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

christian foster <flatnflashy@yahoo.com> wrote:

So then, if I'm extrapolating correctly, Assuming (of course) that the reason flats don't make pollen is because the pollen genes are blocked by methyl. It's possible then that if you could get a flat/flat cross and crossed the resulting seedlings then potentially the methyls could be stripped off the pollen making genes and the F2 seedlings could produce pollen? 

christian
ky
   
  I doubt that the reason most flats don't make pollen is the methyization of DNA.   The methyization of pollen and sperm DNA is the norm in plants and animals.  It would be as likely to happen in normal iris as in flat ones.
  And it is generally small amounts of DNA that are turned off this way.  Most genes work no matter which parent they come from.  But some don't and seem to skip a generation if inherited from the father.
  If this was a common situation, Mendal would never have figured out genetics.
  I first became aware of this methylization reading about two genetic defect syndromes in humans.  It had, after decades of study, been determined that two syndromes were due to the same dominant gene.  The milder syndrome was when it was inherited from the father, the more severe syndrome was when it was inherited from the mother.  And it was not on the sex chromosomes, nor were hormones involved in the difference.
  Since then, other genes have been found to be turned off (or turned down) when passed through pollen or sperm, turned back on when passed through the egg.
  This system seems to be very ancient, going back to the progeneter of both plants and animals.  Yet it seems to not act on many genes.  An exception is the X chromosome in mamals, where the female has 2 and males only one and a Y.  Many genes, not all of them nor even most of them, are methylated one one of the X chromosomes.  This appears to reduce the gene differences between males and females.  But even there many genes are functioning fine on both X chromosomes.
  Another case of reciprical crosses giving different results is in interspecific peanut crosses.  A X B does not equal B X A.  Yet grow out a population from each of those crosses and the difference between the populations is reduced in each generation.  After 4 to 6 generations, the differences are gone.  So the differences seem not to be cytoplasmic, nor methylization, nor any known cause.
  There is still a lot to learn about genetics.
  All I was origionally trying to say was that differences between reciprical crooses may not be due to cytoplasmic inheritance.  The practical difference is that the cytoplasmic inheritance keeps being carried through only the seed parent, or mother in animals.  the methylization only causes the trait to skip the generation where the gene comes from the pollen or sperm.
  I wonder if the SA iris breeders have noticed anything like this.  I'll have to ask on that group.
  Walter
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