|Samac, Deborah - Debby|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/7/2001
Publication Date: N/A
Technical Abstract: Medicago truncatula has become a useful model plant for molecular studies of nitrogen-fixing symbiotic interactions. This species is also suitable to investigate plant responses to different pathogens. Our aim is to characterize legume genes involved in responses to microbes. As of April 2001, >50,000 5' sequences have been obtained from cDNA libraries spanning various stages of vegetative development. To identify genes induced in roots, ESTs were obtained from libraries generated after inoculation with the nitrogen-fixing bacterium Sinorhizobium, the mycorrhizal fungus Glomus, or the root rot-inducing oomycete Phytophthora or its glucan elicitor. All ESTs are in GenBank and have been used (together with other public data) to construct a gene index (MtGI) that represents a minimally redundant set of sequences. MtGI groups ESTs into tentative gene clusters (TCs) according to sequence overlap (http://www.tigr.org//tdb/mtgi). MtGI also allows assignment of tentative function to expressed genes, based on BLAST results, and indicates expression patterns of highly expressed genes, based on tissue of origin of the ESTs. Analysis reveals many examples of tissue- specific patterns of expression. We will establish a unigene set of cDNA clones to investigate the genome-wide patterns of gene expression using hybridization of probes to DNA microarrays. As a first step, we have assembled a small scale array of ~1,000 cDNA clones ('kiloclone set'), that contains positive and negative controls and clones of known tissue-specific patterns, as well as clones with putatively interesting function. Hybridization experiments to date have assessed differences in gene expression during the early steps of the symbiotic process or during pathogenic interactions, compared to uninoculated plants.