Genes Controlling Rhythmic Plant Growth Identified

While most people might assume that plants grow at a slow and steady rate throughout the day, scientists have known that they grow in regular nightly spurts, with plant stems elongating fastest in the hours just before dawn. Charles Darwin was so enthralled with his observation of rhythmic plant movements that he wrote a book on the subject (The Power of Movement in Plants). Recently, scientists from UC San Diego, the Salk Institute for Biological Studies and Oregon State University have identified the genes that control the interplay of plant hormones and circadian rhythms that permit plants to undergo rhythmic growth spurts in response to environmental cues. The discovery of the genetic basis of rhythmic plant movements, which fascinated Darwin more than a century ago, may allow scientists to design crops that can grow faster and produce more food.

The scientists say that the genes, which mostly deal with hormone biosynthesis and signaling, act together to regulate rhythmic plant growth like a gate with its hinges controlled by photoreceptors and the biological clock—opening in the predawn hours to allow a wave of growth hormones to act within the cells, then closing the gate to put the brakes on plant growth until the next 24-hour cycle.

The researchers discovered that the genes share a common DNA sequence, a master controller that they dubbed the HUD (Hormone Up at Dawn) element. The scientists are now on a quest to identify the regulator protein that binds to the HUD element, as they believe that it is very important for controlling plant growth and yield.

For more information, read http://ucsdnews.ucsd.edu/newsrel/science/09-08PlantGenes.asp Download the paper published by PLoS Biology at http://dx.doi.org/10.1371/journal.pbio.0060225