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Repeat-Induced Point Mutations Drive Divergence between Fusarium circinatum and Its Close Relatives

Stephanie van Wyk1, Brenda D Wingfield1, Lieschen De Vos1

  • 1Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Private Bag X20, Pretoria 0028, South Africa.

Pathogens (Basel, Switzerland)
|December 19, 2019
PubMed

Insights

Repeat-Induced Point (RIP) mutation is a fungal defense mechanism. In Fusarium fungi, RIP significantly impacts genomes, driving divergence and altering chromosome structure.

Area of Science:

  • Fungal genomics
  • Molecular evolution
  • Population genetics

Background:

  • Repeat-Induced Point (RIP) is a fungal-specific defense mechanism against transposable elements.
  • RIP introduces permanent cytosine to thymine (C-to-T) mutations in targeted DNA sequences.

Purpose of the Study:

  • To investigate the genome-wide occurrence and impact of RIP in *Fusarium circinatum* and related species within the *Fusarium fujikuroi* species complex (FFSC).
  • To understand how RIP influences genome evolution, chromosome structure, and species divergence in this important fungal group.

Main Methods:

  • Genome-wide analysis of RIP mutations across multiple FFSC species.
  • Comparative genomics to assess the extent and distribution of RIP across core and dispensable chromosomes.
  • Analysis of gene density and sequence variability in RIP-affected regions.

Main Results:

  • All examined FFSC fungi showed evidence of RIP, with varying degrees of genomic impact.
  • RIP mutations were prevalent across both core and dispensable chromosomes, with higher prevalence on dispensable chromosomes.
  • Large RIP-affected regions were gene-poor and contributed to sequence diversification between homologous regions of related species.
  • RIP interfered with homologous recombination, leading to post-mating segregation distortion.

Conclusions:

  • RIP is a major driver of genomic diversification and chromosome evolution in the FFSC.
  • RIP contributes to the divergence of chromosomes and the overall evolutionary trajectory of *Fusarium* species.
  • The findings highlight RIP's role in shaping the genome architecture and reproductive isolation within this fungal complex.
Keywords:
Fusarium circinatumRIPRepeat-Induced Point mutationsgenome evolutionlineage divergencesegregation distortion

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