|Plaisance, Kathryn - UNIVERSITY OF MINNESOTA|
|Anderson, Michael - OKLAHOMA STATE UNIVERSITY|
Submitted to: International Symposium on Weed & Crop Resistance to Herbicides Proceedings
Publication Type: Proceedings
Publication Acceptance Date: September 5, 1996
Publication Date: N/A
Technical Abstract: About 10 years ago, an atrazine-resistant biotype of Abutilon theophrasti was discovered in a maize field in Maryland (USA) that had been in continuous no-till maize production for six years and had been treated annually with simazine and/or atrazine. Compared to a susceptible Abutilon nbiotype from Minnesota (USA), the biotype from Maryland exhibited a tenfol increase in resistance to atrazine. Atrazine resistance was controlled by a single nuclear gene exhibiting partial dominance. Previous research established that atrazine resistance in the biotype from Maryland was due to an enhanced capacity to detoxify atrazine via glutathione conjugation. The enhanced rate of glutathione conjugation was not due to an increase in glutathione content, but instead was the result of elevated glutathione S-t hydroxyapatite, and S-hexylglutathione affinity chromatography was developed to purify total GST protein from leaf tissue of both resistant and susceptible biotypes. GST protein from both biotypes was purified approximately 250-fold with a yield of 35%. Total GST activity (measured with atrazine as substrate) and total GST protein were approximately five- and two-fold greater, respectively, in the resistant compared to the susceptible biotype. FPLC anion-exchange chromatography of affinity-purifi exhibiting activity with atrazine. However, the height of both peaks was approximately five-fold greater in the resistant biotype. It is concluded that resistance to atrazine in the Abutilon biotype from Maryland is due to enhanced levels of two GST isoforms selective for atrazine.