Re: Re: HYB: If you could ignore hybridizing barriers...(q

Robt R Pries <rpries@sbcglobal.net> wrote:
  .............. Note, as
you probably know, the same cross but reversing the
plant that is pod parent will give different results.
I like to think of the pod parent as the main
contributor to growth habits (physiology and
metabolosm) because of the cytoplasmic inheritance.
  //////// Another reason for reversing the cross giving different results is the process of methylation of DNA.  Some DNA  in the pollen (and in sperm of animals) will have methyl moleculews azttached during pollen formation.  This shuts off those genes for that generation.  Then when the pollen and eggs are made for the next generation, the methyl molecules are stripped off, and the process is repeated.
  When the DNA is replicated before regular cell divission, the same DNA that has the attached methyls will be replicated with attached methyls.
  SBy this method, some genes from the father's side sit out the generation.  Or they are just turned down in some cases, still showing some effect.
  This was discovered just a few years back.
   
  
Also don't give up on plants that seem infertile the
first year. Fertility usually increases with time.
Also poor growers can develop into better growers as
time goes by. I suspect both of these instances are
due to cells weeding out chromosome artifacts that
interfere with cell division and that may have
occurred with an initial wide cross. 
  /////// I suspect that it is a case of a bigger stronger plant giving more flowers to pollinate.  But I'm not sure.  Breeders working with many genera report the improved fertility of older plants.
  Walter
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