Molecular characterisation and pathogenicity of Erysiphe graminis f.sp. hordei in Australia
Tóm tắt
Pathogenicity analysis of Australian isolates of Erysiphe graminis f.sp. hordei on a set of barley lines, near-isogenic for powdery mildew resistance, and RFLP analyses of the DNA from these isolates showed only minor differences between them. The study also revealed that many ‘unnecessary genes’ for virulence have been retained. The isolates of E. graminis contained a significant quantity of dsRNA fragments, with some fragments encapsidated as virus-like particles, and a DNA plasmid homologous to a plasmid isolated previously from a European isolate. The strong homology with European genomic and plasmid DNAs, and the similarity of dsRNA, suggest that Australian isolates of E. graminis are of European origin. However, since introduction, evolution of the pathogen has diverged from that of European isolates, due to geographical isolation and lack of selection pressure from barley cultivars resistant to powdery mildew.
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