Fenoxaprop-P-Ethyl-Resistance And The Control Of Lolium Multiforum In Wheat Fields

Lolium multiforum is a herb of one year or more.It is suitable for growing in the south of the Yangtze River basin in China.There are artificial cultivars in Jiangxi,Hunan,Jiangsu,Zhejiang and other provinces and regions as the main herbage.In recent years,areas such as Henan,Jiangsu,and Shandong have gradually spread to wheat fields and become a kind of malignant,resistant weeds in wheat fields.fenoxaprop-P-ethyl belongs to a class of herbicides in acetyl-CoA carboxylase(ACCase)inhibitors.It is a class of herbicides with relatively single acting sites.This class of agents is always controlled.Wheat fields include important herbs such as multi-flowered ryegrass and many grasses.However,with the long-term and high-frequency use of such agents,the problem of drug resistance has become more and more serious.Treatment of agro-ecosystems with herbicides exerts strong selective pressure on weed plants,leading to the evolution of resistance to these herbicides.The resistance of ryegrass to fenoxaprozin is increasingly common in wheat fields in China,resulting in economic loss and loss of effective management methods.In order to gain insights into the level and progress of antibiotic resistance of Lolium multiflorum in the wheat fields of Henan,Jiangsu,Shaanxi,and Shandong in China,we investigated the effects of 50 Lolium multiflorum populations on fenoxaprofen.Resistance levels and genetic diversity and structure of representative 13 populations.The resistance levels of different ryegrass populations to fenoxaprop-p-methylcarbazone were clarified,and the genetic diversity,genetic structure and gene flow of different Lolium multiflorum populations were analyzed.Target enzyme gene sequence analysis of resistant populations revealed mutations in target sites,decreased activity of target enzymes,and rapid detection of target site mutations.Finally,a reasonable chemical control plan was made for the population of Lolium multiflorum with different resistance levels and mechanisms.The main results of this study are as follows:The susceptibility of 50 Lolium multiflorum populations to fenoxaprop-P-ethyl was determined using the whole-bioassay method.The results showed that the highest level of resistance was HZYC-6 population in Zhumadian,Henan,with an ED50 value of 2218.41 g a.i.ha-1.Compared with sensitive control population JNXW-2,the resistance was 99.39.The four populations of JLGY-2,JLGY-6,JLGY-7,JLGY-14 in Henan Province and the five populations of HZGX-1,HZGX-2,HZGX-3,HZYC-4 and HZYC-5 in Henan Province are also Benzoxazole had a higher degree of resistance(RI>20),and the relative resistance multiples were:27.92,27.96,27.47,24.57,40.13,24.06,54.59,24.36,27.40;relatively sensitive populations are:JNXW-1,JNXW-2,JHHY-2,JCJT-1,JYGY-1,JLGY-8,JLGY-9,JCWJ-4 eight populations;populations in other regions different degrees of relatively low levels of resistance have been generated.A total of 42 populations out of 50 populations were resistant to fenoxaflorin,indicating that the resistance of ryegrass to fenoxaforoxine in the studied area has already been more common.The analysis of neutral genetic variation using microsatellite markers showed that the genetic diversity of all populations was very high regardless of the level of resistance.Genetic variation is mainly distributed among individuals within the population,not between populations or sample counties.Bayesian clustering analysis provides evidence for the extensive pooling of populations between two genetic clusters or gene pools.The high degree of genetic diversity and mixing,as well as the poor differentiation among populations,strongly suggest the potential for the spread of resistance through gene flow,and the regulatory requirements that limit seed and pollen dispersion in Lolium multiflorum.After analyzing the gene sequences of the cloned target sequences of different resistance levels,mutations in four target sites were found in the resistant population of Zhumadian,Henan:Ile-1781-Leu,Ile-2041-Asn,Asp-2078-Gly,Cys-2088-Arg.The combination and frequency of these four target enzyme mutations in resistant Lolium multiflorum were:HZGX-2 population containing Ile-1781-Leu(13%),Ile-2041-Asn(7%),Asp-2078-Gly(7%);HZYC-4 population contains Ile-1781-Leu(93%),Ile-2041-Asn(7%);HZYC-5 population contains Ile-1781-Leu(72%),Ile-2041-Asn(16%),Cys-2088-Arg(12%);HZYC-6 population contains Ile-1781-Leu(88%),Asp-2078-Gly(42%).The target mutation is an important mechanism for the resistance of the Zhumadian-resistant population in Henan to the resistance to oxazidoxime.A molecular detection method for derivative cleaved amplified polymorphic sequences(dCAPS)was developed for the ACCase amino acid resistance D2078G,C2088R,I1781L,and I2041N mutations found in resistant populations.Mutation mutations are detected quickly and accurately.Using the CAPS and dCAPS techniques established in this chapter,the resistance mutations in the HZGX-1,HZGX-2,HZYC-4,HZYC-5,and HZYC-6 populations of the anti-zooxazole triterpenoid ryegrass were tested.Of the 100 strains of HZGX-1 weeds tested,100 strains were resistant to Ile-1781-Leu mutation and 6 strains were Asp-2078-Gly.The I1781L mutation occurred in 88 Lolium multiflorum targets in the results of the resistant HZYC-6 population,and 2078 mutations(D2078G)were detected in 42 Lolium multiflorum.Among the resistant HZGX-2 populations,13 of 100(11781L)mutants were detected in Lolium multiflorum,7 of them contained 2078 mutations(D2078G),and 7 of 2041 were found to contain isoleucine.The mutation was asparagine(12041N).In the resistant HZYC-4 population,93 strains were found to have the 11781L mutation and the codon ATA mutation was caused by the CTA;7 strains containing the 2041 isoleucine were all mutated to asparagine(12041N).Of the 100 samples of HZYC-5 population,72 strains of Lolium multiflorum had the I1781L mutation,16 of the 2041 isoleucines were all mutated to asparagine(12041N),and 12 Lolium multiflorum plants contained the C2088R mutation.These results are consistent with the sequencing results of the gene sequences.The study of the JLGY-6 enzyme activity in the Jiangsu resistant population revealed that the sensitivity reduction was 9.58 times that of the sensitive population.The concentration of the agent that inhibited 50%of the enzyme activity of the resistant population of oxazolyl-trimizole,ie,the IC50 value was 24.33±4.30 ?M,while the IC50 value of the sensitive population was 2.47±0.61 ?M,and the relative resistance multiple was 9.85.The different activity ratios of ACCase-resistant and wild-type Lolium multiflorum ACCase treated with fenoxaflorin showed that the change of sensitivity of ACCasse to oxazolyoxime was JLGY-6 population of ryegrass.One of the important mechanisms for the resistance to oxazolyoxime is drug resistance.In the analysis of the target sequences of the resistant population of Lolium multiflorum in Jiangsu Province,no changes were found in the target loci.We analyzed that due to genetic evolutionary reasons,a large number of cases where resistance mutations could be detected have not yet occurred.It is also possible that the amount is still extremely low and difficult to detect.In short,resistance mutations have not yet been found in our experimental materials,nor is it currently the main factor in the resistance of Lolium multiflorum in Jiangsu Province.In the study of the expression levels of sensitive and resistant target genes,there was no significant difference in the expression of resistant and susceptible populations.In addition,the Jiangsu population was resistant to other agents other than oxazolyoxalin,such as other ACCase inhibitors such as quizalofop,flupirtine,clodinafop,clethodim,acridine and oxazoline.These herbicides are sensitive to oxalates,and herbicides such as ALS and photosynthetic inhibitors do not produce resistance.This multi-faceted mutual support shows that the main reason for the resistance of the resistant population of Lolium multiflorum in Jiangsu Province is caused by the decrease of target enzyme activity,and other aspects of resistance factors have not evolved to or are not the main factors.The population of Lolium multiflorum in Jiangsu Province was only resistant to fenoxaprop-P-ethyl and it was still sensitive to other pesticides.It was also better controlled,but the resistant population represented by the Zhumadian area in Henan Province was highly resistant to other species.Herbicides with the same mechanism of action also produce varying degrees of cross-resistance.This study used the Zhumadian resistant population in Henan Province to study the control of resistant Lolium multiflorum.First,we found that the resistant population HZYC-6 had high resistance to AOPP herbicides,flupirtine and quizalofop,and the relative resistance multiples were 13.85 and 25.96 fold respectively;Moderate resistance to these agents such as clodinafop-propenyl ester and acridine,their relative resistance multiples were 8.84 and 8.77 times,respectively;low resistance to clethodim and oxazoline oxalate,resistance times were 3.25 and 3.65,respectively Times.This indicates that the HZYC-6 high-resistance population of anti-zooxazolyoxazel has already produced different degrees of resistance to ACCase inhibitors.This type of ACCase inhibitor herbicide is no longer suitable for the control of Lolium multiflorum.The ED50 values of the HZYC-6 population pair were 8.06 g ai ha-1,1.66 g ai ha-1,5.81 g ai ha-1,3.71 g ai ha-1,and 2.67 g ai ha-1,respectively,and their ED90 values were all less than The recommended doses of the respective agents in the field,so these methods are effective for controlling ryegrass.The ED50 values for the organophosphorus inhibitors glyphosate isopropylamine salt,substituted urea chlorotoluron,amicarbazone,and flufenacet were 597.26 g ai ha-1,282.94 g ai ha-1,21.77 g ai ha-1.The relative resistance multiples of and 41.15 g ai ha-1 were 1.82,1.55,1.26,and 0.91 times,and their ED90 was less than the field-preferred dose of their respective pesticides,which had better results in controlling Lolium multiforum.In addition,we screened the two plants with good resistance against Pteridium forensic in the laboratory to screen for the virulentity of the resistant Lolium multiflorum,Clofibrate and Fluopyram compounding agent(1:2),Clofibromide/Betachlor Complex(1:1.7)has better control effect on fresh weight of ryegrass in wheat fields.Within the range of dose setting,the control effect of Lolium multiflorum is both effective.Above 90%and safe for wheat,it provides a good selection of pharmaceutical formulations for the control of resistant Lolium multiflorum.