Plant Biology

McKnight and NIH awards fertilize plant growth research

New faculty member Bill Gray, assistant professor of plant biology, has attracted substantial support for his research.

Morning glories twine around fence posts. Spruce trees spire to the sky. Apple buds burst into flower, then form fat fruits. We human inhabitants of this green planet are as familiar with plant growth as we are with the sun above our heads and the soil beneath our feet. Many of us are also familiar with the hormone— auxin —that prods plants to grow. But even scientists who have spent their lives studying auxin can’t tell you how it does its job.

Bill Gray intends to do something about that. An assistant professor in the Department of Plant Biology, Gray recently landed a five-year, $1.04 million National Institutes of Health grant to explore how this multi-talented molecule tells plant cells when, where, and how to grow.

Gray started studying auxin in the mid-1990s. He found that, though people know plenty about how it affects various plants under various circumstances, nobody knows much about the mechanisms by which it does its job.

“There are literally libraries full of volumes describing what auxin can do,” Gray says. “Now we need to learn how it actually works.”

To do so, Gray has been tapping the talents of Arabidopsis thaliana,a member of the mustard family whose speedy life cycle and relatively simple genetics have made it the botanical equivalent of the laboratory mouse. Several years ago Gray and colleagues used a sequence of experiments—involving isolating mutants in which auxin doesn’t work right, identifying the faulty gene, and studying the protein that gene makes—to discover what appears to be a key step in the cascade of occurrences that translate the presence of auxin into actual plant growth.

In a 2001 article in the journal Nature, the researchers described the molecular interplay: Auxin causes a complex called SCFTIR1 to connect with proteins that repress the plant’s ability to respond to auxin. SCFTIR1 attaches a protein called ubiquitin to the repressors, marking them for degradation. With the repressors out of the way, auxin is then able to modulate plant growth and development.

Supported by the NIH grant, Gray is now working to identify other links in the chain of events initiated by auxin. “We have a good handle on this one step,” he says. “Now we want to try to work backwards up the pathway to determine how the hormone eventually impinges on this step.”

The information Gray is gaining may be useful not only in understanding— and potentially manipulating— plant growth, but also in understanding human systems controlled by similar regulatory mechanisms. Recognizing the potential, in January the University awarded Gray a McKnight University Professorship, which gives junior faculty recognition for exceptional work and additional resources for enhancing their research programs.

Honored and energized by the NIH grant and the McKnight professorship, Gray figures he has his work cut out for him. Even if he gets the auxin pathway down pat, he expects the knowledge gained will open doors to whole new universes of questions and answers about growth and development.

”It’s likely to keep me busy for a long time,” he says.

—Mary K. Hoff