The Chemical Control Technology Of Japanese Foxtail(Alopecurus Japonicus) Resistant To Fenoxaprop-P-ethyl With Mutations At Different Codon Position In Wheat Fields

In the wheat fields of the middle and lower reaches of the Yangtze River in China,the resistance of Alopecurus japonicas,a grass weed,to fenoxaprop-P-ethyl,the main herbicide in the wheat field,has been very serious,which poses a serious threat to the safe production of wheat.According to reports,six amino acid mutations at five sites have been found in the CT region of Acetyl CoA carboxylase(ACCase)gene of the resistant Alopecurus japonicas.In order to systematically study the chemical control techniques of the resistant Alopecurus japonicas with different site mutations in wheat fields,we first screened out the herbicides that can effectively control the resistant Alopecurus japonicas with mutations at different codon position in wheat field by whole-plant bioassay;secondly,the synergistic effect and synergistic mechanism of adjuvant on herbicides were studied,and the synergism combination of herbicide+adjuvant which could effectively control resistant Alopecurus japonicas in wheat field was screened out;finally,suitable herbicides were selected for compounding,and the formulation ratio of the three compounding agents was selected,the field efficacy test was carried out to test the toxicity of the compounding agent to other weeds in the wheat field and the safety of the compounding agent to wheat.In addition,this paper also explored the use of RNA interference technology to prevent the resistant Alopecurus japonicas.Detailed results are as follows:The whole plant bioassay was used to study the sensitivity of Alopecurus japonicus with mutations at different codon position to relational herbicides(including herbicides frequently used to control grass weeds in wheat field and other crop field,and new herbicides used to control grass weeds),the safety of non-wheat field herbicides on wheat(Zhenmai 9)was also studied.The results showed that foliar-applied herbicides such as isoproturon,chlorotoluron,pyroxsulam,mesosulfuron-methyl,soil-applied herbicides such as isoproturon,chlorotoluron,new herbicides such as huanbifucaotong,flufenacet,terbutryn(all used in wheat field)had great inhibition effect on all resistant Alopecurus japonicas populations,besides,diflufenican had great inhibition effect on the resistant population with mutation at 2041 codon position.Among non-wheat herbicides,soil-applied herbicides such as metazachlor,pretilachlor,oxadiazon,trifluralin,and oxyfluorfen had great inhibitory effect on the resistant Alopecurus japonicas with mutation at different codon positions,but because of the low selectivity index for the wheat tested,these herbicides could not be applied to control resistant Alopecurus japonicas in wheat fields.The whole plant bioassay was used to study the best synergistic dose of three adjuvants Jijian,Anngro,and Silwet 806 on isoproturon,chlorotoluron and mesosulfuron-methyl controlling the resistant Alopecurus japonicus,the effect of reduction and the effect of mixture of adjuvants and herbicides on wheat safety.The results show that Silwet 806 had the most obvious effect on the reduction of isoproturon and chlorotoluron at the optimal synergistic dose,Jijian and Anngro had a certain degree of reduction effect on isoproturon and chlorotoluron,and none of the three adjuvants can increase the control effect on the resistant Alopecurus japonicus to a very significant level,isoproturon+Silwet 806 and chlortoluron+Silwet 806 are the best synergistic combination,but Silwet 806 mixed with isoproturon significantly increased the inhibition rate of fresh weight of wheat seedlings tested and decreased the safety of the wheat tested.The study on synergism mechanism of Silwet 806 revealed that after adding Silwet 806,the surface tension of the chlortoluron solution was significantly lower,the contact angle of chlortoluron solution and leaf was significantly smaller,the dry duration of chlortoluron solution on leaf was significantly shorter,the rentention of chlortoluron solution on leaf increased significantly,and compared with the single dose of chlorotoluron,the chlorophyll content in resistant Alopecurus japonicus treatment with mixture of Silwet 806 and chlorotoluron decreased significantly after 5 days.In order to improve the control effect of resistant Alopecurus japonicus,prevent their resistance from aggravating and producing multiple resistance,and expand the weed killing spectrum,and effectively control weeds in wheat field with resistant Alopecurus japonicas with mutations at different codon position as dominant species,on the basis of single-dose screening,the indoor formulation screening tests of huanbifucaotong+chlortoluron,mesosulfuron-methyl+isoproturon and pyroxsulam+ isoproturon were carried out,and the effects of the three formulations were evaluated by the equivalent line method.The results showed that all the three formulations had good synergistic effect on the resistant Alopecurus japonicas,finally,the optimum ratio of huanbifucaotong:chlorotoluron was 1:9,mesosulfuron-methyl:isoproturon was 1:14,and pyroxsulam:isoproturon was 1:74.The toxicity of three formulations to main grass weeds and broad-leaved weeds in wheat field was tested under the condition of simulated field efficacy test.The results showed that the compound of huanbifucaotong and chlorotoluron(1:9)at the dosage of 720-840g a.i./ha,the compound of mesosulfuron-methyl and isoproturon(1:14)at the dosage of 600-720g a.i./ha and the compound of pyroxsulam and isoproturon(1:74)at the dosage of 600-700g a.i./ha could effectively prevent all resistant Alopecurus japonicas populations,multi-resistant Alopecurus aequalis,Beckmannia syzigachne and Lolium multiflorum resistant to fenoxaprop-P-ethyl,sensitive Stellaria media,Geranium carolinianum and Descurainia sophia,and three formulations are safe to the wheat tested,in addition,the compound of huanbifucaotong+chlorotoluron and the compound of mesosulfuron-methyl+isoproturon had great control effect on Galium aparine,and all three compounds had an ordinary control effect on Vicia gigantea.Based on the theory of RNA interference,we selected virus-mediated gene silencing(VIGS)as the transfection method and PDS gene as the target gene,then we cloned the conserved region of Alopecurus japonicas PDS gene and selected partial fragment as the interference fragment to construct the VIGS-RNAi carrier of Alopecurus japonicas PDS gene with BSMV as carrier skeleton,and we also studied the phenotypic changes of new leaves of the resistant Alopecurus japonicas plants after inoculation with related carrier.The results showed that the albinism of new leaves was observed in wheat plants inoculated with VIGS-RNAi carrier of wheat PDS gene,while no albinism was observed in the resistant Alopecurus japonicas plants inoculated with both VIGS-RNAi carrier of wheat PDS gene and VIGS-RNAi carrier of Alopecurus japonicas PDS gene.