Mitochondrial introgression and interspecies recombination in the Fusarium fujikuroi species complex

Gerda Fourie,Brenda D Wingfield,Nicolaas A Van Der Merwe,Michael J Wingfield,Emma T Steenkamp,Mesfin Bogale

doi:10.5598/imafungus.2018.09.01.04

Gerda Fourie, Brenda D Wingfield + Show 4 more

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https://doi.org/10.5598/imafungus.2018.09.01.04

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Journal: IMA Fungus	Publication Date: Feb 27, 2018
Citations: 19	License type: open-access

Affiliation: University of Pretoria

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.

Highlights

IntroductionThe Fusarium fujikuroi species complex (FFSC, previously referred to as the Gibberella fujikuroi species complex) is one of several monophyletic assemblages in the genus Fusarium (phylum Ascomycota, order Hypocreales) (Geiser et al 2013)
The Fusarium fujikuroi species complex (FFSC, previously referred to as the Gibberella fujikuroi species complex) is one of several monophyletic assemblages in the genus Fusarium (Geiser et al 2013)
Previous work suggests that the FFSC likely emerged during the middle-to-late Miocene (O’Donnell et al 2013) and that its evolutionary history could KDYH LQYROYHG LQWHUVSHFLHV JHQH ÀRZ 2¶'RQQHOO &LJHOQLN 1997)

Summary

Introduction

The Fusarium fujikuroi species complex (FFSC, previously referred to as the Gibberella fujikuroi species complex) is one of several monophyletic assemblages in the genus Fusarium (phylum Ascomycota, order Hypocreales) (Geiser et al 2013) This complex is well-known for the many welldocumented plant pathogens and mycotoxin producers it includes (Kvas et al 2009). Previous work suggests that the FFSC likely emerged during the middle-to-late Miocene (O’Donnell et al 2013) and that its evolutionary history could KDYH LQYROYHG LQWHUVSHFLHV JHQH ÀRZ 2¶'RQQHOO &LJHOQLN 1997) Such interspecies interactions have been described from other Fusarium species (e.g. F_oxysporum and F. graminearum species complexes) (Ma et al 2010, O’Donnell et al 2000a) and, in the FFSC, was suggested to explain the existence of multiple non-orthologous copies of the internal transcribed spacer region of the ribosomal RNA genes (O’Donnell & Cigelnik 1997). In many Fusarium species, including those in the FFSC, laboratory-based mating studies have shown that the level of reproductive isolation is not complete and that various species are capable of interbreeding (Desjardins et al 2000, Leslie et al 2004b)

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