Dinitroaniline herbicide-resistant transgenic tobacco plants generated by co-overexpression of a mutant alpha-tubulin and a beta-tubulin

Dinitroaniline herbicides are used for the selective control of weeds in ar able crops. Dinitroaniline herbicide resistance in the invasive weed gooseg rass was previously shown to stem from a spontaneous mutation in an alpha-t ubulin gene. We transformed and regenerated tobacco plants with an alpha/be ta-tubulin double gene construct containing the mutant a-tubulin gene and s howed that expression of this construct confers a stably inherited dinitroa niline-resistant phenotype in tobacco. In all transformed lines, the transg ene alpha- and beta-tubulins increased the cytoplasmic pool of tubulin appr oximately 1.5-fold while repressing endogenous alpha- and beta-tubulin synt hesis by up to 45% in some tissues. Transgene alpha- and beta-tubulin were overexpressed in every plant tissue analyzed and comprised approximately 66 % of the total tubulin in these tissues. Immunolocalization studies reveale d that transgene alpha- and beta-tubulins were incorporated into all four m icrotubule arrays, indicating that they are functional. The majority of the alpha/beta-tubulin pools are encoded by the transgenes, which implies that the mutant alpha-tubulin and the beta-tubulin can perform the majority, if not all, of the roles of microtubules in both juvenile and adult tobacco p lants.