Poster: Evolution

Abs # 791: Mechanism of dihaploid induction in Solanum spp. and the evolutionary consequences of the phenomenon.

Presenter:	Boutaoui, Nadia , abr99nb@rdg.ac.uk
Authors	Boutaoui, Nadia  (A)   Wilkinson, Michael  (A)
Affiliations:	(A): School of Plant Sciences, University of Reading, UK

Interspecific hybridization is of major importance in plant evolution, and is a key force driving the genetic improvement of cultivated crops. When hybridization occurs, the proportion of the DNA contributed by the paternal parent can vary enormously. In certain interploidy crosses more than half of the genome may derive from the father whereas in some apomictic crosses, there is no paternal contribution. Some interspecific crosses between Solanum spp. of different ploidy level generate offspring that are almost entirely maternal but include a small genetic contribution from the male parent. The offspring usually possess half the chromosome number of the tetraploid maternal parent and so are called dihaploids. The amount of DNA transferred from the male parent is variable but typically around 2%. Cytological and genetic evidence is presented to suggest that degraded paternal DNA integrates directly into the host genome upon sperm release into the embryo sac by a process termed pseudofertilization. Here, we describe a hypothesis to explain the mechanism of transfer and explore possible evolutionary consequences of the phenomenon.