Ask A Scientist© Biology Archive

name         Dixenia
status       student
age          15

Question -   What can you tell me about the Ti Plasmid?
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This plasmid is named for a plasmid found in a bacteria called Agrobacter
tumefaciens.
It causes "plant cancer" or what are known as galls.  They are little tumors
in which the bacteria can grow and live in the plant.  Ti stands for tumor
inducing.  The bacterium gets into the plant through some kind of wound, ie.
a scratch.  It injects its plasmid into a plant cell and the plasmid inserts
its DNA into the plant's DNA.  Then the DNA directs the plant to make a
hollow tumor where the bacteria can live.  Scientists have taken advantage of
this plant's ability to insert foreign DNA into a plant.  They take the genes
out of the plasmid that cause galls, and insert genes of interest, ie. genes
for pest resistance and let the plasmid carry those genes into the plant.
The plant will start making the product you want.  You may have seen a
picture of a tobacco plant glowing because firefly genes for glowing were
inserted into the plant.  They did this so they could know if the gene had
made it into the plant.  Once they are sure the gene they want has made it
into the plant, they clone the plant cells.  By the way, plant tissue culture
is a procedure that is very common and has been done for years, this is not
the same as cloning animals.

Van Hoeck
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