Poster: Genomic & proteomic resources

Abs # 883: Development of reverse and forward genetic resources for the model legume Medicago truncatula

Presenter:	Wang, Hong-Liang , hlwang@noble.org
Authors	Wang, Hong-Liang  (A)   Li, Guangming  (A)   Versaw, Wayne K. (B)   Shin, Hwa-Soo  (A)   Dixon, Richard A. (A)   Chen, Rujin  (A)
Affiliations:	(A): The Samuel Roberts Noble Foundation (B): Current Addres: Texas A&M University

Medicago truncatula (ecotype Jemalong A17) has emerged as a model legume species for functional genomics studies of plant developmental processes that are unique to legumes such as legume-rhizobial symbiotic interactions. To complement the functional genomics resources developed for this species, we are generating a large deletion mutant population using fast neutron mutagenesis. Currently, we have generated a M₂ population derived from approximately 17,000 M₁ plants and collected leaf tissues from M₂ progenies of ~1900 M₁ plants. DNA samples will be extracted from these leaf tissues using a three-dimensional pooling strategy for a high-throughput purpose. These DNA samples will serve as templates to optimize a PCR-based screening method for detection of deletion mutations in selected genes. On the other hand, M2 mutant lines displaying visible and interesting phenotypes are subjected to forward genetics studies. We are investigating a sterile M2 line that is also defective in compound leaf architecture. The phenotypes of F1 plants of a backcross with the wild type are normal, indicating that the mutation is recessive. Preliminary sequencing results suggest that M. truncatula orthologs of pea Unifoliata and Stamina pistilloida, two genes crucial for the compound leaf development in pea, are not disrupted in the mutant. To clone the responsible gene(s) a mapping population has been constructed by crossing the mutant with a mapping line Jemalong A20 and segregation analyses will be carried out in the F2 population. While the genetic analysis of compound leaf architecture has been undertaken in pea and tomato, M. truncatula would serve as a new model since the gene space of its relatively compact genome will be completely sequenced in the next three years.