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Cynthia Weinig

Cynthia Weinig was recently named a McKnight Land-Grant Professor.

Way to grow

Searching for genes that make plants stand out in a crowd

By Mary K. Hoff

June 2, 2006

If you or I don't like something in our surroundings--bright sun, loud music, the smell of sauerkraut--we can usually move to a more desirable setting. Plants, however, don't have this ability, Instead, they modify their growth to accommodate local conditions.

This knack for making the most of their circumstances is the subject of study for Cynthia Weinig, assistant professor in the Department of Plant Biology.

"My focus is on understanding genes that allow plants to adapt to their natural settings," Weinig says.

When she joined the College of Biological Sciences in 2002, Weinig brought with her a five-year, $1.7 million National Science Foundation Young Investigator award to study how plants' genes help them cope with crowding. She's been looking at the interaction of two genetically controlled variables, circadian rhythm and shade-avoiding growth, in Arabidopsis thaliana and Brassica rapa as they struggle to outcompete their neighbors for access to sunlight.

"By minimizing shade avoidance, we may well increase crop productivity," Weinig says.

Scientists have long known that a drop in the ratio of red to far-red light activates genes that enable "shade-avoidance" responses such as stem elongation. (Chlorophyll absorbs red light, so a low red-to-far-red ratio suggests the presence of nearby neighbors.) However, most studies of the genetics for shade avoidance have been in controlled settings using plants in which key genes have been deleted. Those studies are of limited value, Weinig says, because the genes may not be those on which natural selection acts today or that account for phenotypic variation. In fact, Weinig has found that variation in only a few of the genes affecting shade avoidance appear to affect current fitness. These genes, interestingly, appear to interact with those controlling circadian rhythms.

Weinig's research not only is improving understanding of the interplay of genes, environment, and structure, it also has practical application. Farmers try to increase yield by increasing plant density. If plants respond with increased stem growth, the production of commercially valuable leaves, roots, and fruits may suffer. "By minimizing shade avoidance, we may well increase crop productivity," Weinig observes.

In related research, Weinig is studying how flowers react to environmental cues. Although floral morphology is thought to be buffered against environmental variation, Weinig has found that expression of floral traits depends in part on the red-to-far-red ratio, photoperiod, and temperature. Because floral morphology affects pollinator effectiveness, such variability could alter the production of fruits and seeds that feed us.

In January the Graduate School and the Office of the Provost named Weinig a McKnight Land-Grant Professor in recognition of her exceptional contributions. The award provides research support for two years as well as a research leave during the second year of the professorship.

"I'm honored," Weinig says. "I appreciate the validation of the work I've done since I've arrived at Minnesota."

Republished from BIO spring 2006, a publication by the College of Biological Sciences.