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4088Ploidy in plants... and people too!

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  • matthew chappell
    Dec 1, 2005
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      Hello all,

      There are only two conclusive ways to determine IF any species is
      tetraploid. Well... one for sure (karyotyping) and another (GC- Mass Spec)
      will confirm it and tell you the size of the genome as well. The first
      method is simple... staining the chromosomes and making a karyotype. This
      has been done with some azaleas. For reference see:

      Li, Hui-lin. 1957. Chromosome Studies in the Azaleas of Eastern North
      America. American Journal of Botany 44:8-14.

      Sax, Karl. 1930. Chromosome Stability in the Genus Rhododendron. American
      Journal of Botany. 17: 247-251.

      The second method... GC-mass spec literally counts the number of base pairs
      of each chromosome as it passes through an extremely small pore. It will not
      accurately determine if the plant is tetraploid because you must first have
      an image of the chromosomes to see if there are identical chromosomes
      present (hence tetraploid). Together, both methods would give a very
      accurate measurement of ploidy and genome size.

      Hope this helps. Just keep in mind that guessing on ploidy is a tricky
      business. Wheat is a great example. Wheat is a synthetic hexaploid yet is
      neither more vigerous than its ancestors nor self/cross incompatable despite
      having sets of chromosomes from a vast array of the Triticum genus.

      Peace be with you all.

      Matthew R. Chappell
      Georgia Agricultural Experiment Station
      Horticulture Dept.- Plant Breeding & Genetics
      1109 Experiment Street
      Griffin, GA 30223
      Office- (770) 229-3369
      Cell- (770) 715-6585

      -----Original Message-----
      From: azaleas@yahoogroups.com [mailto:azaleas@yahoogroups.com] On Behalf Of
      Sent: Thursday, December 01, 2005 3:16 PM
      To: azaleas@yahoogroups.com
      Subject: Re: [AZ] Doing crosses with Rhododendron occidentale?

      I just repotted a few seedlings of a cross of Rh. atlanticum and Rh.
      luteum that a friend in California made. I think both are probably

      Mike Creel, Zone 8A, SC

      This study reported R. atlanticum as diploid and a single triploid.
      There must be tetraploids elsewhere.

      Larry Wallace

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