Arabidopsis gene knockout: phenotypes wanted

Gene knockout is considered to be a major component of the functional genom ics toolbox, and is aimed at revealing the function of genes discovered thr ough large-scale sequencing programs. In the past few years, several Arabid opsis populations mutagenized with insertion elements, such as the T-DNA of Agrobacterium or transposons, have been produced. These large populations are routinely screened for insertions into specific genes, allowing mass-is olation of knockout lines. Although many Arabidopsis knockouts have already been obtained, few of them have been reported to present informative pheno types that provide a direct clue to gene function. Although functional redu ndancy explains the lack of phenotypical alterations in some cases, ii also appears that many mutations are conditional and/or do not alter plant morp hology even in the presence of severe physiological defects. Consequently, gene knockout per se is not sufficient to assess gene function and must be integrated into a more global approach for determining biological functions .