Medicago truncatula

Understanding genetic diversity in the model legume Medicago truncatula

Legumes, the third largest family of flowering plants, are notable for their ability to form symbiotic relationships that lead to tremendous amounts of biological nitrogen worldwide, providing a major source of organic fertilizer and vegetable protein for humans and animals. Medicago truncatula is a widely studied model species for legume genomics and one important question focuses on the identity of naturally occurring genes that control variation in symbiosis in legumes. In collaboration with Dr. Nevin Young and colleagues at the University of Minnesota and Dr. Maria Harrison at the Boyce Thompson Institute, Drs. Mudge and May will use association mapping techniques to create a Medicago "HapMap". In brief, 384 diverse genetic lines obtained from collaborators at INRA-Montpellier, Ecole National Superieur Agronomique de Toulouse (ENSAT) and the Noble Foundation will be resequenced using next generation sequencing technology at NCGR to identify sequence polymorphisms (SNPs) between the different Medicago lines. The massive database of SNPs between Medicago lines enables the prediction of genome segments with shared ancestry (haplotypes), which can then be associated statistically with trait variation in symbiosis. Because of the exceedingly high level of SNP density, association mapping can approach the resolution of a single gene. These studies are being funded by the National Science Foundation.