To date, the only report of a genome-wide collection of disruption mutants is for the unicellular budding yeast Saccharomyces cerevisiae. Such a collection of mutants enables the functional analysis of the full gene complement of an organism, but the creation of a similar collection for eukaryotes has been hampered by the efficiency of homologous recombination. In the August 1 Science, José M. Alonso and colleagues at The Salk Institute of Biological Studies report the generation of a genome-wide, sequence-indexed Arabidopsis thaliana insertion mutant collection. Using their mutant database, the authors identified a new family of proteins involved in the ethylene pathway (Science, 301:653-657, August 1, 2003).

Alonso et al. used selected Agrobacterium transferred DNA (T-DNA) to generate about 150,000 transformed A. thaliana plants. The genomic location of each integration event was mapped—identifying 88,122 T-DNA/genome junction sequences, and confirming the generation of mutation in 21,799 of the 29,454...