Lack of Cross-Resistance of Imidazolinone-Resistant Cell Lines of Datura innoxia P. Mill. to Chlorsulfuron 1 Evidence for Separable Sites of Action on the Target Enzyme

• Published in: Plant physiology (Bethesda) Vol. 94; no. 3; pp. 1111 - 1115
• Main Authors: Saxena, Praveen K., King, John
• Format: Journal Article
• Language: English
• Published: 01.11.1990
• Subjects: Environmental and Stress Physiology
• ISSN: 0032-0889; 1532-2548

Two cell lines of Datura innoxia resistant to two imidazolinone herbicides, imazapyr and imazaquin, were isolated from mutagenized, predominantly haploid cell suspension cultures. Both of the resistant variants were >1000-fold more resistant than the wild-type to the two imidazolinones. The variant resistant to imazapyr showed cross-resistance to imazaquin and vice versa, but no cross-resistance to a structurally different inhibitor, chlorsulfuron, a sulfonylurea herbicide, was observed. The target enzyme, acetolactate synthase, extracted from imidazolinone-resistant cell lines was not inhibited by imazapyr or imazaquin but was sensitive to chlorsulfuron indicating separable sites of action for these inhibitors. The variation in resistance and cross-resistance of chlorsulfuron-resistant (PK Saxena, J King [1988] Plant Physiol 86: 863-867) and imidazolinone-resistant cell lines of Datura innoxia demonstrates the possibility of separate mutations of acetolactate synthase gene resulting in specific phenotypes.