부산대학교 도서관

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.mycres.2009.04.009 Byline: Adele McLeod (a), Wilhelm J. Botha (b), Julia C. Meitz (a), Chris F.J. Spies (a), Yared T. Tewoldemedhin (a), Lizel Mostert (a) Abstract: The genus Pythium is important in agriculture, since it contains many plant pathogenic species, as well as species that can promote plant growth and some that have biocontrol potential. In South Africa, very little is known about the diversity of Pythium species within agricultural soil, irrigation and hydroponic systems. Therefore, the aim of the study was to characterise a selection of 85 Pythium isolates collected in South Africa from 1991 through to 2007. The isolates were characterised morphologically as well as through sequence and phylogenetic analyses of the internal transcribed spacer regions (ITS) and the 5.8S gene of the nuclear ribosomal DNA. Phylogenetic analyses showed that the isolates represented ten of the 11 published Pythium clades [Levesque & De Cock, 2004. Molecular phylogeny and taxonomy of the genus Pythium. Mycological Research 108: 1363-1383]. Characterisation of isolates in clade D and J suggested that the phylogenetic concept of Pythium acanthicum and Pythium perplexum respectively, needs further investigation in order to enable reliable species identification within these clades. Our phylogenetic analyses of Pythium species in clade B also showed that species with globose sporangia group basal within this clade, and are not dispersed within the clade as previously reported. The 85 South African isolates represented 34 known species, of which 20 species have not been reported previously in South Africa. Additionally, three isolates (PPRI 8428, 8300 and 8418) were identified that may each represent putative new species, Pythium sp. WJB-1 to WJB-3. Author Affiliation: (a) University of Stellenbosch, Department of Plant Pathology, Private Bag X1, Matieland 7602, South Africa (b) Agricultural Research Council, Plant Protection Research Institute, Private Bag X134, Pretoria, South Africa Article History: Received 18 November 2008; Revised 5 March 2009; Accepted 21 April 2009 Article Note: (miscellaneous) Corresponding Editor: Gordon William Beakes