Plant & Animal Genome IX Conference Plant & Animal Genome IX Conference
Poster: Sequencing & EST
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In addition to providing an efficient method for gene discovery, EST data sets can provide information on gene expression. This aspect of EST analysis is based on the rationale that if a gene is highly transcribed, (leading to high mRNA levels), then cDNAs corresponding to the mRNA will be abundant in a cDNA library made from the tissue in which the gene is expressed. After random sequencing of a large number of clones from the cDNA library, simply counting the number of ESTs that correspond to the mRNA for a gene will provide an estimate of the abundance of the mRNA in the original population. Such electronic Northerns were performed for the root (R) and aerial part (A) of drought stressed (S) and controled (C) maritime pine (Pinus pinaster) seedlings, each profil being the result of sequencing several hundreds of ESTs taken at random from each of the 4 libraries: AC, AS, RC, RS. After the first 100 EST were obtained for each library, the most abundant ESTs (ribosomal proteins, RuBisCo-ssu, Lp8, Cabs,metallothionein) were identified and removed (using hybridization on macroarray) from further sequencing steps, allowing a higher proportion of different ESTs to be sequenced. This screening procedure allows to eliminate 144 clones (82 AC, 40 AS, 15 RC, 7 RS). A total of 2064 ESTs were finally obtained (366 AC, 564 AS, 571 RC, 563 RS). Here we present and discuss the results of this experiment in terms of differential gene expression.