TIGR to Help Decipher Genome of Model Legume
Sequencing of Medicago truncatula Will Benefit Nutrition, Agricultural Research
October 28, 2003
Rockville, MD - The genome of an alfalfa relative that is used as a research model for legumes - an important group of plants that includes soybeans, lentils, and chickpeas - will be deciphered in a collaborative project that includes The Institute for Genomic Research (TIGR).
That model legume, Medicago truncatula, will become the third plant species to be fully sequenced. TIGR also played key roles in deciphering the first two plant genomes: the model plant Arabidopsis thaliana and rice, Oryza sativa.
Deciphering the Medicago genome is expected to yield many benefits to agriculture and nutrition research because the plant is used by scientists as a model for studying legumes, which are distinguished by their ability to acquire high protein content by producing their own fertilizer by means of nitrogen fixation. Legumes also produce compounds, such as phytoestrogens and isoflavones, that benefit human health.
The National Science Foundation (NSF) has funded the Medicago project with $10.8 million as part of its plant genomics program. The University of Oklahoma and TIGR will conduct the sequencing itself, while the University of Minnesota will oversee the project and the integration of the data with other Medicago resources. The U.S. group is part of an international consortium that includes research centers in France and the United Kingdom which will sequence two of Medicago's eight chromosomes.
"Thanks to the mapping efforts of other Medicago researchers in the United States and in Europe, we have been able to focus our efforts on the gene-rich portions of the genome, making the process of gene discovery faster and more cost-effective," says Christopher Town, TIGR's lead investigator on the Medicago project.
Over the last three years, Town's group at TIGR has sequenced more than 80,000 coding portions of genes (known as Expressed Sequence Tags, or ESTs) from the Medicago genome. Town also leads TIGR's Arabidopsis genome annotation project. Other TIGR groups are annotating the rice genome and exploring the maize genome.
A research group led by Bruce Roe at the University of Oklahoma's Advanced Center for Genome Technology will conduct most of the Medicago sequencing for the U.S. portion of the project. Roe's group, with support from The Nobel Foundation, has been sequencing parts of the model legume's genome, including its chloroplast.
The Medicago genome, with an estimated 500 million base pairs of DNA, is about four times the size of the Arabidopsis genome. Nevin Young, a plant biologist at the University of Minnesota's College of Agricultural, Food, and Environmental Sciences, will lead the Medicago project. Noting that legumes "are responsible for a majority of the biologically generated nitrogen in the world," Young says the Medicago genome sequence will be invaluable to future plant research.
"With the genome sequence, scientists can sit down and look at all the pieces involved in making health-promoting compounds, converting nitrogen to a usable form, and packing legumes with protein," says Young.
Town says the Medicago project will help in the study of the basic biology of other legumes: "Just as the rice genome serves as a model for the wide range of cereal crops, Medicago will play a similar role in helping us understand the many legumes - such as soybean and peas - that are important to human nutrition."