The coelomycete Rhyzopycnis vagum D.F. Farr belong to the complex of root rot pathogens responsible for "vine decline", a serious disease o cucurbits. In Italy, the fungus has also been recently reported in association with other, unrelated hosts, such as tomato exhibiting typical corky root symptoms, as well as a root endophyte in wild, symptomless Pinus halepensis and Rosmarinus officinalis plants. Pathogenic and endophytic isolates from cucurbits, tomato, Halep pine, and rosemary from Italy and Northern and Central America were analysed for polymorphisms in single and multilocus markers. Genetic diversity indices were calculated based on ITS (ITS1-5.8S-ITS2) and Gpd (glyceraldehyde 3-phosphate dehydrogenase) haplotype and microsatellite marker frequencies. Phylogenetic and phylogeographic analysis were also made based on ITS and Gpd sequences. Genetic differentiation was found on both a geographical and a host basis, suggesting that selection may be important in the association of pathogenic and nonpathogenic R.vagum with specific hosts. Pathogenic phenotypes were identified on melon for Italian endophytic isolates under greenhouse conditions. Cryptic species were not recognised within this fungus.
Genetic and pathogenic variability of Rhizopycnis vagum D.F. FARR
TAMIETTI, Giacomo;GIRLANDA, Mariangela
2004-01-01
Abstract
The coelomycete Rhyzopycnis vagum D.F. Farr belong to the complex of root rot pathogens responsible for "vine decline", a serious disease o cucurbits. In Italy, the fungus has also been recently reported in association with other, unrelated hosts, such as tomato exhibiting typical corky root symptoms, as well as a root endophyte in wild, symptomless Pinus halepensis and Rosmarinus officinalis plants. Pathogenic and endophytic isolates from cucurbits, tomato, Halep pine, and rosemary from Italy and Northern and Central America were analysed for polymorphisms in single and multilocus markers. Genetic diversity indices were calculated based on ITS (ITS1-5.8S-ITS2) and Gpd (glyceraldehyde 3-phosphate dehydrogenase) haplotype and microsatellite marker frequencies. Phylogenetic and phylogeographic analysis were also made based on ITS and Gpd sequences. Genetic differentiation was found on both a geographical and a host basis, suggesting that selection may be important in the association of pathogenic and nonpathogenic R.vagum with specific hosts. Pathogenic phenotypes were identified on melon for Italian endophytic isolates under greenhouse conditions. Cryptic species were not recognised within this fungus.
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