HYB: disease resistance
Walter Pickett mentions in his post on Iris-photos the difference in the
seedlings in the first couple of generations in reciprocal crosses in
It is important to remember that not all DNA is in the nucleus, and in the
There are a series of structures in the cytoplasm (those parts, collectively,
that are not inside the nuclear membrane). Among these are the mitochondria,
made famous in human studies tracing human dispersal out of East Africa
beginning by at least 60,000 years ago. All (or perhaps most) of all human
populations alive today are descended from that out-migration. How do the
experts know this? Because in the DNA found in the <mitochondria>, which are
derived ONLY from the mother, a steady rate of mutation occurs.
Using those accumulating mutations, unique for each branch of the human
population as it dispersed, it is possible to draw a family tree with the
migrations showing for all humans on earth.
Another famous use of mitochondrial DNA came up in the question of whether
"Anastasia" was in fact a survivor from Czar Nicholas' family when the
Communists executed the entire family. Both the genuine Anastasia and I
believe Philip, husband of Elizabeth II in England, share a maternal ancestor
in common--Queen Victoria. Did they match? No. So Anastasia was not the
Why does this kind of thing work? Simply because <everything> outside the
nucleus comes from the mother in the reproductive process. Animal spermatazoa
and plant pollen contents come from the nucleus alone. The paternal parent
contributes nothing to the cytoplasm of the offspring.
So there are certain functions and processes that are inherited from the
mother alone. Do these make a difference in the offspring--occasionally yes,
but usually in no significant ways. There are significant exceptions,
Genetic traits originate from within the nucleus, which is a combination of
the contributions of both parents.
The structures outside the nucleus are "housekeeping" functions--such as the
chemical factories that follow the codes on the DNA and manufacture various
proteins according to the DNA blueprint instructions. There are others that
have to do with pigments and energy exchanges--the plastids or chloroplasts.
What happens inside those with the pigments, however, again are according to
blueprints from nuclear DNA.
One place where maternal DNA in the cytoplasmic structures has been observed
is in the first generation hybrids between arils and Eupogons (pure
"true-bearded"--which is what Eupogon means-- European diploids and the
tetraploids of the AMAS sort). Hybrids using the Eupogons as maternal
parents, I believe it was observed by C. G. White, tended to show a
predominance of bearded ancestry traits. Those with aril maternal ancestry
were the reverse. All of the famous diploid hybrids such as William Mohr, or
C. G. White's OYEZ and others of similar origin have the oncocyclus parent as
the pod parent.
There may be some aspects of growth, such as disease resistance, vigor or
other matters that are maternal in origin in our modern hybrids.
Neil Mogensen z 7 western NC mountains
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