Journal of Molecular Evolution (2007) 64, 489-499

Nicolas Feau, Richard C. Hamelin and Louis Bernier (2007)
Variability of nuclear SSU-rDNA group introns within Septoria species: Incongruence with host sequence phylogenies
Journal of Molecular Evolution 64 (5), 489-499
Abstract: We report structural features and distribution patterns of 26 different group I introns located at three distinct nucleotide positions in nuclear small subunit ribosomal DNA (SSU-rDNA) of 10 Septoria and 4 other anamorphic species related to the teleomorphic genus Mycosphaerella. Secondary structure and sequence characteristics assigned the introns to the common IC1 and IE groups. Intron distribution patterns and phylogenetic relationships strongly suggested that some horizontal transfer events have occurred among the closely related fungal species sampled. To test this hypothesis, we used a comparative approach of intron- and rDNA-based phylogenies through MP- and ML-based topology tests. Our results showed two statistically well-supported major incongruences between the intron and the equivalent internal transcribed spacer (ITS) tree comparisons made. Such absence of a co-evolutive history between group I introns and host sequences is discussed relatively to the intron structures, the mechanisms of intron movement, and the biology of the Mycosphaerella pathogenic fungi.
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Link to article at publishers website
Database assignments for author(s): Richard C. Hamelin, Louis Bernier

Research topic(s) for pests/diseases/weeds:
molecular biology - genes
identification/taxonomy

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Pseudocercospora fijiensis	Banana/plantain (Musa)
	Sphaerulina musiva	Poplar/aspen (Populus)
	Sphaerulina betulae	Birch (Betula)
	Pseudocercospora eustomatis	Banana/plantain (Musa)