'Biological clock'
genes control plant growth
Source:
September 16, 2008
CheckBiotech
CORVALLIS, Ore. - More than 125 years ago Charles Darwin
first reported that most plants grow in a spurt during the night, not the day -
and this week, scientists are reporting the discovery of the genes that control
this phenomenon.
These rhythmic growth
spurts, and the ability of plants to move in response to light, are actually
controlled by genes involved in circadian rhythms – the "biological
clock" genes that are influenced by light and dark, vary their activity
based on time of day, and are increasingly found in both plants and animals to
control a wide variety of functions, ranging from growth to nervous system
function and even fertility.
"This is an incremental but important step in
understanding how plants grow," said Todd Mockler,
an assistant professor of botany at
Ultimately, more understanding of these growth genetics
could allow scientists to create plants that grow faster, produce more food or
have other useful characteristics, the researchers said.
The findings will be reported this week in PloS Biology, a professional journal. The research was
funded by the National Science Foundation, National Institutes of Health and
the Howard Hughes Medical Institute.
"We now know that the expression of certain genes and
hormones at night and just before dawn is important for plant growth," Mockler said. "During the day, the plant focuses on
other tasks, such as the photosynthesis that produces its energy. And plants
are not only responding to time of day, but also the length of daylight to
control such things as flowering time and stem length."
When such mechanisms are more fully analyzed, it may be
possible to influence them with genetic modification, Mockler
said.
This advance was made possible largely by the use of DNA
microarrays and bioinformatics, most of which was done at OSU. This technology
allows powerful computers to be combined with more conventional biological
research to examine thousands of genes in an organism, in a very short period
of time, and determine which ones are active and what their role is.
Researchers now believe that almost all plant genes are
expressed only at a particular time of day, depending on the growth condition.
And they use growth and movement to maximize their chance of survival in a
competitive environment – a plant leaf, for instance, will literally move if it
becomes shaded by another plant.
In 1880, in one of his lesser-known works that was not
focused on animal evolution,
The findings in this study were made with the plant
Arabidopsis, a small plant in the mustard family that is often used as a model
for genetic research. A glowing enzyme, luciferase,
was attached to the genes that were identified as responsible for rhythmic
growth. And it would glow, on and off, as the genes began functioning to create
the hormones responsible for growth in the dark of night.
The research program also learned that most of the genes
involved in this process have a common DNA sequence, which they called the
"HUD" element for "hormone up at dawn."
Further studies are needed to identify a protein that
attaches to this HUD element and regulates its function. Identifying that
regulator, the scientists said, could open the door to ways to control plant
growth and yield.
CONTACT:
Todd Mockler
tmockler@cgrb.oregonstate.edu
541-737-0787
Source:
greenbio.checkbiotech.org