Jasieniuk:Notebook/Apomixis in hybrid Rubus/2010/07/19

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Experimental Design

List of mother plants

  • Two genotypes of R. ursinus x armeniacus: are these apomictic or sexual?
  • One genotype of R. ursinus x pensilvanicus: is this apomictic or sexual?
  • R. ursinus: expect to see sexual recombination (dioecious)
  • R. armeniacus: expect ~90% asexual progeny
  • R. pensilvanicus: expect to see mostly asexual progeny
  • R. ulmifolius: an extra control; should reproduce sexually
  • Another clone that is similar to R. armeniacus: also expect to see ~90% asexual progeny. This clone is included because it was unexpected that we found a second invasive clone on the West Coast, and so characterizing it in general would be a good idea.

Microsatellite markers

These are chosen based on how much heterozygosity they show in our mother plants of interest.

  • CBA15 - only really useful in the R. armeniacus types
  • CBA23
  • CBA28 - should be especially useful
  • CBA14
  • RUB126 - also should be very useful
  • RUB262

Analysis

The simplest thing to do is, for each group of mother plus progeny, calculate a pairwise distance matrix between individuals. Then we will look at the distributions of within-group distances. Shorter distances indicate apomixis, while larger distances indicate sexual reproduction. Mother plants that have a mix of the two reproductive modes should show a bimodal distribution.

A more complex analysis could involve looking at the probabilities of seeing certain genotypes under the hypotheses of sexual and asexual reproduction. Theoretically we should expect 100% identical genotypes under asexual reproduction, but we should leave some wiggle room for mutations or scoring errors.

Some References

  • Ellstrand & Scierenbeck: Hybridization as a stimulation for the evolution of invasiveness in plants? [1]
  • Kollmann et al.: Evidence of sexuality in European Rubus species based on AFLP and allozyme analysis. [2]
  • Amsellem et al.: Evidence for a switch in reproductive biology of Rubus alceifolius towards apomixis, between its native range and area of introduction [3]
  • Werlemark & Nybom: Pollen donor impact on the progenies of pseudogamous blackberries. [4]

PCR Run today

Stella, you can put whatever notes you like in here about what you are doing.


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