Hybrid Sterility and Inviability in the Parasitic Fungal Species Complex Microbotryum

J Evol Biol. 2009 Apr;22(4):683-98. doi: 10.1111/j.1420-9101.2009.01702.x. Epub 2009 Feb 18.

Abstract

Microbotryum violaceum, the anther-smut fungus, forms a complex of sibling species which specialize on different plants. Previous studies have shown the presence of partial ecological isolation and F1 inviability, but did not detect assortative mating apart from a high selfing rate. We investigated other post-mating barriers and show that F1 hybrid sterility, the inability of gametes to mate, increased gradually with the increasing genetic distance between the parents. F2 hybrids showed a reduced ability to infect the plants that was also correlated with the genetic distance. The host on which the F2 hybrids were passaged caused a selection for alleles derived from the pathogen species originally isolated from that host, but this effect was not detectable for the most closely related species. The post-mating barriers thus remain weak among the closest species pairs, suggesting that premating barriers are sufficient to initiate divergence in this system.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Basidiomycota / genetics
  • Basidiomycota / physiology*
  • Chimera / physiology*
  • Chromosome Segregation / genetics
  • Genome, Fungal / genetics
  • Genotype
  • Germ Cells / physiology
  • Receptors, Pheromone / genetics

Substances

  • Receptors, Pheromone