"Rodger Whitlock" wrote in
message ...
On Sat, 23 Aug 2003 09:40:09 +0100, Charlie Pridham wrote:

As regards identical genes, true but its not the only thing that affects
what a plant looks like, in the case of Hostas the colouring of leaves
in
certain ways is not wholly genetic but partly viral therefore plants
will
not come true. It
is well known that microproping can clear up virus from plants, but in
some cases (ie Camelia) the virus is what causes the difference in
flower
colour. Many named scented leaf pelargoniums will not come true by
microprop
(I don't know why). But the following quote from one of my manuals may
give
a clue "When insufficient precautions are taken the appearence of
"Sports"
genetic mutants or off types may be increased" apparently when callus
material forms it is very gentically unstable.

There is also the fact that the expression of genes is by no
means as simple as one might think. Classical Mendelian genetics
is a starting point, but real life turns out to be far more, and
extraordinarily, complex. It was Barbara McClintock, I believe,
who won a Nobel prize for her work on genetics, starting with the
simple everyday observation that certain strains of corn have
many different colors of kernels in a given ear. And then she
wondered "how does that happen?"

I am lost again. My (limited) understanding is that the expression of genes
is determined by other genes. Now, in the case of clones, the genes whose
expression interests us and the "other" genes are all identical to those of
the parent. Their expressions should therefore also be identical. So far
the only case which I can see for a cloned "offspring" being different from
its "parent" would seem to be the presence or absence of a virus, or some
similar intruder, as Charlie mentioned.

Franz