IMA Fungus 9(1): 27-36, doi: 10.5598/imafungus.2018.09.01.03

Multiple independent origins for a subtelomeric locus associated with growth rate in Fusarium circinatum

Emma Steenkamp, Brenda D. Wingfield^‡, Lieschen De Vos^§, Quentin C. Santana^|, Nicolaas A. Van Der Merwe^|, Emma T. Steenkamp^¶

‡ University of Pretoria, Department of Genetics and Forestry and Agricultural Biotechnology Institute (FABI), Pretoria, South Africa§ University of Pretoria, Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), Hatfield, South Africa| University of Pretoria, Department of Genetics, Forestry and Agricultural Biotechnology Institute (FABI), Pretoria, South Africa¶ University of Pretoria, Department of Microbiology and Plant Pathology, Forestry and Agricultural Biotechnology Institute, Pretoria, South Africa

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Citation: Steenkamp E, Wingfield BD, De Vos L, Santana QC, Van Der Merwe NA, Steenkamp ET (2018) Multiple independent origins for a subtelomeric locus associated with growth rate in Fusarium circinatum. IMA Fungus 9(1): 27-36. https://doi.org/10.5598/imafungus.2018.09.01.03

Abstract

Fusarium is a diverse assemblage that includes a large number of species of considerable medical and agricultural importance. Not surprisingly, whole genome sequences for many Fusarium species have been published or are in the process of being determined, the availability of which is invaluable for deciphering the genetic basis of key phenotypic traits. Here we investigated the distribution, genic composition, and evolutionary history of a locus potentially determining growth rate in the pitch canker pathogen F. circinatum. We found that the genomic region underlying this locus is highly conserved amongst F. circinatum and its close relatives, except for the presence of a 12 000 base pair insertion in all of the examined isolates of F. circinatum. This insertion encodes for five genes and our phylogenetic analyses revealed that each was most likely acquired through horizontal gene transfer from polyphyletic origins. Our data further showed that this region is located in a region low in G+C content and enriched for repetitive sequences and transposable elements, which is situated near the telomere of Chromosome 3 of F. circinatum. As have been shown for other fungi, these findings thus suggest that the emergence of the unique 12 000 bp region in F. circinatum is linked to the dynamic evolutionary processes associated with subtelomeres that, in turn, have been implicated in the ecological adaptation of fungal pathogens.

Keywords

Fusarium temperatum, horizontal gene transfer, Pitch canker fungus, transposable elements