AN ORDERED ARABIDOPSIS-THALIANA MITOCHONDRIAL CDNA LIBRARY ON HIGH-DENSITY FILTERS ALLOWS RAPID SYSTEMATIC ANALYSIS OF PLANT GENE-EXPRESSION - A PILOT-STUDY

The availability of the complete sequence of a genome allows a systema tic analysis of its expression. Gene-specific variations of transcript ion levels and phenomena such as transcript processing and RNA editing require large numbers of clones to be examined. For the completely se quenced mitochondrial genome of Arabidopsis thaliana we adapted robot technology to identify and characterize expressed genes. A cDNA librar y of about 50 000 clones was constructed, robot-ordered into 384-well microtitre plates and spotted onto high-density filter membranes. Thes e filters permit the isolation of large numbers of specific cDNA clone s in a single hybridization step. The cox1, cox2 and cox3 genes were u sed to evaluate the feasibility and efficiency of this approach. A clu ster of RNA editing sites observed outside the cox3 coding region iden tifies a novel reading frame orf95 in higher plants with significant s imilarity to a subunit of respiratory chain complex II.