Study on Enzymatic Inhibition of Acetolactate Synthase from Maize (Zea mays L. ) by Chlorsulfuron and Tribenuron-methyl

The relative sensitivity of maize (Zea mays L.) varieties Nongda108 and Nongda3138 to sulfonylurea herbicide chlorsulfuron and tribenuron methyl was studied by using maize main root length in sand culture. Results showed that Nongda3138 had higher tolerance to chlorsulfuron and tribenuron methyl than Nongda108. Chlorsulfuron had stronger growth inhibitory effect on maize varieties Nongda108 and Nongda3138 than tribenuron methyl. Study on target enzyme of sulfonylurea herbicide acetolactate synthase (ALS) showed that chlorsulfuron and tribenuron methyl inhibited ALS in vitro violently and they were non competitive inhibitors to ALS. At the same concentration of inhibitors, chlorsulfuron had stronger inhibitory effect on ALS activity than tribenuron methyl. Lower level of chlorsulfuron and tribenuron methyl had no inhibitory effect on ALS activity in vivo, and the inhibitory effect on ALS activity only occurred in the condition of high concentration of chlorsulfuron and tribenuron methyl in vivo.