Colloquia: Systematic and Evolutionary Perspectives on Apomixis
Speranza, Pablo .
The spread of apomixis in Paspalum dilatatum: from apomict to apomict.
The Dilatata group in the genus Paspalum (Poaceae) is a polyploid agamic complex of warm season grasses native to temperate South America. Due to the efforts to domesticate the common pentaploid form (P. dilatatum ssp. dilatatum), extensive collections, cytogenetic information and evolutionary hypotheses have accumulated over several decades making the group a very promising model to analyze evolutionary processes in apomictic complexes. The group comprises a few sexual tetraploid forms which are mostly reciprocally allopatric and several apomictic tetraploid to heptaploid biotypes. Most apomictic biotypes were shown to be monoclonal; however, the common pentaploid form includes more variability than previously thought. Although one dominant clone has been found globally in all the populations analyzed, hybridization occurs where the pentaploid biotype is sympatric with some of the sexual tetraploids and novel local pentaploid clones are formed. Even-ploid apomicts, although cytologically capable of facultative apomixis, seem to have played a minor role in the evolution of the complex. Although other Paspalum species consist of sexual diploids and conspecific apomictic autotetraploids, P. dilatatum can be viewed as a tetraploid/pentaploid system in which the pentaploids carry an unpaired genome coding for apomixis. The genetic analysis of apomicts at all ploidy levels in shows that they can be putatively derived from one another suggesting a single origin for the apomixis genome which has been subsequently transmitted without recombination from apomict to apomict
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1 - Facultad de Agronomía, Universidad de la República, Plant Biology, Av. E. Garzón 780, Montevideo, 12900, Uruguay
Presentation Type: Symposium or Colloquium Presentation
Location: 551A/Convention Center
Date: Wednesday, August 4th, 2010
Time: 2:15 PM