermedium. Thus, biological, morphological and molecular data support the recognition of a new species.