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Imagine thousands of cells undergoing a very carefully, planned suicide - to
survive - that is what plants do on a daily basis. However, in some cases it
proves to be detrimental. Researchers in Ardmore have now found a way to
improve plant survival by preventing plant cells from undergoing programmed
cell death (PCD), April 2005 by Flora Mauch, Checkbiotech.

PCD is a normal component of the development and health of multi-cellular
organisms. Thus, it has not necessary something to do with a disease. Cells
die in response to a variety of stimuli, and during PCD they do so in a
controlled, regulated fashion.

But why should a cell commit suicide?

One reason is the need for a proper development. For example, the formation
of the water pipes in plants requires the help from PCD. This long-distance
transport system, called the xylem, consists of several cell layers that
depend on PCD in order to develop properly.

PCD may also result from abiotic or biotic stress. For example, when a virus
infects a plant, the plant may sacrifice several of its cells to PCD, in
order to prevent the spread of the virus infection.

In previous experiments, several research groups have expressed animal PCD
regulating genes in plants and found the function of their encoded proteins
conserved in plants. These studies suggest the conservation of PCD
regulation across the kingdoms. As mentioned before, PCD is a highly
regulated process. This entails the existence of many factors acting for, or
against, PCD.

Taking this to account, the research team from the Samuel Roberts Noble
Foundation in Ardmore, headed by Dr. Marilyn J. Roossinck, developed
transgenic tomato plants expressing animal anti-PCD genes. As a result they
obtained genetically modified tomato plants showing changes in growth and
seed development. Upon infection with a certain virus, the enhanced
transgenic plants showed delayed cell-death symptoms through PCD, or even
the absence of symptoms.

In addition, the engineered plants were more resistant to low temperatures.
All in all, the expression of animal anti-PCD genes improved plant survival
under different environmental stresses.

The results reported in this study indicate a potential agricultural value
for these transgenic plants. However, Dr. Roossinck rather sees these plants
as a good system for further studies with plant PCD.

?We do basic research. That means we are trying to understand the underlying
processes that takes place in plants to cause the phenotypes we see. If
there is any application to our work, it will be done by others.?

[www.pnas.org]

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