Diaporthe helianthi is the causal agent of sunflower stem canker and it is threatening in Europe, although sporadically recorded in Italy. In a program aimed to investigate molecular variability among D.helianthi isolates from several countries, our approach was focused on the identification of extrachromosomal genetic determinants. Twenty-six isolates from different geographic origin, 14 deriving from France, 3 from ex-Yugoslavia, 3 from Argentina, 1 from Romania, 5 from Italy, have been studied. Extrachromosomal bands have been detected in most isolates. Rnase A and DNA exo-nucleases (exo-III and exo-λ) digestions suggested they were DNA plasmid-like elements apparently with a circular conformation. More detailed analysis was then performed on a selected plasmid derived from a French isolate presumably present, as inferred by molecular weight, in all French and Yugoslavian isolates (countries were the disease has a heavy incidence). Its intracellular localisation resulted to be mitochondrial. In order to check its specificity, it was used in Southern blot experiments as a probe against DNAs derived from all twenty-six D.helianthi isolates. Further investigations are needed to characterise that plasmid (cloning and sequence analysis) and to make a comparison (e.g. RFLP) with plasmids from the other D.helianthi isolates.

Identification of plasmids in Diaporthe helianthi isolates from different geographic origin

VERGARA, Mariarosaria;
2002

Abstract

Diaporthe helianthi is the causal agent of sunflower stem canker and it is threatening in Europe, although sporadically recorded in Italy. In a program aimed to investigate molecular variability among D.helianthi isolates from several countries, our approach was focused on the identification of extrachromosomal genetic determinants. Twenty-six isolates from different geographic origin, 14 deriving from France, 3 from ex-Yugoslavia, 3 from Argentina, 1 from Romania, 5 from Italy, have been studied. Extrachromosomal bands have been detected in most isolates. Rnase A and DNA exo-nucleases (exo-III and exo-λ) digestions suggested they were DNA plasmid-like elements apparently with a circular conformation. More detailed analysis was then performed on a selected plasmid derived from a French isolate presumably present, as inferred by molecular weight, in all French and Yugoslavian isolates (countries were the disease has a heavy incidence). Its intracellular localisation resulted to be mitochondrial. In order to check its specificity, it was used in Southern blot experiments as a probe against DNAs derived from all twenty-six D.helianthi isolates. Further investigations are needed to characterise that plasmid (cloning and sequence analysis) and to make a comparison (e.g. RFLP) with plasmids from the other D.helianthi isolates.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11384/1353
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