Photo: Les Todd

t six foot three, Philip Benfey towers incongruously over the bedraggled-looking collection of shriveled plants that he displays with considerable pride. The plants languish in plastic pots on a shelf in his laboratory's closet-like plant-growth room. They remain stubbornly, even ungratefully stunted, although they bask in brilliant artificial sunlight, ensconce their roots in the best soil, and imbibe the scientifically determined optimal measure of water and fertilizer.

However, to Benfey, who is chair and professor of biology at Duke, the puny plants constitute the intellectual equivalent of giant redwoods. These particular mustard plants, scientific name Arabidopsis thaliana, harbor a fascinating gene mutation that eliminates a key growth-regulating gene. The mutation interferes with subtle biochemical signals between cells in their growing roots--stunting them, and, thus, the entire plant. In contrast, the normal plants nearby reach for the sun--or rather the brilliant artificial light in the growth room. They stretch their gangly stems upward about a foot, supported by clear plastic cylinders. Benfey studies what happens when arabidopsis genes known as "Short Root" and "Scarecrow" are mutated, in effect, broken so that they don't work properly. His work has yielded extraordinary insights into how these growing roots develop.

While Arabidopsis might seem an obscure bit of foliage, the little plant is celebrated among geneticists as the laboratory mouse of the plant kingdom. A relative of cabbage and radishes, Arabidopsis is small and prolific and grows easily and quickly.

	Driven by Data
	A Scientist's Indirect Path

Benfey's studies of the plant's tiny tangled roots might be considered just a minor botanical curiosity if they applied to only one species. But his research is helping science get to the ... well ... root of one of the central questions in all of biology: the immensely complex puzzle of how entire tissues, whether plant roots or human brains, blossom from a single cell. The solution would advance a vast range of disciplines from agriculture to medicine. And the Arabidopsis root has afforded Benfey and his colleagues a ringside seat at the biological spectacle of the development of living tissue.

"The root has a fairly complex structure, with lots of different cell types. And it all begins from a single cell," says Benfey. But unlike the impossibly intricate convolutions and migrations of developing animal bodies, each new Arabidopsis root cell arises conveniently from its neighbor. "When you look at the anatomy of the root, the origins of the entire structure are right there in front of you," he says. "You can see all the stages of development. For genomics, this is an enormously simplifying feature."

Thus, says Benfey, exploring the consequences of mutations in just a single gene such as Short Root or Scarecrow can yield a world of insight into tissue development. Biologists, including Benfey and his cohorts, are gleeful scientific saboteurs, mutating genes to make them malfunction and keenly observing the resulting biological havoc. (The scientists, perhaps perversely, often name genes according to the ill effects of breaking them. The origin of the name Short Root is rather obvious; the mutation of the Scarecrow gene produces roots missing a critical layer of root cells--like the missing brain in the Wizard of Oz character.)

Sabotaging genes is especially informative because they are the blueprints for the multitude of proteins that make up the machinery that keeps cells--from plant roots to hair roots--functioning. A sabotaged blueprint produces a nonfunctional protein, disrupting that machinery in interesting and instructive ways. Benfey's research has revealed that Scarecrow and Short Root are blueprints for proteins that help form the same growth machinery pathway in the plant root.