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Copyright 2004 by the Genetics Society of America Mating Within the Meiotic Tetrad and the Maintenance of Genomic
 

Summary: Copyright 2004 by the Genetics Society of America
Mating Within the Meiotic Tetrad and the Maintenance of Genomic
Heterozygosity
Michael E. Hood1
and Janis Antonovics
Department of Biology, University of Virginia, Charlottesville, Virginia 22903
Manuscript received June 9, 2003
Accepted for publication January 16, 2004
ABSTRACT
Mating among the products of a single meiosis (automixis or meiotic parthenogenesis) is found in
diverse groups of plant, animal, and fungal taxa. Restoration of the diploid stage is often strictly controlled
and brings together products separated at the first meiotic division. Despite apparent similarities to diploid
selfing, the theoretical prediction is that heterozygosity should be maintained on all chromosomes when
it is linked to the centromeres and thus also segregates at the first meiotic division. Using the fungus
Microbotryum, we directly test this prediction by linear tetrad analysis. The patterns of meiotic segregation
for chromosome size variation (electrophoretic karyotypes) and PCR products (AFLP procedures) were
determined for Microbotryum lineages native to North America and Europe. Our data reveal a surprisingly
dynamic genome that is rich in heterozygosity and where size-dimorphic autosomes are common. The
genetic variation agrees with the prediction of centromere-linked heterozygosity. This was observed to the
greatest extent in the lineage of Microbotryum native to North America where there was consistent first-

  

Source: Antonovics, Janis - Department of Biology, University of Virginia

 

Collections: Biology and Medicine