Re: Marcotrigiano not good enough?
>Marcotrigino shows mit rec it suddenly is not important He
>shows a twinspot ie 2 adjacent spots, a green and a white one If
>you would have know anything about the subject you had
>recognized that such a twinspot is a classical proof for mit rec.
Twin spots can also arise from chromosome loss. Given the high doses
or iriadation that are needed to develop conditions that suggest
mitotic recombination, it it just as likely, maybe more so that what
you see is the result of irriadiation induced chromosome damage. If
you want to prove it is mitotic recombination and not chromosome loss
then you have to do genetic analysis of the resulting twin spots.
Difficult to do when it is only a very tiny spot on a leaf surface.
Now, Ben, no one is claiming that mitotic recombination does not take
place in higher plants. All we are saying is that the rate of mitotic
recombination is so LOW that it is not a factor in explaining green
edges showing up on yellow hostas. If you think mitotic recombination
is the cause for this, then prove it. If you look at all the
experiments where twin spots were developed that indicate that mitotic
recombination occure you will see that these are SMALL spots on a leaf
surface - a far cry away from resulting in a variegated plant. I
don't know how many millions of cells a tobacco plant has, certainly
in the tens if not hundreds of millions. After growing out hundreds
of plants that were heavily irriadated they could only come up with
one small spot to indicate mitotic recopbination, and still couldn't
prove it. The problem you are failing to understand Ben is that if a
mitotic recombination were to take place that resulted in a L1-L2
layer green-yellow chimera, it would have to occure in the apical
meristem cells to form a periclinial chimera or in one of the daughter
cells of the apical meristem cells to form a mericlinal chimera that
could then be convered to a periclinal chimera. You are not only
taking about an event occuring that has a VERY low chance of occuring,
without irriadiation maybe in the order of 1 in ten billion cell
divisions, AND that mitotic recombination has to take place in the
shoot apex. You are just asking for too much.
Now, irriadiation is well known to cause chomosome damage. It seems
very lofgical to me that when you treat a plant with high doses of
radiation that any spots that develop that appear to be the expression
of a gene where you wouldn't expect that expression is the result of
chromosome damage due to irriadiation. If you think I am wrong, then
PROVE that mitotic recombination is the cause. We have two equally
plausible explinations for a given event. We both can't be right,
although we can both be wrong. Until such time as you can PROVE
otherwise I say I am correct!
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