FORT COLLINS--A.S.N. Reddy's experiment on the space shuttle Columbia should help explain how plants tell up from down.

Colorado State University's Reddy wants to look at what happens at the molecular level that tells a plant's root to grow down and a shoot to grow upward. It's an important question: Thirty years after humans first walked on the moon, the emphasis has shifted to the space station and longer manned space flights, possibly to other planets.

The problem is that plants -- an important source of food and oxygen and a means of recycling carbon dioxide -- aren't ready for the weightless condition known as microgravity.

"A root always grows down, a process known as gravitropism, which means root cells have some mechanism to know where gravity is," said Reddy, an associate professor of biology. "The relevant cells are in a one-millimeter area at the root tip called a root cap. But at this point we don't know which genes are involved in sensing gravity's signal."

After three days of growth aboard the Columbia, 240,000 tiny seedlings of Arabidopsis, a common weed closely related to mustard, will be frozen in liquid nitrogen, stopping all biological action and preserving molecular information. Reddy says about 13,000 genes--some 65 percent of the plant's total--have been sequenced (that is, the order of each gene's nucleotides is known). The investigators will use that and other information to determine which genes are activated or deactivated by gravity.

Reddy, in collaboration with Donald Mykles, professor of biology, and the late Willy Sadeh, former director of Colorado State's Center for Engineering in Spaces Sciences, has received $280,000 for his work from NASA. Some of the experiments will be performed with Monsanto Chemical Co., which has equipment with the capability to examine thousands of genes at a time. Then the real work begins--an analysis of genetic changes that Reddy e
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Contact: David Weymiller
dweymiller@vines.colostate.edu
970-491-6851
Colorado State University
23-Jul-1999