Citation
Mirete, Salvador and Patiño, Belén and Jurado García-Posada, Miguel and Vázquez, Covadonga and González Jaén, María Teresa
(2013).
Structure Variation And Dynamics of the Nuclear Ribosomal Intergenic Spacer Region in Key Gibberella Fujikuroi Complex Species.
"GENOME", v. 56
;
pp. 205-213.
ISSN 0831-2796.
Abstract
The intergenic spacer (IGS) region of the ribosomal DNA was cloned and sequenced in eight species within the
Gibberella fujikuroi
species complex with anamorphs in the genus
Fusarium
, a group that includes the most relevant toxigenic
species. DNA sequence analyses revealed two categories of repeated elements: long repeats and short repeats of 125 and 8 bp,
respectively. Long repeats were present in two copies and were conserved in all the species analyzed, whereas different numbers
of short repeat elements were observed, leading to species-specific IGS sequences with different length. In
Fusarium subglutinans
and
Fusarium nygamai
, these differences seemed to be the result of duplication and deletion events. Here, we propose a model
based on unequal crossing over that can explain these processes. The partial IGS sequence of 22
Fusarium proliferatum
isolates was
also obtained to study variation at the intraspecific level. The results revealed no differences in terms of number or pattern of
repeated elements and detected frequent gene conversion events. These results suggest that the homogenization observed at the
intraspecific level might not be achieved primarily by unequal crossing-over events but rather by processes associated with
recombination such as gene conversion events.