Cry toxins produced by Bacillus thuringiensis （Bt） are effective biological insecticides against certain insect species. However, there are potential risks of the evolved resistance of insects to Cry toxin owing to ...Cry toxins produced by Bacillus thuringiensis （Bt） are effective biological insecticides against certain insect species. However, there are potential risks of the evolved resistance of insects to Cry toxin owing to decreased binding of toxins to target sites in the brush border membranes of the larva midgut. The Cry toxins with different binding sites in the larval midgut have been considered to be a good combination to deploy in delaying resistance evolution. Bioassay results demonstrated that the toxicity of different Cry toxins ranked differently for each species. The toxicity ranking was CrylAc〉CrylAb〉Cry2Ab for Helicoverpa armigera, CrylB〉CrylC〉Cry2Ab for Spodoptera exigua, and Cry2Ab〉CrylB〉 CrylC for S. litura. Only Cry2Ab was toxic to Agrotis ipsilon. Binding experiments were performed with ^125I-CrylAb, ^125I-CrylAc, ^125I-CrylB, ^125I-CrylC, ^125I-Cry2Ab and the brush border membranes vesicles （BBMV） from H. armigera, S. exigua, S. litura and A. ipsilon. The binding of CrylAb and CrylAc was shown to be saturable by incubating with increasing concentrations of H. armigera BBMV （Kd=（45.00＋2.01） nmol L-1 and （12.80＋0.18） nmol L^-1, respectively; Bmax=（54.95±l.79） ng and （55.44±0.91） ng, separately）. The binding of CrylB was shown to be saturable by incubating with increasing concentrations ofS. exigua BBMV （Kd=（23.26±1.66） nmol L^-1; Bmax=（65.37±1.87） ng）. The binding of ^125I-Cry toxins was shown to be non-saturable by incubating with increasing concentrations of S. litura and A. ipsilon BBMV. In contrast, CrylB and CrylC showed some combination with the BBMV orS. litura, and a certain amount of Cry2Ab could bind to the BBMV ofA. ipsilon. These observations suggest that a future strategy could be devised for the focused combination of specific cry genes in transgenic crops to control target pests, widen the spectrum of insecticide effectiveness and postpone insect resistance evolution.展开更多
Hemipteran group of sap sucking insect pests cause worldwide crop destruction. The role of mannose specific monocot lectins have recently been worked out in hemipteran pest management. The present article demonstrates...Hemipteran group of sap sucking insect pests cause worldwide crop destruction. The role of mannose specific monocot lectins have recently been worked out in hemipteran pest management. The present article demonstrates the insecticidal efficacy of a new mannose specific agglutinin, isolated from tubers of Amorphophallus paeonifolius (AMTL) against a wide range of hemipteran insects. The 25 kDa dimeric protein was found to inhibit the survivability of hemipteran insects namely, Lipaphis erysimi, Aphis gossypii and Dysdercus cingulatus quite efficiently, as analysed by synthetic diet based bioassay experiments. Surface Plasmon Resonance study detected binding of insecticidal AMTL to insect gut brush border membrane vesicle (BBMV) protein, an absolute prerequisite for conferring toxicity against target insects. Further ligand blot analysis spotted a ~74 kDa glycoprotein as putative receptor of AMTL from the total BBMV protein fraction of Lipaphis erysimi. Phylogenetic analysis showed a significant relatedness of AMTL to the previously established monocot lectin Galanthus nivalis agglutinin (GNA) in terms of their conserved mannose binding domains, agglutinating ability of rabbit erythrocytes and insecticidal efficacies. These information project AMTL as a promising candidate in preventing crop loss caused due to hemipteran insect attack.展开更多
Brown planthopper, the sap sucking hemipteran pest, is one of the major contributors to the yield loss of rice through the world. To combat the situation researchers are interested identifying genes from plant origin ...Brown planthopper, the sap sucking hemipteran pest, is one of the major contributors to the yield loss of rice through the world. To combat the situation researchers are interested identifying genes from plant origin having potentiality to develop hemipteran pest resistance. Interestingly, it was observed that rice plants expressing ASAL, a monocot mannose binding lectin, showed significant resistance to brown planthopper and green leafhopper. Additionally, antibiotic resistant marker gene free ASAL expressing rice lines were developed to overcome the biosafety issues. However, the basis behind the resistance against planthoppers is still not clearly understood. Ligand blot assay was performed with total BBMV protein from BPH and a ~56 kDa receptor protein was detected. LC MS/MS analysis revealed that the receptor protein is NADH quinone oxidoreductase (NQO), a key player in electron transport chain, insect defense response and male/female gametogenesis. Presumably interaction of ASAL with NQO may lead to toxicity and loss of fecundity among BPH feeding on ASAL expressing transgenic rice plants. These findings provide a stable scientific basis for considering these transgenic ASAL expressing rice plants as significant product for combating BPH attack associated yield loss of rice.展开更多
基金supported by the Nationa l973 Program of China (2012CB114104)the National Natural Science Foundation of China (31071694, 31171858)the International Joint Project between China and UK of National Natural Science Foundation of China and RoyalSociety (31111130203)
文摘Cry toxins produced by Bacillus thuringiensis （Bt） are effective biological insecticides against certain insect species. However, there are potential risks of the evolved resistance of insects to Cry toxin owing to decreased binding of toxins to target sites in the brush border membranes of the larva midgut. The Cry toxins with different binding sites in the larval midgut have been considered to be a good combination to deploy in delaying resistance evolution. Bioassay results demonstrated that the toxicity of different Cry toxins ranked differently for each species. The toxicity ranking was CrylAc〉CrylAb〉Cry2Ab for Helicoverpa armigera, CrylB〉CrylC〉Cry2Ab for Spodoptera exigua, and Cry2Ab〉CrylB〉 CrylC for S. litura. Only Cry2Ab was toxic to Agrotis ipsilon. Binding experiments were performed with ^125I-CrylAb, ^125I-CrylAc, ^125I-CrylB, ^125I-CrylC, ^125I-Cry2Ab and the brush border membranes vesicles （BBMV） from H. armigera, S. exigua, S. litura and A. ipsilon. The binding of CrylAb and CrylAc was shown to be saturable by incubating with increasing concentrations of H. armigera BBMV （Kd=（45.00＋2.01） nmol L-1 and （12.80＋0.18） nmol L^-1, respectively; Bmax=（54.95±l.79） ng and （55.44±0.91） ng, separately）. The binding of CrylB was shown to be saturable by incubating with increasing concentrations ofS. exigua BBMV （Kd=（23.26±1.66） nmol L^-1; Bmax=（65.37±1.87） ng）. The binding of ^125I-Cry toxins was shown to be non-saturable by incubating with increasing concentrations of S. litura and A. ipsilon BBMV. In contrast, CrylB and CrylC showed some combination with the BBMV orS. litura, and a certain amount of Cry2Ab could bind to the BBMV ofA. ipsilon. These observations suggest that a future strategy could be devised for the focused combination of specific cry genes in transgenic crops to control target pests, widen the spectrum of insecticide effectiveness and postpone insect resistance evolution.
文摘Hemipteran group of sap sucking insect pests cause worldwide crop destruction. The role of mannose specific monocot lectins have recently been worked out in hemipteran pest management. The present article demonstrates the insecticidal efficacy of a new mannose specific agglutinin, isolated from tubers of Amorphophallus paeonifolius (AMTL) against a wide range of hemipteran insects. The 25 kDa dimeric protein was found to inhibit the survivability of hemipteran insects namely, Lipaphis erysimi, Aphis gossypii and Dysdercus cingulatus quite efficiently, as analysed by synthetic diet based bioassay experiments. Surface Plasmon Resonance study detected binding of insecticidal AMTL to insect gut brush border membrane vesicle (BBMV) protein, an absolute prerequisite for conferring toxicity against target insects. Further ligand blot analysis spotted a ~74 kDa glycoprotein as putative receptor of AMTL from the total BBMV protein fraction of Lipaphis erysimi. Phylogenetic analysis showed a significant relatedness of AMTL to the previously established monocot lectin Galanthus nivalis agglutinin (GNA) in terms of their conserved mannose binding domains, agglutinating ability of rabbit erythrocytes and insecticidal efficacies. These information project AMTL as a promising candidate in preventing crop loss caused due to hemipteran insect attack.
文摘Brown planthopper, the sap sucking hemipteran pest, is one of the major contributors to the yield loss of rice through the world. To combat the situation researchers are interested identifying genes from plant origin having potentiality to develop hemipteran pest resistance. Interestingly, it was observed that rice plants expressing ASAL, a monocot mannose binding lectin, showed significant resistance to brown planthopper and green leafhopper. Additionally, antibiotic resistant marker gene free ASAL expressing rice lines were developed to overcome the biosafety issues. However, the basis behind the resistance against planthoppers is still not clearly understood. Ligand blot assay was performed with total BBMV protein from BPH and a ~56 kDa receptor protein was detected. LC MS/MS analysis revealed that the receptor protein is NADH quinone oxidoreductase (NQO), a key player in electron transport chain, insect defense response and male/female gametogenesis. Presumably interaction of ASAL with NQO may lead to toxicity and loss of fecundity among BPH feeding on ASAL expressing transgenic rice plants. These findings provide a stable scientific basis for considering these transgenic ASAL expressing rice plants as significant product for combating BPH attack associated yield loss of rice.
