Mystery of the four-leaf clover unraveled by scientists at the Noble Foundation, University of Georgia at Athens

NEWS RELEASE
Issued - July 6, 2010

ARDMORE, Okla. — Turns out, the lucky four-leaf clover – a universal symbol of good fortune – is not the result of an ancient mystical force, just a special group of genes.

Research conducted by scientists at The Samuel Roberts Noble Foundation and the University of Georgia at Athens (UGA) has discovered genes responsible for causing this natural phenomenon, helping answer century-old questions about inheritance of multiple leaves in white clover.

While multiple genes dictate leaf color and shape, the study discovered a "repressor" gene specifically responsible for limiting the production of clover leaves. When the gene does not function, which can occur naturally, white clover plants develop four or more leaves.

"The four-leaf clover is a natural variation seen in nature for centuries," said Joe Bouton, Ph.D., director of the Noble Foundation's Forage Improvement Division and plant breeder. "There has been speculation about the role of inherited genes and the number of genes that cause this variation, but it has been virtually impossible to track. Until now."

The scientific team, which included UGA researchers Rebecca Tashiro and Wayne Parrott, and Noble Foundation scientists Yuanhong Han, Maria Monteros and Bouton, used traditional breeding as well as advanced technologies like molecular markers to find the gene. Molecular markers serve as road signs on a plant's genome, identifying specific genes and allowing scientists to trace them through several generations of testing. "This makes the breeding process highly efficient and keeps the scientist from guessing if the genes of interest are present in a plant," said Monteros, Ph.D., assistant professor and plant breeder. "We can check for the marker and know that the plant contains a specific, associated gene."

"This is a great time to be involved in white clover breeding" said Parrott, Ph.D., the senior researcher of the study at UGA. "Comprehensive genetic resources for breeding once were limited to commodity crops. Now we are developing such tools for other crops, for example, white clover, which is an important grazing forage domestically and internationally."

The U.S. Department of Agriculture characterizes white clover as "the most important pasture legume." Widely adapted to geographies around the world, white clover serves as a highly palatable, nutritious forage for all classes of livestock.

The Noble Foundation-UGA team conducted the experiment over the course of several years, growing white clover populations in Oklahoma and Georgia. The populations were grown in both outdoor and indoor environments during the winter and the summer. The findings indicated that environmental conditions played a significant role in clovers developing multiple leaves.

The same study that unearthed the four-leaf clover gene also found genes responsible for the "red fleck" and "red midrib" color variations that appear in clover leaves. Scientists can now use these genes to produce white clover plants having leaves with varied color patterns. This discovery will initially allow for the development of new ornamental types of white clover, but this research serves as a platform for more significant benefit.

Clover leaves can naturally produce a red pigmentation, or anthocyanins. Anthocyanins are believed to have certain health-benefiting characteristics. Leaves producing specific types or greater amounts of anthocyanin are capable of delivering such beneficial compounds to consuming humans and ruminant animals, such as cattle.

Additionally, experience gained through this experiment can be applied to other legumes which play an important role in agriculture. Legumes take nitrogen from the atmosphere and – using special bacteria in their roots – turn it into its own source of fertilizer, which can defer input costs for agricultural producers.

"Genes that help make four-leaf clovers and control the color pigmentation are interesting traits to study," Monteros said. "The results are easy to recognize. However, we're applying the same technology to discover more complex traits, such as drought tolerance. Technologies such as molecular markers allow us to develop a better variety faster so they can get into the hands of farmers and agricultural producers."

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For media inquiries concerning the Noble Foundation, please contact:

J. Adam Calaway

jacalaway@noble.org

The Samuel Roberts Noble Foundation, Inc. (www.noble.org), headquartered in Ardmore, Okla., is a nonprofit organization conducting agricultural, forage improvement and plant biology research; assisting farmers and ranchers through educational and consultative agricultural programs; and providing grants to nonprofit charitable, educational and health organizations.