ALTERATION OF BETA-TUBULIN IN NICOTIANA-PLUMBAGINIFOLIA CONFERS RESISTANCE TO AMIPROPHOS-METHYL

A Nicotiana plumbaginifolia plant (apm5(r)) resistant to amiprophos-me thyl (APM), a phosphoroamide herbicide, was isolated from protoplasts prepared from leaves of haploid plants. Genetic analysis revealed that the resistance is coded for by a dominant nuclear mutation and is ass ociated with the increased stability of cortical microtubules. Two-dim ensional polyacrylamide-gel electrophoresis, combined with immunoblott ing using anti-tubulin monoclonal antibodies, showed that part of the beta-tubulin in the resistant plant possessed lower isoelectric points than the beta-tubulin of susceptible wild-type plants. These results provide evidence that the resistance to APM is associated with a mutat ion in a beta-tubulin gene. The APM-resistant line showed cross-resist ance to trifluralin, a dinitroaniline herbicide, suggesting a common m echanism of resistance between these two classes of herbicides.