Abstract:
The Fusarium fujikuroi species complex (FFSC) is an economically
important monophyletic lineage in the genus Fusarium. Incongruence observed
among mitochondrial gene trees, as well as the multiple non-orthologous copies
of the internal transcribed spacer region of the ribosomal RNA genes, suggests
that the origin and history of this complex likely involved interspecies gene
flow. Based on this hypothesis, the mitochondrial genomes of non-conspecific
species should harbour signatures of introgression or introgressive hybridization.
The aim of this study was therefore to search for recombination between the
mitochondrial genomes of different species in the FFSC. Using methods based on
mt genome sequence similarity, five significant recombinant regions in both gene
and intergenic regions were detected. Using coalescent-based methods and
the sequences for individual mt genes, various ancestral recombination events
between different lineages of the FFSC were also detected. These findings
suggest that interspecies gene flow and introgression are likely to have played
key roles in the evolution of the FFSC at both ancient and more recent time scales.
