Kanamycin resistance in plants: an unexpected trait controlled by a potentially multifaceted gene

Ayalew Mentewab and C. Neal Stewart Jr recently showed that an Arabidopsis kanamycin resistance gene encodes an ATP binding cassette (ABC) transporter. This Atwbc19 protein is hypothesized to prevent ribosome inactivation by translocating kanamycin into the vacuole. Because ABC transporters often recognize multiple exogenous substrates, overexpression of Atwbc19 can result in the accumulation of unexpected compounds in transgenic plants. Another potential safety issue associated with this gene is horizontal gene transfer. Thus, commercial applications are likely to be limited to methods that allow removal of the selectable marker from the transgenic plant genome.