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Researchers from Michigan State University have identified two cooperating
genes whose products mediate leaf growth, December 2004 vy Flora Mauch,
Checkbiotech .

Temperatures drop, the last leaves fall off the trees, and soon snow will
cover the country I live in, Switzerland. Winter is approaching, and people
already enjoy the special mood before the holiday season. But what would
winter be like without being without the prospects of spring that will
follow?

When the lifelessness of winter is followed with a burst of growth, we often
are left to wonder how nature orchestrates this change. Researchers who
looked into the question of how leaf growth is regulated and what genetic
and biochemical factors determine leaf growth, are Drs. Jeong Hoe Kim and
Hans Kende from the DOE Plant Research Laboratory at Michigan State
University.

In previous studies, Dr. Kende?s group identified the role of the
Arabidopsis thaliana growth-regulating factor (AtGRF) gene family, whose
members encode factors that play a regulatory role in the growth and
development of leaves. These factors are proteins that bind to DNA and
function to initiate, enhance, or inhibit gene expression. In their latest
studies, Drs. Kim and Kende discovered a family of three genes called
GFR-interacting factors (GIFs) as well as their role in leaf growth. As the
name implies, GIF cooperates with GRF in influencing gene expression,
thereby affecting the growth and shape of leaves. Such a protein is called a
coactivator in the world of molecular genetics.

To prove their findings, Dr. Kende and his laboratory showed that transgenic
Arabidopsis plants expressing high levels of GIF resulted in a similar
phenotype as transgenic Arabidopsis plants expressing high levels of GFR.
Either transgenic plants produced larger leaves when compared to control
plants.

In the course of their experiments, Drs. Kim and Kende also noticed that the
GIF transgenic plants were sterile. With the inability to pass on the added
genes, transgenic plants expressing higher levels of GIF would not be able
to pollinate neighboring crops. This would be beneficial to growers who are
concerned about genetically modified plants crossing with other plants.

Another fact supporting the notion that GIF acts as a coactivator is its
sequence similarity to human SYT, which is a well-known coactivator.

Now that more is known about the development of plant leaves, the question
arises of how this knowledge could be used in agriculture. One example can
be found in medicinal plants. Often medicinal chemicals are found in the
leaves of plants. In such cases, a genetically engineered plant producing
higher levels of GIF, would have larger leaves, thereby increasing the
amount of medicinal compounds that growers could harvest. The increased
yields could reduce costs to the grower as well to the consumer in form of
more affordable medicinal drugs.

Dr Kende?s work is a considerable step in plant biology and should lay the
foundation for promising agricultural improvements in the future.

Flora Mauch is a Science Writer for Checkbiotech in Basel, Switzerland and
is currently studying Biology.
[www.checkbiotech.org]

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