Insights Into Profiling Of Resistance Mechanism Of Abutilon Theophrasti To Atrazine

Abutilon theophrasti is the main broad-leaved weed in corn fields in China.It is widely distributed in various provinces China,and its control is difficult.Atrazine,a triazine herbicide,is the main chemical used in the control of abutilon in corn fields in my country.The long-term and frequent use of atrazine has significantly reduced the control effect of atrazine on abutilon in corn fields,which will seriously affect the corn yield in the long run.This study took 68 abutilon populations collected from Liaoning Province as the research object,and carried out research from the aspects of drug resistance level,target and non-target drug resistance mechanism,etc.,in order to provide theoretical guidance for delaying the development of abutilon drug resistance and scientific and rational drug use.The drug resistance level of atrazine in 68 abutilon populations was determined by the whole-plant dose-response method.The results indicated that in 2019,27 abutilon populations had different levels of resistance to atrazine,and the GR₅₀ranged from 65.10 to367.95 g a.i./hm²,the median value is 161.88 g a.i./hm²,the RI value is 3.64～20.56,7high-resistance populations,the occurrence frequency is 23.33%,17 moderately resistant populations,the occurrence frequency is 56.67%,3 resistant populations,occurrence frequency 10%.Among them,the LN10 population collected from Faku County,Shenyang City had the highest level of drug resistance;in 2020,36 abutilon populations developed different levels of resistance to atrazine,with a GR₅₀of 132.36-372.50 g a.i./hm²,with a median value of 182.87 g a.i./hm²,RI value is 7.64～21.50,there are 25 high-resistance populations with a frequency of 65.79%,11 medium-resistant populations with a frequency of 28.95%,and 0 resistant populations with a frequency of 0%,which were collected from Panjin The LN63 population in the city had the highest level of drug resistance.It shows that the Liaoning Province abutilon has developed resistance to atrazine,and the resistance level is increasing year by year.Amplification and sequencing of the conserved fragment of the psb A gene of Abutilon.The results showed that the 264-amino acid of the abbreviated abbreviated abbreviated to atrazine population was serine（AGT）and no target mutation was found.Therefore,it was inferred that atrazine was resistant to atrazine.The occurrence of drug resistance is independent of target site mutation.The effects of P450s inhibitor malathion and GSTs inhibitor piperonyl butoxide on the resistance level of abutilon population were studied.The data indicated that the GR₅₀ratios of the resistant populations LN10,LN25,LN31 and LN63 before and after application were:1.04,1.03,1.02 and 1.06,respectively,indicating that malathion had no effect on the resistance level of abutilon;It can significantly reduce the resistance level of atrazine in the abutilon population.The GR₅₀ratios of the drug-resistant populations LN10,LN25,LN31and LN63 before and after application are:4.05,2.77,2.21 and 2.06,respectively.In addition,by measuring the changes of GSTs activity of different drug-resistant populations before and after application,it was found that the GSTs activity of weeds was induced,and the GSTs activity of drug-resistant abutilon populations was always higher than that of sensitive populations in the same period,especially after treatment.It is inferred that the resistance of atrazine to atrazine is related to the induction of GSTs activity.The differences in atrazine absorption and metabolism in the resistant populations were evaluated by high performance liquid chromatography-triple quadrupole liquid chromatography-mass spectrometry（HPLC-MS/MS）.The results showed that there was no significant difference in the absorption rate of atrazine between LN63 and LN43,but after atrazine treatment,the metabolic rate of atrazine in the resistant population LN63 was significantly higher than that in the sensitive population.The combined treatment of piperonyl butoxide and atrazine could significantly slow down the metabolic rate of atrazine in resistant populations.After spraying with piperonyl butoxide,the metabolic rates of atrazine in the resistant population LN63 and the susceptible population LN43 were 40.76%and 18.23%,respectively,after 7 days of atrazine treatment.This indicated that the development of atrazine resistance in abutilon may be related to the enhanced metabolic capacity of the resistant populations.