A method for construction of bacterial artificial chromosome (BAC) contigs from a yeast artificial chromosome (YAC) physical map is described. An approximately 2 Mb contig, consisting of two large BAC contigs linked by a small YAC, has been assembled in the region around 80 cM of Arabidopsis thaliana chromosome 2. Clones from this contig will facilitate gene isolation in the region and can be used directly as substrates for DNA sequencing.