Oyama, R. K. , Volz, S. M. , Renner, Susanne S. .
Divergence of the X and Y homologs of a sex-linked SCAR marker in the Cucurbitaceae Bryonia dioica, a species with XY sex determination.
Genetic crosses between the dioecious Cucurbitaceae Bryonia dioica and the monoecious B. alba in 1903 provided the first clear evidence for Mendelian inheritance of dioecy and made B. dioica the classic case of XY sex determination in plants. Applying molecular tools to this system, we developed a male-linked SCAR marker for B. dioica and sequenced it for individuals representing almost the full distribution range of the species from Scotland to North Africa. For comparison, we included representatives of the dioecious species B. cretica, B. multiflora, and B. syriaca, and monoecious B. alba as an outgroup. In no case did any individual, male or female, yield more than two haplotypes, and no female had a Y sequence. All Y sequences recovered from males in Northern Europe were identical to each other, and a phylogeny of all sequences shows a clade of these northern males and another of the X-homologs. However, three males from a Southern European population yielded two X sequences and no Y sequence. Population genetic analyses suggest that the sequenced region experienced different evolutionary pressures in Northern and Southern Europe, and that some Southern populations have not yet lost diversity on the Y chromosome due to occasional recombination. These findings fit with phylogenetic evidence that the XY system in Bryonia is labile and match findings in Silene latifolia, which, different from Bryonia, has heteromorphic sex chromosomes.
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1 - University of Munich, Organismal Biology, Menzingerstr. 67, Munich, 80638, Germany
Presentation Type: Poster:Posters for Topics
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM