Medicago truncatula

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Medicago truncatula is the pre-eminent model plant for studying symbiotic relationships between plants and their symbiotic microbes (i.e. rhizobial bacteria and mycorrhizal fungi). Attributes of M. truncatula that make it desirable as an experimental system include itsannual habit, diploid and self fertile nature, abundant natural variation, and close phylogenetic relationship to many crop legume species.

Thus, this model leguminous plant has great potential for both basic and applied biological studies. Over the past decade several research groups have developed the tools and infrastructure necessary for basic research
in M. truncatula, including efficient transformation systems , high-throughput systems for forward and reverse genetics including insertional mutagenesis, RNAi, and TILLING, well-characterized cytogenetics, and a collaborative research network (

Research efforts on M. truncatula encompass a broad range of issues in plant biology, from studies of population biology and resistance genes, to the molecular basis of symbiotic interactions and micronutrient homeostasis. Critical to continued and accelerated progress in these biological investigations is the parallel development of tools for genome analysis, which presently include in excess of 226,900 ESTs in the public domain, a complete physical map with 20X coverage and public microarray resources to measure expression of a limited fraction of the predicted genes via 6,000 cDNA and 16,000 70mer oligonucleotide array sets. Most important of all, there is an ongoing whole genome sequencing effort that, as of July 2006, has released to the public domain about 180Mb of gene rich regions. A completed draft sequence of the gene-rich genome is expected by the end of 2006 . Various national and international programs have collaborated to characterize the genome of M. truncatula at the transcript , protein, and whole genome sequence levels.

The goal of the Wisconsin Medicago Group is to extend this work and apply innovative new technologies to help convert this sequence data into a more complete understanding of the essential signaling processes occurring at the plasma membrane.

Just as different plants are variously useful for basic research, there is also great variability in the quality and value of technologies used to study their genomes. Transcriptome profiling is one example, since recent studies suggest that gene only arrays using cDNA or incomplete genome sequence cannot measure RNA expressed from intergenic or antisense genic domains. Proteomic technologies are even farther away from perfection since even under the best circumstances, only a few thousand proteins can be readily analyzed within a few days, representing the most abundant 10% (i.e., 1000-2000) proteins. Phenotypes are often assessed by simple visual inspection or ruler measurements, yet more sophisticated morphometric technologies can now be employed.

This project is upported by funds provided by the National Science Foundation through the Plant Genome Program, Award Number 0701846 for the project entitled "An Interdisciplinary Approach to Deciphering the Molecular Dialogue between the Plasma Membrane and Cytoplasm of Medicago truncatula".