At 6:57 PM -0500 10/18/99, David Hershey wrote:
>Whole plants can synthesize thiamin yet thiamin is apparently essential
>in plant tissue culture media. Does anyone know why thiamin is essential
>for tissue culture?
>>David Hershey
>dh321 at excite.com
Hi David!
A small group of vitamins are synthesized by leaf
and or root tissues for use by plants. It is my
understanding that when you do NOT have mature
tissues that these essential vitamins are required
for growth, proliferation, and regeneration of
plants from explants or meristemoids. Thus they
would be essential for certain kinds of tissue
cultures.
That said, it is also quite clear that if you are
culturing ORGANIZED tissues to whole plants, then,
the requirement might be eased or eliminated. It is
common practice to move regenerating tissues from
complex media to simpler media to simple mineral-only
media as plants develop in vitro.
In my own work with tobacco cultures (after genetic
transformations of explants) I take this exact
approach. As I get to more complete plants, the need
for axenic culture is eased, the need for open containers
is obvious for better gas exchange, and the vitamins,
carbon sources, and so on of earlier subcultures have
to GO if I want to keep the plants free from overgrowth
of contaminants. The organized plant tissues can make
the required vitamins for the final stages of development
before the leap into soil. The last subculture before
soil is a medium that contains mineral salts and the
solidifying agent (for tobacco in our conditions, nothing
beats Phytagel) this is the ONLY organic in the medium.
ross
________________________________________________________________
Ross Koning | koning at ecsu.ctstateu.edu
Biology Department | http://koning.ecsu.ctstateu.edu/
Eastern CT State University | phone: 860-465-5327
Willimantic, CT 06226 USA | fax: 860-465-4479
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