How plants grow in a spurt during the night

Washington, September 16 : Scientists have discovered the genes that control the phenomenon of plants growing in a spurt during the night.

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.

These genes, which 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 Oregon State University (OSU).

Ultimately, more understanding of these growth genetics could allow scientists to create plants that grow faster, produce more food or have other useful characteristics, according to the researchers.

"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," he added.

According to Mockler, when such mechanisms are more fully analyzed, it may be possible to influence them with genetic modification.

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.

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.

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.

According to scientists, identifying that regulator could open the door to ways to control plant growth and yield.

ANI