Southern corn leaf blight(SCLB)caused by Cochliobolus heterostrophus,is a widespread foliar disease that has a substantial impact on maize yield in the Huang-Huai-Hai Region of China.Pydiflumetofen(Pyd),a new succinat...Southern corn leaf blight(SCLB)caused by Cochliobolus heterostrophus,is a widespread foliar disease that has a substantial impact on maize yield in the Huang-Huai-Hai Region of China.Pydiflumetofen(Pyd),a new succinate dehydrogenase inhibitor(SDHI),has been found as a promising fungicide for the efficient control of SCLB,however,resistance of C.heterostrophus to Pyd has not been studied well.Here,five Pyd-resistant mutants were generated through fungicide adaptation.Sequence alignment analysis revealed that these mutants primarily mutated in ChSdhB and ChSdhD,with three genotypes:ChSdhB^(H277Y),ChSdhB^(I279T)and ChSdhD^(H133Y),exhibiting two distinct categories of resistance:high resistance(HR)and moderate resistance(MR),among which the resistance factors were 214.22 and 44.33-53.67,respectively.These mutants were more pathogenic than the wild-type parental strains,but there was a significant reduction in mycelial growth rate and sporulation in the resistant mutants,indicating a significant fitness cost associated with resistance to Pyd.In addition,this study revealed a positive cross-resistance between Pyd and another SDHI fungicide cyclobutrifluram.However,no cross-resistance was found between Pyd and other classes of fungicides,including prochloraz,fludioxonil,iprodione or pyraclostrobin.Homology modeling and molecular docking further confirmed that point mutations of ChSdhB^(H277Y),ChSdhB^(I279T),and ChSdhD^(H133Y)could reduce binding affinity between Pyd and its target subunits from-74.07,-74.07,-152.52 kcal mol^(-1)to-3.90,-4.95,-9.93 kcal mol^(-1),respectively.These findings not only provided valuable insights for managing SCLB caused by C.heterostrophus,but also enhanced our understanding of molecular mechanism underlying plant pathogen resistance to Pyd.展开更多
Biological methodologies (</span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"> and </span><i><span ...Biological methodologies (</span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">in vivo</span></i><span style="font-family:Verdana;">) were tested on </span><i><span style="font-family:Verdana;">Venturia inaequalis</span></i><span style="font-family:Verdana;"> to assay sensitivity of populations treated with the SDHI penthiopyrad, fluxapyroxad and fluopyram that showed a field poor control in an experimental Centre. In comparison, sensible populations were tested. </span><i><span style="font-family:Verdana;">I</span></i><i><span style="font-family:Verdana;">n vitro</span></i><span style="font-family:Verdana;"> trials, the poorly controlled populations presented moderate increases of EC</span><sub><span style="font-family:Verdana;">50</span></sub><span style="font-family:Verdana;"> and RF values in all three years in which tests were carried out. The </span><i><span style="font-family:Verdana;">in vivo</span></i><span style="font-family:Verdana;"> trials in glasshouse showed that the activity of SDHI fungicides on field poorly controlled populations was highly reduced. These populations can be defined as “resistant” as the high loss of sensitivity and activity were repeatedly assessed in field and glasshouse. Trials showed that these reductions were manifested by curative applications and not by preventive ones, as already ascertained for </span><i><span style="font-family:Verdana;">V. inaequalis </span></i><span style="font-family:Verdana;">populations resistant to AP and DMI fungicides. </span><span><span style="font-family:Verdana;">The cross-resistance of resistant populations to the three SDHIs was highly positive among them. In bibliography, there are only researches of cross-resistance among SDHIs starting from isolates resistant to boscalid, with results of different sensitivities and cross-resistance. These results with populations of </span><i><span style="font-family:Verdana;">V. inaequalis</span></i><span style="font-family:Verdana;"> resistant to the three SDHI offer practical evaluations in cross-resistance.展开更多
Fusarium fujikuroi,the causal agent of rice bakanae disease(RBD),contains five succinate dehydrogenase(Sdh)subunits:FfSdhA,FfSdhB,FfSdhC1,FfSdhC2,and FfSdhD.However,the role of these subunits in regulating sensitivity...Fusarium fujikuroi,the causal agent of rice bakanae disease(RBD),contains five succinate dehydrogenase(Sdh)subunits:FfSdhA,FfSdhB,FfSdhC1,FfSdhC2,and FfSdhD.However,the role of these subunits in regulating sensitivity to succinate dehydrogenase inhibitors(SDHIs)is largely unknown.Here,we conducted targeted gene disruption and phenotypic assays for all Sdh subunits and found that the deletion mutants of FfSdhA,FfSdhB,and FfSdhD exhibited severe defects in hyphal growth,conidiation,virulence,and sensitivity to CaCl_(2) and oxidative stresses.To a lesser extent,the mycelial growth rate and conidial production ofΔFfSdhC1 were also decreased as compared to those of the wild-type strain JS16.In addition,fungicide sensitivity assays showed that deletion of FfSdhA,B,C1,or D led to decreased sensitivity to all SDHIs tested.Unexpectedly,we were unable to obtain a FfSdhC1+C2 double mutant and further found significant up-regulation of FfSdhC2 inΔFfSdhC1,indicating that FfSdhC1 and-C2 might be essential for fungal growth although the FfSdhC2 deletion mutant was indistinguishable from the wild-type strain.These findings provide useful information for enhancing our understanding of the biological functions of the Sdh subunits in pathogenic fungi.展开更多
基金supported by the National Key Research and Development Program of China(2023YFD1401504)the Open Project of Anhui Province Key Laboratory of Pesticide Resistance Management on Grain and Vegetable Pests,China(PKLPRMGVP202402)+3 种基金the Programs for the Scientific Research Activities of Academic and Technical Leaders of Anhui Province,China(2020D251)the Development Fund for Talent Personnel of Anhui Agricultural University,China(rc342006)the University Synergy Innovation Program of Anhui Province,China(GXXT-2021-059)Anhui Province Agricultural Eco-Environmental Protection and Quality Safety Industry Technology System,China。
文摘Southern corn leaf blight(SCLB)caused by Cochliobolus heterostrophus,is a widespread foliar disease that has a substantial impact on maize yield in the Huang-Huai-Hai Region of China.Pydiflumetofen(Pyd),a new succinate dehydrogenase inhibitor(SDHI),has been found as a promising fungicide for the efficient control of SCLB,however,resistance of C.heterostrophus to Pyd has not been studied well.Here,five Pyd-resistant mutants were generated through fungicide adaptation.Sequence alignment analysis revealed that these mutants primarily mutated in ChSdhB and ChSdhD,with three genotypes:ChSdhB^(H277Y),ChSdhB^(I279T)and ChSdhD^(H133Y),exhibiting two distinct categories of resistance:high resistance(HR)and moderate resistance(MR),among which the resistance factors were 214.22 and 44.33-53.67,respectively.These mutants were more pathogenic than the wild-type parental strains,but there was a significant reduction in mycelial growth rate and sporulation in the resistant mutants,indicating a significant fitness cost associated with resistance to Pyd.In addition,this study revealed a positive cross-resistance between Pyd and another SDHI fungicide cyclobutrifluram.However,no cross-resistance was found between Pyd and other classes of fungicides,including prochloraz,fludioxonil,iprodione or pyraclostrobin.Homology modeling and molecular docking further confirmed that point mutations of ChSdhB^(H277Y),ChSdhB^(I279T),and ChSdhD^(H133Y)could reduce binding affinity between Pyd and its target subunits from-74.07,-74.07,-152.52 kcal mol^(-1)to-3.90,-4.95,-9.93 kcal mol^(-1),respectively.These findings not only provided valuable insights for managing SCLB caused by C.heterostrophus,but also enhanced our understanding of molecular mechanism underlying plant pathogen resistance to Pyd.
文摘Biological methodologies (</span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">in vivo</span></i><span style="font-family:Verdana;">) were tested on </span><i><span style="font-family:Verdana;">Venturia inaequalis</span></i><span style="font-family:Verdana;"> to assay sensitivity of populations treated with the SDHI penthiopyrad, fluxapyroxad and fluopyram that showed a field poor control in an experimental Centre. In comparison, sensible populations were tested. </span><i><span style="font-family:Verdana;">I</span></i><i><span style="font-family:Verdana;">n vitro</span></i><span style="font-family:Verdana;"> trials, the poorly controlled populations presented moderate increases of EC</span><sub><span style="font-family:Verdana;">50</span></sub><span style="font-family:Verdana;"> and RF values in all three years in which tests were carried out. The </span><i><span style="font-family:Verdana;">in vivo</span></i><span style="font-family:Verdana;"> trials in glasshouse showed that the activity of SDHI fungicides on field poorly controlled populations was highly reduced. These populations can be defined as “resistant” as the high loss of sensitivity and activity were repeatedly assessed in field and glasshouse. Trials showed that these reductions were manifested by curative applications and not by preventive ones, as already ascertained for </span><i><span style="font-family:Verdana;">V. inaequalis </span></i><span style="font-family:Verdana;">populations resistant to AP and DMI fungicides. </span><span><span style="font-family:Verdana;">The cross-resistance of resistant populations to the three SDHIs was highly positive among them. In bibliography, there are only researches of cross-resistance among SDHIs starting from isolates resistant to boscalid, with results of different sensitivities and cross-resistance. These results with populations of </span><i><span style="font-family:Verdana;">V. inaequalis</span></i><span style="font-family:Verdana;"> resistant to the three SDHI offer practical evaluations in cross-resistance.
基金supported by the Key Project of National Natural Science Foundation of China(U21A20219)National Key Research and Development Program of China(2022YFD1400100)China Agriculture Research System(CARS-03-29).
文摘Fusarium fujikuroi,the causal agent of rice bakanae disease(RBD),contains five succinate dehydrogenase(Sdh)subunits:FfSdhA,FfSdhB,FfSdhC1,FfSdhC2,and FfSdhD.However,the role of these subunits in regulating sensitivity to succinate dehydrogenase inhibitors(SDHIs)is largely unknown.Here,we conducted targeted gene disruption and phenotypic assays for all Sdh subunits and found that the deletion mutants of FfSdhA,FfSdhB,and FfSdhD exhibited severe defects in hyphal growth,conidiation,virulence,and sensitivity to CaCl_(2) and oxidative stresses.To a lesser extent,the mycelial growth rate and conidial production ofΔFfSdhC1 were also decreased as compared to those of the wild-type strain JS16.In addition,fungicide sensitivity assays showed that deletion of FfSdhA,B,C1,or D led to decreased sensitivity to all SDHIs tested.Unexpectedly,we were unable to obtain a FfSdhC1+C2 double mutant and further found significant up-regulation of FfSdhC2 inΔFfSdhC1,indicating that FfSdhC1 and-C2 might be essential for fungal growth although the FfSdhC2 deletion mutant was indistinguishable from the wild-type strain.These findings provide useful information for enhancing our understanding of the biological functions of the Sdh subunits in pathogenic fungi.
