Use of Interfering RNAs to Identify Gene Function in Medicago Truncatula

University Of Minnesota-Twin Cities, Minneapolis MN

Investigators

Abstract

ABSTRACT Grain and forage legumes are grown on some 180 million Ha, or about 15% of the Earth's arable land and account for 27% of the world's primary crop production. Legumes are distinguished by their ability to form symbiotic associations with both rhizobial bacteria and mycorrhizal fungi. In the rhizobial association, the bacteria fix atmospheric nitrogen, providing the major source of biologically available nitrogen in the biosphere. The fungal symbiosis results in improved phosphorous acquisition. Nitrogen and phosphorus are the major mineral nutrients required for plant growth. Despite the agricultural and ecological importance of legumes, relatively little is known about the genes that are involved in the development of bacterial or fungal symbioses. The legume research community has developed many resources around the model legume Medicago truncatula. These include a large collection of ESTs (expressed sequence tags) from which many of the genes that are active in roots during symbiosis have been identified. Efficient transformation protocols have been developed and a genome sequencing project is ongoing. These resources and techniques will be combined with RNA interference (RNAi) technology to silence gene expression and identify genes involved in the plant-microbe symbioses. Analysis of sequence databases and gene expression studies will be used to identify genes that are possibly involved in symbiosis and 1,500 of these will be targeted for silencing via RNAi. Silencing will be carried out in transgenic roots and the effects on symbiosis will be examined. The results will be reported to the research community through a publicly available project web-site. The gene-targeting sequences will be made available at Clemson University Genomics Center without restriction to the research community in an easy to use, multifunctional vector. This research project integrates a variety of scientific fields including molecular biology, microbiology, plant biology and bioinformatics. The research also employs one of the latest and most powerful genomic technologies, RNAi, which is being used in a variety of applications from investigations into basic biology to the development of human therapeutics. The research team will introduce selected undergraduate students to many aspects the research which will expose them to the excitement of modern biological research. Additionally, collaborators at Gustavus Adolphus College, an undergraduate institution, will develop a laboratory course that follows the general protocols described in the research proposal. The materials and protocols that are developed through the research project are an excellent resource for this effort. The outcome of this effort will be the description of a series of experiences that undergraduate students in plant biology, plant molecular biology, or plant physiology can obtain in one semester course. Resources Generated: Publicly accessible database of root and symbiotic phenotypes and traits. Information on genomic experiments will be located at MtDB[http://medicago.org] , the Concensus Legume database www.legumes.org and [http://decifr.ccgb.umn.edu].