Previous studies have documented the occurrence of glyphosate-resistant （GR） goosegrass （Eleusine indica （L.） Gaertn.） and, in at least some cases, resistance is due to an altered target site. Research was perfo...Previous studies have documented the occurrence of glyphosate-resistant （GR） goosegrass （Eleusine indica （L.） Gaertn.） and, in at least some cases, resistance is due to an altered target site. Research was performed to determine if an altered target site was responsible for GR in a Tennessee, United States goosegrass population （TennGR）. DNA sequencing revealed a mutation in TennGR plants conferring the Prol06Ser 5-enolpyruvylshikimate-3-phosphate synthase （EPSPS） substitution previously identified in other GR populations. F2 populations were derived from TennGR plants crossed with plants from a glyphosate-susceptible population （TennGS） and analyzed for their response to glyphosate and genotyped at the EPSPS locus. Plants from the F2 populations segregated 1：2：1 sensitive：intermediate：resistant in response to a selec- tive dose of glyphosate, and these responses co-segregated with the EPSPS genotypes （PP106, PS106, and SS106）. To separately investigate the effect of the Prol06Ser substitution on GR, glyphosate dose-response curves and 50% effective dose （EDso） values were compared among the three genotypes and the two parental populations. The SS106 genotype was 3.4-fold resistant relative to the PP106 genotype, identical to the resistance level obtained when comparing the resistant and susceptible parental populations. We conclude that the mutation conferring a Prol06Ser EPSPS mutation is solely responsible for GR in the TennGR goosegrass population.展开更多
Through introducing the analytical problem of the plate with convection into the solution of the transient heat conduction thermal stress field model of the elastic plate, the stress reduction factor is presented expl...Through introducing the analytical problem of the plate with convection into the solution of the transient heat conduction thermal stress field model of the elastic plate, the stress reduction factor is presented explicitly in its dimensionless form. A new stress reduction factor is introduced for the purpose of comparison. The proper- ties and appropriate conditions of the stress reduction factor, the first and second ther- mal shock resistance （TSR） parameters for the high and low Biot numbers, respectively, and the approximation formulas for the intermediate Blot number-interval are discussed. To investigate the TSR of ceramics more accurately, it is recommended to combine the heat transfer theory with the theory of thermoelasticity or fracture mechanics or use a numerical method. The critical rupture temperature difference and the critical rup- ture dimensionless time can be used to characterize the TSR of ceramics intuitively and legibly.展开更多
The effects of mechanical boundary conditions, often encountered in thermalstructural engineering, on the thermal shock resistance（TSR） of ultra-high temperature ceramics（UHTCs） are studied by investigating the TS...The effects of mechanical boundary conditions, often encountered in thermalstructural engineering, on the thermal shock resistance（TSR） of ultra-high temperature ceramics（UHTCs） are studied by investigating the TSR of a UHTC plate with various types of constraints under the first, second, and third type of thermal boundary conditions. The TSR of UHTCs is strongly dependent on the heat transfer modes and severity of the thermal environments. Constraining the displacement of the lower surface in the thickness direction can significantly decrease the TSR of the UHTC plate, which is subject to the thermal shock at the upper surface. In contrast, the TSR of the UHTC plate with simply supported edges or clamped edges around the lower surface is much better.展开更多
The rice stem borer(RSB),Chilo suppressalis,a notorious rice pest in China,has evolved a high resistance level to commonly used insecticides.Tetraniliprole,a new anthranilic diamide insecticide,effectively controls mu...The rice stem borer(RSB),Chilo suppressalis,a notorious rice pest in China,has evolved a high resistance level to commonly used insecticides.Tetraniliprole,a new anthranilic diamide insecticide,effectively controls multiple pests,including RSB.However,the potential resistance risk of RSB to tetraniliprole is still unknown.In this study,the tetraniliprole-selection(Tet-R)strain was obtained through 10 continuous generations of selection with tetraniliprole 30%lethal concentration(LC_(30)).The realized heritability(h^(2))of the Tet-R strain was 0.387,indicating that resistance of RSB to tetraniliprole developed rapidly under the continuous selection of tetraniliprole.The Tet-R strain had a high fitness cost(relative fitness=0.53).We established the susceptibility baseline of RSB to tetraniliprole(lethal concentration at LC_(50)=0.727 mg/L)and investigated the resistance level of 6 field populations to tetraniliprole.All tested strains that had resistance to chlorantraniliprole exhibited moderate-to high-level resistance to tetraniliprole(resistance ratio=27.7-806.8).Detection of ryanodine receptor(RyR)mutations showed that the Y4667C,Y4667D,I4758M,and Y4891F mutations were present in tested RSB field populations.RyR mutations were responsible for the cross-resistance between tetraniliprole and chlorantraniliprole.Further,the clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated protein 9-mediated genome-modified flies were used to study the contribution of RyR mutations to tetraniliprole resistance.The order of contribution of a single RyR mutation to tetraniliprole resistance was Y4667D>G4915E>Y4667C~~I4758M>Y4891F.In addition,the I4758M and Y4667C double mutations conferred higher tetraniliprole resistance than single Y4667C mutations.These results can guide resistance management practices for diamides in RSB and other arthropods.展开更多
文摘Previous studies have documented the occurrence of glyphosate-resistant （GR） goosegrass （Eleusine indica （L.） Gaertn.） and, in at least some cases, resistance is due to an altered target site. Research was performed to determine if an altered target site was responsible for GR in a Tennessee, United States goosegrass population （TennGR）. DNA sequencing revealed a mutation in TennGR plants conferring the Prol06Ser 5-enolpyruvylshikimate-3-phosphate synthase （EPSPS） substitution previously identified in other GR populations. F2 populations were derived from TennGR plants crossed with plants from a glyphosate-susceptible population （TennGS） and analyzed for their response to glyphosate and genotyped at the EPSPS locus. Plants from the F2 populations segregated 1：2：1 sensitive：intermediate：resistant in response to a selec- tive dose of glyphosate, and these responses co-segregated with the EPSPS genotypes （PP106, PS106, and SS106）. To separately investigate the effect of the Prol06Ser substitution on GR, glyphosate dose-response curves and 50% effective dose （EDso） values were compared among the three genotypes and the two parental populations. The SS106 genotype was 3.4-fold resistant relative to the PP106 genotype, identical to the resistance level obtained when comparing the resistant and susceptible parental populations. We conclude that the mutation conferring a Prol06Ser EPSPS mutation is solely responsible for GR in the TennGR goosegrass population.
基金Project supported by the National Natural Science Foundation of China (Nos. 90916009 and11172336)
文摘Through introducing the analytical problem of the plate with convection into the solution of the transient heat conduction thermal stress field model of the elastic plate, the stress reduction factor is presented explicitly in its dimensionless form. A new stress reduction factor is introduced for the purpose of comparison. The proper- ties and appropriate conditions of the stress reduction factor, the first and second ther- mal shock resistance （TSR） parameters for the high and low Biot numbers, respectively, and the approximation formulas for the intermediate Blot number-interval are discussed. To investigate the TSR of ceramics more accurately, it is recommended to combine the heat transfer theory with the theory of thermoelasticity or fracture mechanics or use a numerical method. The critical rupture temperature difference and the critical rup- ture dimensionless time can be used to characterize the TSR of ceramics intuitively and legibly.
基金Project supported by the National Natural Science Foundation of China(Nos.11472066 and11172336)the Chongqing Natural Science Foundation(No.cstc2013jcyj A50018)+1 种基金the Program for New Century Excellent Talents in University(No.ncet-13-0634)the Fundamental Research Funds for the Central Universities(Nos.CDJZR13240021 and CDJZR14328801)
文摘The effects of mechanical boundary conditions, often encountered in thermalstructural engineering, on the thermal shock resistance（TSR） of ultra-high temperature ceramics（UHTCs） are studied by investigating the TSR of a UHTC plate with various types of constraints under the first, second, and third type of thermal boundary conditions. The TSR of UHTCs is strongly dependent on the heat transfer modes and severity of the thermal environments. Constraining the displacement of the lower surface in the thickness direction can significantly decrease the TSR of the UHTC plate, which is subject to the thermal shock at the upper surface. In contrast, the TSR of the UHTC plate with simply supported edges or clamped edges around the lower surface is much better.
基金funded by the National Natural Science Foundation of China to SFW(32272576)the National Key Research and Developmental Program of China(2022YFD1400900).
文摘The rice stem borer(RSB),Chilo suppressalis,a notorious rice pest in China,has evolved a high resistance level to commonly used insecticides.Tetraniliprole,a new anthranilic diamide insecticide,effectively controls multiple pests,including RSB.However,the potential resistance risk of RSB to tetraniliprole is still unknown.In this study,the tetraniliprole-selection(Tet-R)strain was obtained through 10 continuous generations of selection with tetraniliprole 30%lethal concentration(LC_(30)).The realized heritability(h^(2))of the Tet-R strain was 0.387,indicating that resistance of RSB to tetraniliprole developed rapidly under the continuous selection of tetraniliprole.The Tet-R strain had a high fitness cost(relative fitness=0.53).We established the susceptibility baseline of RSB to tetraniliprole(lethal concentration at LC_(50)=0.727 mg/L)and investigated the resistance level of 6 field populations to tetraniliprole.All tested strains that had resistance to chlorantraniliprole exhibited moderate-to high-level resistance to tetraniliprole(resistance ratio=27.7-806.8).Detection of ryanodine receptor(RyR)mutations showed that the Y4667C,Y4667D,I4758M,and Y4891F mutations were present in tested RSB field populations.RyR mutations were responsible for the cross-resistance between tetraniliprole and chlorantraniliprole.Further,the clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated protein 9-mediated genome-modified flies were used to study the contribution of RyR mutations to tetraniliprole resistance.The order of contribution of a single RyR mutation to tetraniliprole resistance was Y4667D>G4915E>Y4667C~~I4758M>Y4891F.In addition,the I4758M and Y4667C double mutations conferred higher tetraniliprole resistance than single Y4667C mutations.These results can guide resistance management practices for diamides in RSB and other arthropods.
