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Characterisation of a length polymorphism in the two intergenic spacers of ribosomal RNA in Puccinia striiformis f. sp. tritici, the causal agent of wheat yellow rust

Published online by Cambridge University Press:  24 October 2002

Céline ROOSE-AMSALEG
Affiliation:
Unité de Pathologie Végétale et Epidémiologie, INRA, BP01, F-78850 Thiverval-Grignon, France. Unité de Phytopathologie et Méthodologie de la Détection, INRA, Route de Saint-Cyr, F-78026 Versailles, France.
Claude de VALLAVIEILLE-POPE
Affiliation:
Unité de Pathologie Végétale et Epidémiologie, INRA, BP01, F-78850 Thiverval-Grignon, France.
Yves BRYGOO
Affiliation:
Unité de Phytopathologie et Méthodologie de la Détection, INRA, Route de Saint-Cyr, F-78026 Versailles, France.
Caroline LEVIS
Affiliation:
Unité de Phytopathologie et Méthodologie de la Détection, INRA, Route de Saint-Cyr, F-78026 Versailles, France.
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Abstract

Sequences of the intergenic spacer between the 28S and the 5S rDNA genes (IGS 1) were compared for three European isolates belonging to three Puccinia striiformis f. sp. tritici races, of different geographic origins and virulence spectra. Two PCR products (IGS 1-1 and IGS 1-2, of 1.3 and 1.1 kb, respectively) were recovered from all spore multiplications. The analysis of IGS 1-1 or IGS 1-2 showed that a low mutational polymorphism existed between the three isolates (from 0.7 to 1.1%) and that each IGS 1 type was characterised by a succession of repetitions. The comparison of IGS 1-1 and IGS 1-2 to each other showed that the polymorphism between the two types of IGS was due to a length polymorphism consisting of a 216 bp insertion/deletion located in the repeated region. Two hypotheses can be proposed to explain the coexistence of two different IGS 1 types within one isolate: either each nucleus of this dikaryotic fungus contains one type of IGS 1 or there are two discrete ribosomal units resulting from recombination in the same nucleus.

Type
Research Article
Copyright
© The British Mycological Society 2002

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