While roots obviously carry food and water to the leaves, the new findings help show how roots also send chemical signals that control whether or not leaves grow. How leaves grow is a crucial matter given that leafy plants supply food for humans and other creatures, produce oxygen for all animals to breathe, influence global climate and grace us with the current season of brilliant fall colors.

"When we look at plants, it's easy to think only about the above-ground parts you can see," says Leslie Sieburth, who led the study and is an associate professor of biology at the University of Utah. "But this study shows that the roots potentially play a huge role in addition to supplying water and nutrients in controlling how the plant comes to look as it does. It's very easy to ignore the root, but our study shows we shouldn't."

Manipulating the process someday might allow scientists to genetically engineer crops and other plants to be more productive in dry conditions for example, so that crops could keep producing abundant leaves in a drought by irrigating them while overriding the genetic signal that normally would inhibit growth, Sieburth says.

The new study was published in the Oct. 5 issue of the journal Current Biology by Sieburth, graduate student Jaimie Van Norman and Rebecca Frederick, who formerly worked in Sieburth's laboratory and now is a graduate student in biochemistry.

Seeking the Secrets of How Leaves Grow

Sieburth's research focuses on a seemingly simple question: "How do leaves grow? It's a basic biological question," she says.

Plants look different depending where they grow. A dandelion, for example, may be very leafy in Florida's humid climate, but have only small leaves
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4-Oct-2004