Plant & Animal Genome IX Conference

Poster: Sequencing & EST
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EXPRESSION ANALYSIS OF MEDICAGO TRUNCATULA ESTS INVOLVED IN PLANT-MICROBE INTERACTIONS USING MACRO- AND MICROARRAYS

¹ Department of Agronomy and Plant Genetics, University of Minnesota, 411 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN 55108, USA

² Department of Plant Biology, University of Minnesota, 220 BioScience Building, 1445 Gortner Ave., St. Paul, MN 55108, USA

³ The Institute for Genomic Research, 9712 Medical Center Drive, Rockville, MD 20850, USA

⁴ Department of Plant Pathology, University of Minnesota, 495 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN 55108, USA

⁵USDA-ARS, Plant Science Research Unit, St. Paul, MN 55108, USA

Due to the ability of forming both symbiotic and pathogenic associations, a self-pollinated diploid legume Medicago truncatula has been selected as a model plant species to study the functional genomics of plant-microbe interactions. 5`-EST sequencing from twelve M. truncatula cDNA libraries has resulted in over 33,000 entries. To initiate high-throughput expression profiling of these ESTs, pilot sets of clones were spotted onto nylon membranes (macroarrays) or glass slides (microarrays), and analyzed by hybridization with various cDNA probes. These assays have focused on two aspects of plant-microbe interactions: symbiotic relations with N₂-fixing bacterium Sinorhizobium meliloti, and plant interactions with pathogenic fungi Phytophthora medicaginis and Colletotrichum trifolii. Macroarray hybridization revealed dozens of plant genes with altered expression levels as a result of plant-microbe interaction. A pilot Kiloclone Microarray containing 1000 clones was tested with several cDNA probes to optimize microarray hybridization procedure and to characterize microbe-elicited tissues. Project sequences, along with other publically available data, have been used to construct a Gene Index (www.tigr.org) that represents a minimally redundant set of M.truncatula sequences. Analysis of EST frequencies in the different libraries reveals numerous examples of a tissue-specific pattern of gene expression. The Gene Index will become a platform for selecting and microarray-based expression profiling of an entire non-redundant set of M.truncatula ESTs - a Unigene Set. The research was supported by the NSF grant # DBI 9872664.