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  • From: Heron Breen <breen@fedcoseeds.com>
  • To: North American Fruit Explorers <nafex@lists.ibiblio.org>
  • Subject: [NAFEX] Question about Sports and Causes
  • Date: Thu, 17 Feb 2005 22:34:44 -0600

Hey Doc,
I am wondering: Background Radiation and environmental mutation, can they be
based
on a mitochondrial "immune" response, stimulating altered or heightened DNA
replication? Or is it primarily free radical damage to the DNA, mitochodria,
or
other structures? Is the former "immune" response usually stable? I guess
what I am
wondering about is changes not during cell division, ie possibly gene
expression?
If I am totally off base, what would be the celluar explanation for mutation
caused
by grafting onto rootstocks? Your very informative posts make me wonder about
some
talk a few months back about persimmons changing characteristics when
grafted, to
the point where one would be unable to identify the cultivar. I wonder
whether
said "mutation" would revert to true to type form if scion wood was taken
from
the "mutated" persimmon and grafted back onto the mother tree? Is there any
possibility that the mother tree could be altered by such an action? Just
trying to
understand more, I apologize if I am not quite grasping this concept.

My thoughts are that many times a bud sport is only noticed after grafting.
There
are some theories that it is the grafting itself which causes the "sporting".
Can
you answer whether this could be an environmental cause of the "physical
inefficiencies" that cause "sports"? How and/or why?

In my scientific bumbling trying to ask a question,
Heron Breen


On Thu Feb 17 15:15 , 'Stephen Sadler' <Docshiva@Docshiva.org> sent:

>A sport is another example of a type of mosaicism, although the genetically
>different cells are not distributed throughout the plant. A sport occurs
>when there is suppression of some genetic material through 'random
>mutation', which can be caused by normal background radiation or exposure to
>other environmental factors. It can also be due to crossover, especially in
>a rapidly reproducing set of cells (such as a bud). As the cells divide, a
>gene at the end of one chromosome can become attached to a different
>chromosome due to simple physical inefficiencies in the process of cell
>division. One of the newly divided cells may end up with no copies of a
>gene, and another with an extra copy. The resulting sport would be a
>mosaic.
>
>Stephen Sadler, Ph.D.
>USDA 9, AHS heat zone 8,
>Sacramento CA - Mediterranean climate
>
>




  • [NAFEX] Question about Sports and Causes, Heron Breen, 02/17/2005

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