Expression of a rice <Emphasis Type="Italic">CYP81A6</Emphasis> gene confers tolerance to bentazon and sulfonylurea herbicides in both <Emphasis Type="Italic">Arabidopsis</Emphasis> and tobacco

Bentazon and sulfonylurea are two different classes of herbicides that have been widely used to kill broad-leaf weeds in rice fields. A cytochrome P450 gene, CYP81A6, encoding a monooxygenase has been previously identified to confer resistance to these two classes of herbicides in wild-type rice. In this study, we introduced the rice CYP81A6 gene into Arabidopsis and tobacco plants to test the possibility of engineering tolerance to these two types of herbicides in other susceptible plants. Arabidopsis and tobacco plants expressing CYP81A6 showed tolerance to both bentazon and bensulfuron-methyl (BSM), a widely applied sulfonylurea herbicide. The optimal concentrations of bentazon and BSM for the selection of CYP81A6 transgenic plants were also determined. In addition, we also demonstrated that CYP81A6 can be used as a selection marker to effectively screen for positive transgenic Arabidopsis plants. The selection efficiency of CYP81A6 was comparable to that of the bar gene in Arabidopsis. These results suggest that CYP81A6 can not only be used to produce transgenic plants tolerant to both bentazon and sulfonylureas, but that it can also be used as a novel plant-derived selection marker in plant transformation.