USING ARABIDOPSIS AND RICE CONSERVED EST FOR COMPARATIVE MAPPING

Laboratoire de Physiologie et Biologie Moleculaire des Plantes, UMR 5545 CNRS, University of Perpignan, 66860 Perpignan, France

We report progress in a an attempt to use the Arabidopsis genome information for transferring it to cultivated crops. We have started a comparison between Arabidopsis and Rice EST. We set up a threshold BLAST score of 400 and selected about 350 Arabidopsis EST with strong homology with Rice EST. This first screening was further improved by analysing EST contigs and reconstructing a number of cDNA clones. We observed that most of the selected EST belong to small gene families coding essentially for housekeeping proteins. More than 150 have been mapped on the Arabidopsis genome, either directly, essentially using a 3-D pooling strategy on the CIC YAC library, or during genomic sequencing. Amongst the best scoring rice EST, more than 60 have already been mapped in this species. Comparison of the two Arabidopsis and Rice maps provides very few evidence for syntenic blocks between these two distant genomes. The high conservation of these genes between Rice and Arabidopsis suggested that they should also be conserved between Arabidopsis and other crops and that they can constitue a set of universal anchored probes which would facilitate comparative mapping. Two sets of 96 clones have been distributed to participants of the European Programme EuDicotMap for mapping in different crops (Brassica napus, potato, pea, alfalfa, sugar beet, sunflower, and almond tree). Preliminary evidence indicate that a majority of the distributed clones detect some polymorphisms in the studied crops. Progress and difficulties in this comparative mapping work will be discussed.