Yves.Dessaux at isv.cnrs-gif.fr
Tue May 20 11:56:20 EST 1997
In article <5l866g$gtl at sjx-ixn4.ix.netcom.com>, epiphany at ix.netcom.co
>I have a few questions about the bacteria above:
>What type of plants does the A. tumerfaciens infect by plasmid
>transfer? What does the plasmid transfer do to the plant? What genes
>are expressed by the plasmid?
Essentially dicots. Some gymnosperms. Some Monocots, but in this
later case, symptoms are generally not visible... Genes expressed
in plants are located on the T-DNA (transferred DNA):
- Aux genes reponsible for auxin synthesis
- Cyt genes responsible for cytokinin synthesis. Expression
of these two set of genes provoke the deregulation of the
control of the plant cell cycle and pro!ote the unregulated growth
of the plant cell, hence the formation of the tumor.
- ops genes reponsible for the synthsis of opines which are
low molecular weight compounds specific for crown gall tumors.
These are used by the bacteria as growth substrates and some
promote the transfer of the Ti plasmid between bacteria
>I understand that A. tumerfaciens can increase ethylene production in
>carrots. Are there any other plants/fruits/vegetables in which the
>bacteria can do this? Is this quality in any way related to the
>plasmid transfer above? I'm not sure if there is a connection, but a
>book I was reading led me to believe that there was one, although there
>was no attempt to make a connction between the two phenomena. Can
>anyone tell me more about this phenomena (ethylene increase) as well?
I have never read any convincing data on the increased production
of C2H2 by plants infected by Agrobacterium... besides, there are no
functions encoded on the T-DNA that could trigger overproduction
of C2H2 ...
>In addition to posting at the news group, please send me a response at
>epiphany at ix.netcom.com. Thanks! Ana
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