From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Sat Dec 07 2002 - 14:32:21 MST
On Sat, 7 Dec 2002, Barbara Lamar wrote:
> With respect to cloning multicellular plants, I should add that my success
> rate with roses is 50% to 75%. Higher with plants such as Ligustrum
> japonicum Mentha species. Lower with certain trees such as Sophora
> secundiflora. Lower still with annuals -- that is, plants that germinate,
> produce flowers and seeds, and die within one growing season.
Interesting. One would suspect that annuals would have less DNA
repair capacity -- they invest all of their energy into their
seed production and less into maintaining the "soma" of the plant.
(This is Kirkwood's "disposable soma" theory of aging.)
One would expect that plants bred to survive many years (e.g. roses)
would have better DNA repair and better clonability. But at success
rates of 50-75% it shows that even with many cells one may not have
a sufficient number of "perfect" genomic copies to replicate the plant.
There really is a study that needs to be done here on "cloning" plants
from single cells. I know the methods are developed for separating
mammalian cells into single cells and culturing them but I don't
know enough about plant structure to know whether or not single
cells can be used or a collection of cells of different types
is a minimal requirement.
It might be an interesting experiment Barbara, for you to see
if your success rate falls as you decrease the size of the
cutting. That would seem to suggest that cloning "success"
is a numbers game. (Mind you with the size of cuttings you
can actually "see", you are still dealing with millions to
billions of cells).
Robert
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