COLLEGE STATION Mirror, mirror on the wall, how do legumes provide for us all?
Scientists are hoping that a $3.5 million National Science Foundation grant will answer that. A thorough genomic study of a simple legume species may be the looking glass for more complex crops such as soybeans.
The legume family is one of the most important groups of plants worldwide, according to Dr. Doug Cook, Texas Agricultural Experiment Station plant pathologist and lead scientist on the project. Legumes - - including soybeans, alfalfa and peas -- are important sources of protein in human and livestock diets. They also are valuable oil crops and provide a vital source of nitrogen, a kind of natural fertilizer, to the biosphere.
Soybeans, perhaps the most well known of the legumes, are expected to yield some 2.9 billion bushels valued at about $13.5 billion this year for the nation's farmers, according to the U.S. Department of Agriculture.
The project will analyze the total DNA or genome of Medicago truncatula, a simple legume which can serve as a model for the other, more complex legumes, Cook said. Medicago is a forage crop, called barrel medic, that is grown in Australia and Africa, and closely related to alfalfa.
The Medicago research project is another leaf on a vine of the NSF's massive plant genome project which parallels the human genome initiative. Much plant genome work stems from research on Arabidopsis, a weed that is virtually unknown to the general public but widely regarded in the scientific community. Arabidopsis is the standard for plant genomics because it has only the essential DNA, so to speak.
More complex plants, anything from soybeans to pine trees, have the same or similar genetic makeup but also lots of so-called "junk" DNA packed in the chromosomes as well. That makes it hard for scientists to know where to begin looking for desirable traits in the complex plants. But by finding a desired genetic marker in Arabidopsis, researchers get a hint of where it might be found in the more complex species.
Cook and his colleagues hope that Medicago will be for legumes what Arabidopsis is for plants in general -- a simple plant that can model where desirable genes reside in the DNA of more complex legumes such as soybeans, alfalfa and peas.
"If we know the basics of DNA structure and function that occur in Medicago, then we can extrapolate to the crop legumes," Cook said. "Our challenge is to move from the simple model plants to the more complex and economically important crop species."
With nine other scientists and a host of graduate and postdoctoral students, Cook will compare the Medicago genome with other legumes and with Arabidopsis, study the functions of the expressed genes, and develop a database program to disseminate the genomic information on Medicago.
The project will span at least three years, but Cook said information drawn from the work will be mined by public and private researchers for decades to come. He said Medicago can be thought of as the "looking glass" for scientists now and in the future to look at the data that is generated through this project and see how it compares to other legumes or plants in general.
"Perhaps we won't find exactly the same genes in soybean that we find in Medicago," he explained, "but we might be led to their counterparts.
"For example, we may examine the genetic basis of agriculturally important processes such as nitrogen and phosphorous metabolism or oil production in the seed," Cook said. "Identification of the genes that underlie these processes in Medicago should direct us to the related genes in other plant species."
Crop breeders whose goal is to continually develop improved crops will be able to extract valuable information from the research, Cook said, as the scientists learn about processes that are economically important to agriculture and consumers. He expects the project to begin yielding weekly information, which will be posted on the Web, within a year.