"Callus" vs "meristem" tissue
Al
I searched the two books I have on the subject and I must have missed it.
It seems to me I should be able to find a definition of one or the other
word that tells me for sure if they are synonyms and if not, how are they
different. I think they are synonyms, no?
Thanks, Al
R. Halgren
represents a growing point. You knew that. Callus is a proliferation of
meristem tissue lacking secondary structure. Consider it a tumor. In this
case, a benign tumor. However, as with all proliferative growth, with
increased DNA replication comes an increased chance of mutation. Hence the
various oddities that can come out of meristem props.
Rob
Al wrote:
--
___
Robert G. Halgren, PhD.
hal...@pilot.msu.edu
(517)432-6337
Al
questions to think about and I am going to make my own answer after reading
yours and doing more sniffing around.
Making a Dolly of my own won't be possible yet but now I have a much better
understanding of the process by which new plants are made from plant tissue.
I think part of my confusion comes from the fact that the two terms are
often used to mean the same thing when speaking in general of the *stuff* in
the culture dish that becomes the new plant. In this sense they are
synonyms
In a more specific sense one is part of the other; i.e. callus tissue
contains meristematic tissue or, maybe more accurately, it contains
meristematic cells. Callus, I think, is the semi-differentiated tissue that
forms around and can be made from wounded plant cells of many different
types (leaf, roots etc.). Root tip and shoot tip cells are those used most
often to make the callus tissue because these cells are the least
specialized. Callus can be made to multiply indefinitely or to
differentiate into a complete plant depending on what chemical and/or
environmental stimulants are applied. Not all callus grows into new plants.
Some of it sclerifies and eventually dies.
Here is an interesting webpage that offers a history from the first culture
of root cali to the culture of a complete Cymbidium ensifolium:
http://www.rrz.uni-hamburg.de/biologie/b_online/e29/29a.htm
Al
Leanne Forsyth wrote in message ...
>A callus is a mass of undifferentiated cells which divide without creating
>form (like leaves/roots/flowers etc) unless stimulated to (by
>hormones/light etc). A meristem is a region of plant cells which are
>undifferentialted dividing to give cells which differentiate (into other
>cell types like leaf tissue/stem tissue etc)
Leanne Forsyth
TQPL
You might also like to consider the historical complications unique to the
orchid work. The original work on cloning orchids back in the 1960 was
called mericloning hence mericlones a term that has persisted to designate
cloned plant, usually orchids from the meristematic dome. Later is was
discovered that all you need is an active growing tip, which contained a
meristematic dome or actively growing tissue. Then strictly it become tissue
culture. Other general usage terms such as micropropagation were adopted by
some to differentiate from pure meristem culture. Now the general term of
plant tissue culuture can be used to encompase a whole range or techniques.
There is also the unique term stem propagation or stem props which is a form
of tissue culutre or micropropagation or plant tissue culture propagation
that is applied to Phalaenopsis.
Sorry if that is all complicated, it used to be simple in the old days when
it was only orchids but the non-orchid propagators were the ones to
complicate it!
Best regards
Alan L Winthrop.
TQP...@awinthrop.freeserve.co.uk
Al
tripped me up a couple of times. This is the first time I have heard
"meristematic dome." I think I understand what group of cells that "dome"
refers to the stem, root or other growing tip. I used to think that there
was a *single* cell in the tip called a meristem that needed to be isolated
and removed from all other more differentiated cells as the first step in
the process of cloning. I hadn't realized how much the plant's natural
processes help out. I couldn't for the life of me figure out how anybody
without a very good microscope, tiny, tiny tools and a very steady hand
could do that magic trick. -Al
TQPL wrote in message <8d2stk$tpl$1...@news6.svr.pol.co.uk>...
Aaron Hicks
The great thing is that you don't need to slice open all your
tender growing shoots to acquire meristem material and produce some callus
tissue. Start with something cheap and simple- like carrots. You can now
buy "Clone in a Box" kits from folks like Carol Stiff, or from much larger
companies like Carolina Biological. I know CB has kits where you can buy
carrot, miniature roses (small enough to flower in a 1" tube, I think),
venus' flytrap, sundews, and many others.
Carol is at:
http://www.home.turbonet.com/kitchenculture/
Carolina Biological is at:
http://www.carolina.com/
-AJ
TQPL
You are right the principle meristematic regions are in the stem tip, root
tip and axillary buds or dormant buds. The meristematic dome is surrounded
by leaf primoria which develop later into leaves. It is possible to isolate
the meristematic dome by removing a square area when looking through a good
hand lens. You can break down razor blades to make mini scalpels fixed into
split bamboo with epoxy adhesive. Nowadays it is most common to use a good
mini scalpel blade and a binocular microscope works wonders, especially if
looking at something big like a cymbidium shoot.
The smaller the dome the more difficult the whole process becomes.
Hope this gives you some insight.
Regards
Alan
TQP...@awinthrop.freeserve.co.uk
"Al" <A...@OrchidExchange.com> wrote in message
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