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Zhaojun Han - One of the best experts on this subject based on the ideXlab platform.
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novel alternative splicing of gaba receptor rdl exon 9 from Laodelphax striatellus modulates agonist potency
Insect Science, 2020Co-Authors: Jie Jiang, Qiutang Huang, Lixin Huang, Feng Chen, Zhaojun Han, Chengwang Sheng, Chunqing ZhaoAbstract:The resistance to dieldrin gene (RDL) encodes the primary subunit of the insect ionotropic γ-aminobutyric acid (GABA) receptor (GABAR), which is the target of phenylpyrazole and isoxazoline insecticides. The splice variants in exons 3 and 6 of RDL, which have been widely explored in many insects, modulate the agonist potency of the homomeric RDL GABAR and potentially play an important role in the development of insects. In the present study, four splice variants of exon 9 were identified in RDL of the small brown planthopper, Laodelphax striatellus (LsRDL), resulting in LsRDL-9a, LsRDL-9a', LsRDL-9b, and LsRDL-9c. LsRDL-9a has one more amino acid (E, glutamic acid) compared with LsRDL-9a', and LsRDL-9b lacked two amino acids and had seven different amino acids compared with LsRDL-9c. Two-electrode voltage-clamp recording on LsRDLs expressed in Xenopus oocytes showed that alternative splicing of exon 9 has significant impact on LsRDL sensitivity to the agonists GABA and β-alanine, whereas no significant difference was observed in the potencies of the non-competitive antagonists (NCAs) ethiprole and fluralaner on the splice variants. Our results suggest that alternative splicing of RDL exon 9 broadens functional capabilities of the GABAR in L. striatellus by influencing the action of GABA.
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fiprole insecticide resistance of Laodelphax striatellus electrophysiological and molecular docking characterization of a2 n rdl gaba receptors
Pest Management Science, 2018Co-Authors: Chengwang Sheng, Feng Chen, Zhaojun Han, John E Casida, Kathleen A Durkin, Chunqing ZhaoAbstract:Background Phenylpyrazole (fiprole) insecticides, including ethiprole, fipronil and flufiprole with excellent activity on rice planthoppers, are very important in Asia but resistance has developed after decades of use. The molecular mechanism of fipronil- but not ethiprole-resistance has been previously studied in rice planthoppers. In our laboratory, a small brown planthopper Laodelphax striatellus strain with ethiprole-resistance was cultured and the molecular mechanisms of ethiprole resistance and of cross-resistance among fiprole insecticides were investigated. Results Ethiprole-resistant L. striatellus has >5000-fold resistance compared to the susceptible strain, and exhibits around 200-fold cross-resistance with fipronil and flufiprole. RDL genes were isolated from susceptible and ethiprole-resistant L. striatellus and expressed in Xenopus oocytes. Electrophysiological studies showed fiprole insecticides inhibited γ-aminobutyric acid (GABA)-induced current with IC50 = 0.1-1.4 μM to LsRDL-S homomers. In LsRDL-R with A2'N mutation, only 1-13% inhibition was observed on treatment with 10 μM ethiprole, fipronil or flufiprole. Homology models indicate A2'N mutation allows crosslinking hydrogen bonding between Asn sidechains at the 2' position around the channel pore, blocking insecticides from interacting near this position. In contrast, insecticides showed favorable binding near A2' in wild-type L. striatellus. Conclusion Cross-resistance is increasing for fiprole insecticides in L. striatellus and management strategies are necessary to minimize resistance. © 2018 Society of Chemical Industry.
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deltamethrin is metabolized by cyp6fu1 a cytochrome p450 associated with pyrethroid resistance in Laodelphax striatellus
Pest Management Science, 2018Co-Authors: Mohammed Esmail Abdalla Elzaki, Mohammad Asaduzzaman Miah, Haomiao Zhang, Ling Jiang, Yingchuan Peng, Zhaojun HanAbstract:Background Cytochrome P450s (CYPs) are known to play a major role in metabolizing a wide range compounds. CYP6FU1 has been found to be over-expressed in a deltamethrin-resistant strain of Laodelphax striatellus. This study was conducted to express CYP6FU1 in Sf9 cells as a recombinant protein, to confirm its ability to degrade deltamethrin, chlorpyrifos, imidacloprid and traditional P450 probing substrates. Results Carbon monoxide difference spectrum analysis indicated that the intact CYP6FU1 protein was expressed in insect Sf9 cells. Catalytic activity tests with four traditional P450 probing substrates revealed that the expressed CYP6FU1 preferentially metabolized p-nitroanisole and ethoxyresorufin, but not ethoxycoumarin and luciferin-HEGE. The enzyme kinetic parameters were tested using p-nitroanisole. The michaelis constant (Km ) and catalytic constant (Kcat ) values were 17.51 ± 4.29 µm and 0.218 ± 0.001 pmol min-1 mg-1 protein, respectively. Furthermore, CYP6FU1 activity for degradation of insecticides was tested by measuring substrate depletion and metabolite formation. The chromatogram analysis showed obvious nicotinamide-adenine dinucleotide phosphate (NADPH)-dependent depletion of deltamethrin, and formation of the unknown metabolite. Mass spectra and the molecular docking model showed that the metabolite was 4-hydroxy-deltamethrin. However, the recombinant CYP6FU1 could not metabolize imidacloprid and chlorpyrifos. Conclusion These results confirmed that the over-expressed CYP6FU1 contributes to deltamethrin resistance in L. striatellus, and p-nitroanisole might be a potential diagnostic probe for deltamethrin metabolic resistance detection and monitoring. © 2017 Society of Chemical Industry.
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imidacloprid is degraded by cyp353d1v2 a cytochrome p450 overexpressed in a resistant strain of Laodelphax striatellus
Pest Management Science, 2017Co-Authors: Mohammed Esmail Abdalla Elzaki, Mohammad Asaduzzaman Miah, Haomiao Zhang, Ling Jiang, Zhaojun HanAbstract:BACKGROUND Cytochrome P450s are associated with the metabolising of a wide range of compounds, including insecticides. CYP353D1v2 has been found to be overexpressed in an imidacloprid-resistant strain of Laodelphax striatellus. Thus, this study was conducted to express CYP353D1v2 in Sf9 cells as a recombinant protein, to assess its ability to metabolise imidacloprid. RESULTS Western blot and carbon monoxide difference spectrum analysis indicated that the intact CYP353D1v2 protein had been successfully expressed in Sf9 insect cells. Catalytic activity tests with four traditional P450-activity-probing substrates found that the expressed CYP353D1v2 preferentially metabolised p-nitroanisole, ethoxycoumarin and ethoxyresorufin with specific activities of 32.70, 0.317 and 1.22 pmol min−1 pmol−1 protein respectively, but no activity to luciferin-H EGE. The enzyme activity for degrading imidacloprid was tested by measuring substrate depletion and formation of the metabolite. Kinetic parameters for imidacloprid were Km 5.99 ± 0.95 µm and kcat 0.03 ± 0.0004 min−1. The chromatogram analysis showed clearly the NADPH-dependent depletion of imidacloprid and the formation of an unknown metabolite. The UPLC-MS mass spectrum demonstrated that the metabolite was an oxidative product of imidacloprid, 5-hydroxy-imidacloprid. CONCLUSION These results suggest that CYP353D1v2 in L. striatellus is capable of degrading imidacloprid, and that enzyme activity can be evaluated well only by some traditional probing substrates. © 2017 Society of Chemical Industry
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Imidacloprid is hydroxylated by Laodelphax striatellus CYP6AY3v2.
Insect molecular biology, 2017Co-Authors: Ran Wang, Yu-xi Zhu, L. Deng, H. Zhang, Q. Wang, M. Yin, P. Song, Mohammed Esmail Abdalla Elzaki, Zhaojun HanAbstract:Laodelphax striatellus (Fallen) is one of the most destructive pests of rice, and has developed high resistance to imidacloprid. Our previous work indicated a strong association between imidacloprid resistance and the overexpression of a cytochrome P450 gene CYP6AY3v2 in a L. striatellus imidacloprid resistant strain (Imid-R). In this study, a transgenic Drosophila melanogaster line that overexpressed the L. striatellus CYP6AY3v2 gene was established and was found to confer increased levels of imidacloprid resistance. Furthermore, CYP6AY3v2 was co-expressed with D. melanogaster cytochrome P450 reductase (CPR) in Spodoptera frugiperda 9 (SF9) cells. A carbon monoxide difference spectra analysis indicated that CYP6AY3v2 was expressed predominately in its cytochrome P450 (P450) form, which is indicative of a good-quality functional enzyme. The recombinant CYP6AY3v2 protein efficiently catalysed the model substrate P-nitroanisole to p-nitrophenol with a maximum velocity (Vmax) of 60.78 ± 3.93 optical density (mOD)/min/mg protein. In addition, imidacloprid itself was metabolized by the recombinant CYP6AY3v2/nicotinamide adenine dinucleotide 2'-phosphate reduced tetrasodium salt (NADPH) CPR microsomes in in vitro assays (catalytic constant (Kcat) = 0.34 pmol/min/pmol P450, michaelis constant (Km) = 41.98 μM), and imidacloprid depletion and metabolite peak formation were with a time dependence. The data provided direct evidence that CYP6AY3v2 is capable of hydroxylation of imidacloprid and conferring metabolic resistance in L. striatellus.
Xiao-yue Hong - One of the best experts on this subject based on the ideXlab platform.
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recent infection by wolbachia alters microbial communities in wild Laodelphax striatellus populations
Microbiome, 2020Co-Authors: Xingzhi Duan, Yan Guo, Jingtao Sun, Yu-xi Zhu, Ary A Hoffmann, Xiao-li Bing, Linting Wang, Xiaohan Shu, Matsukura Keiichiro, Xiao-yue HongAbstract:Host-associated microbial communities play an important role in the fitness of insect hosts. However, the factors shaping microbial communities in wild populations, including genetic background, ecological factors, and interactions among microbial species, remain largely unknown. Here, we surveyed microbial communities of the small brown planthopper (SBPH, Laodelphax striatellus) across 17 geographical populations in China and Japan by using 16S rRNA amplicon sequencing. Using structural equation models (SEM) and Mantel analyses, we show that variation in microbial community structure is likely associated with longitude, annual mean precipitation (Bio12), and mitochondrial DNA variation. However, a Wolbachia infection, which is spreading to northern populations of SBPH, seems to have a relatively greater role than abiotic factors in shaping microbial community structure, leading to sharp decreases in bacterial taxon diversity and abundance in host-associated microbial communities. Comparative RNA-Seq analyses between Wolbachia-infected and -uninfected strains indicate that the Wolbachia do not seem to alter the immune reaction of SBPH, although Wolbachia affected expression of metabolism genes. Together, our results identify potential factors and interactions among different microbial species in the microbial communities of SBPH, which can have effects on insect physiology, ecology, and evolution.
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genomic analysis of wolbachia from Laodelphax striatellus delphacidae hemiptera reveals insights into its jekyll and hyde mode of infection pattern
Genome Biology and Evolution, 2020Co-Authors: Xiao-li Bing, Dian-shu Zhao, Jingtao Sun, Kaijun Zhang, Xiao-yue HongAbstract:Wolbachia is a widely distributed intracellular bacterial endosymbiont among invertebrates. The wStriCN, the Wolbachia strain that naturally infects an agricultural pest Laodelphax striatellus, has a "Jekyll and Hyde" mode of infection pattern with positive and negative effects: It not only kills many offspring by inducing cytoplasmic incompatibility (CI) but also significantly increases host fecundity. In this study, we assembled the draft genome of wStriCN and compared it with other Wolbachia genomes to look for clues to its Jekyll and Hyde characteristics. The assembled wStriCN draft genome is 1.79 Mb in size, which is the largest Wolbachia genome in supergroup B. Phylogenomic analysis showed that wStriCN is closest to Wolbachia from Asian citrus psyllid Diaphorina citri. These strains formed a monophylogentic clade within supergroup B. Compared with other Wolbachia genomes, wStriCN contains the most diverse insertion sequence families, the largest amount of prophage sequences, and the most ankyrin domain protein coding genes. The wStriCN genome encodes components of multiple secretion systems, including Types I, II, IV, VI, Sec, and Tac. We detected three pairs of homologs for CI factors CifA and CifB. These proteins harbor the catalytic domains responsible for CI phenotypes but are phylogenetically and structurally distinct from all known Cif proteins. The genome retains pathways for synthesizing biotin and riboflavin, which may explain the beneficial roles of wStriCN in its host planthoppers, which feed on nutrient-poor plant sap. Altogether, the genomic sequencing of wStriCN provides insight into understanding the phylogeny and biology of Wolbachia.
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salivary dnase ii from Laodelphax striatellus acts as an effector that suppresses plant defence
New Phytologist, 2019Co-Authors: Hai-jian Huang, Jiarong Cui, Xue Xia, Jie Chen, Chuanxi Zhang, Xiao-yue HongAbstract:Extracellular DNA, released by damaged plant cells, acts as a damage-associated molecular pattern (DAMP). We demonstrated previously that the small brown planthopper (Laodelphax striatellus, SBPH) secreted DNase II when feeding on artificial diets. However, the function of DNase II in insect feeding remained elusive. The influences of DNase II on SBPHs and rice plants were investigated by suppressing expression of DNase II or by application of heterogeneously expressed DNase II. We demonstrated that DNase II is mainly expressed in the salivary gland and is responsible for DNA-degrading activity of saliva. Knocking down the expression of DNase II resulted in decreased performance of SBPH reared on rice plants. The dsDNase II-treated SBPH did not influenced jasmonic acid (JA), salicylic acid (SA), ethylene (ET) pathways, but elicited a higher level of H2 O2 and callose accumulation. Application of heterogeneously expressed DNase II in DNase II-deficient saliva slightly reduced the wound-induced defence response. We propose a DNase II-based invading model for SBPH feeding on host plants, and provide a potential target for pest management.
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Antibiotic exposure perturbs the bacterial community in the small brown planthopper Laodelphax striatellus.
Insect Science, 2019Co-Authors: Xu Zhang, Hai-jian Huang, Tong-pu Li, Chun-ying Zhou, Dian-shu Zhao, Xiao-li Bing, Xiao-yue HongAbstract:: Bacteria symbionts in herbivores play an important role in host biology and ecology, and are affected by environmental factors such as temperature, diet, habitat, antibiotics and so on. However, the effects of antibiotics on the microbiome of the small brown planthopper Laodelphax striatellus (SBPH) remain unclear. Here, we studied the effects of tetracycline on the diversity and composition of bacterial colonies in different tissues of SBPH using high throughput sequencing of 16S ribosomal RNA amplicons. Our results show that Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria were most abundant in SBPH, and the genera Asaia and Wolbachia were most abundant in all body parts of SBPH. Antibiotic treatment had persistent effects on the composition of the SBPH microbiome. Tetracycline depleted the population of Firmicutes, Bacteroidetes, Tenericutes and Fusobacteria, and nearly 100% eliminated Wolbachia, Bacteroides and Abiotrophia in SBPH. Together, these results suggest that antibiotic exposure affects the bacteria symbionts of different body parts in SBPH and will facilitate future studies of the bacterial symbionts of arthropod hosts.
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Wolbachia localization during Laodelphax striatellus embryogenesis.
Journal of Insect Physiology, 2019Co-Authors: Yan Guo, Jun-tao Gong, Hai-jian Huang, Xiao-yue HongAbstract:Abstract Wolbachia are intracellular bacteria carried by thousands of arthropod species. The success of Wolbachia is due to efficient vertical transmission by the host maternal germline. Wolbachia’s behavior during host oogenesis is well characterized, although their behavior during embryogenesis is unclear. Vertical transmission of Wolbachia wStri in the small brown planthopper, Laodelphax striatellus is extraordinarily efficient. To understand why, we investigated its localization and dynamics in L. striatellus embryos. Microscopic observations indicated that the Wolbachia were mainly localized at the anterior region of the embryo during early embryogenesis. The distribution of Wolbachia within the anterior region was established during oogenesis, and according to a phylogenetic analysis, may be due to intrinsic factors in Wolbachia. We observed that wStri migrated to the posterior part cells during late embryogenesis, in the region where gonads were formed. An expression profile of Wolbachia-infected host embryonic development genes revealed Ddx1 mRNAs, which is required for host viability and in the germ line, accumulated in the posterior region of 3-day-old embryos, while other development genes mRNAs were significantly more abundant in the posterior region of 6-day-old embryos. These genes thus appear to be associated with the localization of Wolbachia wStri in the anterior region, although their functions remain unclear. These results can explain Wolbachia wStri high prevalence in L. striatellus.
Jichao Fang - One of the best experts on this subject based on the ideXlab platform.
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a salivary calcium binding protein from Laodelphax striatellus acts as an effector that suppresses defense in rice
Pest Management Science, 2021Co-Authors: Jichao Fang, Tian Tian, Lu Wang, Hao Zhang, Shiying YangAbstract:Background Calcium (Ca2+ )-binding proteins in the saliva of herbivorous insects function as effectors to attenuate host plant defenses and thus improve insect feeding performance. Silencing these genes via transgenic plant-mediated RNAi is thus a promising pest control strategy. However, their sequences and functions in the small brown planthopper Laodelphax striatellus (SBPH) remain to be investigated. Results We identified a putative EF-hand Ca2+ -binding protein (LsECP1) in SBPH watery saliva. LsECP1 was expressed extremely high in the salivary glands but at a low level during the egg stage. Transient LsECP1 expression in rice cells indicated its cytoplasm and nucleus localization. The bacterially expressed recombinant LsECP1 protein exhibited Ca2+ -binding activity. Rice plants fed by SBPH nymphs with knocked down LsECP1 exhibited higher levels of cytosolic Ca2+ , jasmonic acid (JA), jasmonoyl-isoleucine (JA-Ile), and H2 O2 ; Consistently, application of heterogeneously expressed LsECP1 protein suppressed wound-induced JA, JA-Ile, and H2 O2 accumulation in rice. Thus, LsECP1 knockdown by dsRNA injection resulted in reduced feeding, fecundity, and survival rates of SBPH reared on rice plants. Transgenic rice plants constitutively expressing LsECP1 dsRNA were produced, and plant-mediated LsECP1 knockdown enhanced rice resistance to SBPH. Conclusion SBPH LsECP1 acts as an effector to impair host rice defense responses and promotes SBPH performance. This discovery provides a potential gene target for plant-mediated RNAi-based pest management. This article is protected by copyright. All rights reserved.
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induced expression of small heat shock proteins is associated with thermotolerance in female Laodelphax striatellus planthoppers
Cell Stress & Chaperones, 2019Co-Authors: Lihua Wang, Yueliang Zhang, Ary A Hoffmann, Lei Pan, Qin Wang, Yangchun Han, Hongtao Niu, Dan Shan, Jichao FangAbstract:Insects are often exposed to high temperature stress in natural environments, but the mechanisms involved in thermotolerance in many insect groups like Hemiptera are not well known. To explore possible mechanisms of thermotolerance in the hemipteran pest Laodelphax striatellus, which damages rice through direct feeding and viral transmission, small heat shock proteins (sHsps) implicated in thermotolerance in other insect groups were identified. The seven sHsps identified have a conserved alpha crystallin domain, a variable N-terminal region, and shared relative low identities to each other. Three of the sHsp genes (LsHsp20.5, LsHsp21.5, and LsHsp21.6) exhibited higher basal expression than the other four genes but showed weak or no heat-induced expression. The other four genes (LsHsp20.1, LsHsp21.2, LsHsp21.4, and LsHsp22.0) were induced up to 3306-fold by heat. Injection of dsRNA indicated that expression of these sHsps was associated with thermotolerance, and Escherichia coli transformed with LsHsp21.2 and LsHsp20.1 showed relatively higher thermotolerance. These results point to an important functional role of these sHsps for thermotolerance in L. striatellus.
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resistance monitoring and cross resistance role of cyp6cw1 between buprofezin and pymetrozine in field populations of Laodelphax striatellus fallen
Scientific Reports, 2017Co-Authors: Yueliang Zhang, Huifang Guo, Zewen Liu, Qiong Yang, Lihua Wang, Yangchun Han, Baosheng Liu, Jichao FangAbstract:Monitoring resistance and investigating insecticide resistance mechanisms are necessary for controlling the small brown planthopper, Laodelphax striatellus. The susceptibility to four common insecticides of L. striatellus collected from Jiangsu, Anhui, Zhejiang and Jilin provinces of China in 2015 was monitored. The results showed that all field populations remained susceptible to chlorpyrifos and thiamethoxam with resistance ratios (RRs) of 2.3- to 9.5 and 1.6- to 3.3, respectively, while the insects had developed moderate pymetrozine resistance with RRs of 18.7 to 34.5. Resistance against buprofezin had developed to an alarmingly high level in three southeastern provinces of China with RRs of 108.8 to 156.1, but in Jilin it had an RR of only 26.6. Moreover, in line with both the buprofezin and pymetrozine resistance levels, we found LsCYP6CW1 to be over-expressed in all field L. striatellus populations, which indicated that it might be important for cross-resistance between buprofezin and pymetrozine. RNA interference (RNAi) ingestion resulted in the effective suppression of LsCYP6CW1 expression, and significantly increased susceptibility to both buprofezin and pymetrozine compared with the control, which further confirmed that overexpression of LsCYP6CW1 was involved in the cross-resistance to buprofezin and pymetrozine in field L. striatellus populations.
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overexpression of carboxylesterase 1 and mutation f439h of acetylcholinesterase 1 are associated with chlorpyrifos resistance in Laodelphax striatellus
Pesticide Biochemistry and Physiology, 2013Co-Authors: Yueliang Zhang, Huifang Guo, Lihua Wang, Jichao FangAbstract:Previous studies investigating a chlorpyrifos-resistant (YN-CPF) strain indicated chlorpyrifos resistance was a result of Laodelphax striatellus carboxylesterase-1 (Ls.CarE1)-mediated detoxification and acetylcholinesterase (AChE) insensitivity. In this study, we found via immunoblotting that the protein level of Ls.CarE1 was significantly overexpressed in the YN-CPF strain compared with that observed in the chlorpyrifos-susceptible (YN) strain. Moreover, the full-length gene encoding acetylcholinesterase-1, designated Ls.AChE1, was cloned from the YN-CPF and YN strains. A sequence analysis found an amino acid mutation (Phe439His) in Ls.AChE1 (corresponding to F331 in the standard matured AChE sequence of Torpedo californica) and the mutation frequencies of Phe439His were 91%, 54% and 0% in the YN-CPF, the chlorpyrifos relaxed selection (YN-RSF) and the YN strains, respectively. The results offer new evidence that support the involvement of both AChE insensitivity and CarE metabolism in the resistance to chlorpyrifos in the YN-CPF strain.
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overexpression of a p450 gene cyp6cw1 in buprofezin resistant Laodelphax striatellus fallen
Pesticide Biochemistry and Physiology, 2012Co-Authors: Yueliang Zhang, Gufeng Zhang, Huifang Guo, Qiong Yang, Lihua Wang, Jichao FangAbstract:Cytochrome P450 monooxygenase (P450)-mediated detoxification is an important mechanism involved in the resistance to neurotoxic pesticides. However, the molecular basis of the mechanism of P450s, as associated with the resistance to growth regulator insecticides (IGRs) remains largely unknown. In this study, a resistance strain (YN-BPF) of Laodelphax striatellus was developed, with 59.9-fold resistance to buprofezin, through 42 generations of discontinuous selections of the susceptible strain (YN) with buprofezin (an IGR). A synergistic study in vivo and a biochemical study in vitro indicated that an enhanced detoxification mediated by P450s to some extent contributes to the buprofezin resistance in the YN-BPF strain. A total of 38 cDNA sequences encoding tentative unique P450 genes were identified in an L. striatellus transcriptome database, and the mRNA expression level of these genes was examined in the YN and YN-BPF strains using quantitative real-time PCR (qPCR). A single P450 gene, CYP6CW1, was highly overexpressed (22.78-fold) in the YN-BPF strain compared with the YN strain. Based on the analysis of insects with similar genetic backgrounds, our results provided evidence for the role of CYP6CW1 in the resistance of L. striatellus to buprofezin.
Xifeng Wang - One of the best experts on this subject based on the ideXlab platform.
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ribavirin targets sugar transporter 6 to suppress acquisition and transmission of rice stripe tenuivirus by its vector Laodelphax striatellus
Pest Management Science, 2020Co-Authors: Jamaluddin Hajano, Lu Zhang, Wenwen Liu, Ahmed Raza, Xifeng WangAbstract:BACKGROUND Rice stripe tenuivirus (RSV) is one of the most destructive pathogens of rice and other cereal crops. The virus is transmitted by the small brown planthopper (SBPH, Laodelphax striatellus) in a circulative-propagative manner. Thus, blocking transmission by the insect vector would provide an effective strategy to prevent epidemic outbreaks of the disease. RESULTS In this study, we explored the effect of ribavirin on acquisition and transmission of the virus by specifically inhibiting the expression of sugar transporter 6 (LsSt-6), which was recently reported as a key vector component for RSV transmission. Ribavirin at the highest concentration tested (250 μmol L-1 ) significantly reduced RSV acquisition and transmission efficiency by SBPHs through inhibiting LsSt-6 messenger RNA (mRNA) level. Survival of the model insect Spodoptera frugiperda cell line (Sf9) was 95.0 ± 2.2 and 85.6 ± 2.1% after exposure to 250 μmol L-1 ribavirin or 8-azaguanine, respectively. Further study confirmed that 250 μmol L-1 ribavirin also significantly reduced LsSt-6 mRNA and protein levels in Sf9 cells. However, 8-azaguanine did not significantly inhibit viral infectivity and LsSt-6 mRNA levels in SBPH or the Sf9 cell line. CONCLUSION This result provides evidence that ribavirin has the potential to disrupt LsSt-6 expression but not others like viral RNAs to prevent acquiring RSV, which leads to less viral accumulation in SBPH tissues and thereby lower transmission efficiency. © 2020 Society of Chemical Industry.
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complete genome sequence and characterization of a new iflavirus from the small brown planthopper Laodelphax striatellus
Virus Research, 2019Co-Authors: Peipei Zhang, Wenwen Liu, Mengji Cao, Sebastien Massart, Xifeng WangAbstract:Abstract A novel iflavirus, tentatively named Laodelphax striatellus iflavirus 1 (LsIV1), was identified in Laodelphax striatellus by total RNA-sequencing, and its genome sequence was confirmed by Sanger sequencing. The complete genome consisted of 10,831 nucleotides with a polyA tail and included one open reading frame, encoding a 361.7-kD polyprotein. Conserved motifs for structural proteins, helicase, protease, and RNA-dependent RNA polymerase were identified by aligning the deduced amino acid sequence of LsIV1 with several other iflaviruses. The genome has the highest identity with another planthopper iflavirus, nilaparvata lugens honeydew virus-3 (39.7%), under the species demarcation threshold (90%). Results of the identities and phylogenetic analysis based on the deduced amino acid sequences of the complete polyprotein and helicase of LsIV1 and other iflaviruses, indicated it is a new species belonging to the family Iflaviridae. Furthermore, we did not observe any differences of biological characterizations like development and reproduction between viruliferous and virus-free SBPH. Meanwhile, we found that female could transmit LsIV1 with higher transmission efficiency.
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Differential proteomics profiling of the ova between healthy and Rice stripe virus-infected female insects of Laodelphax striatellus
Scientific reports, 2016Co-Authors: Beibei Liu, Faliang Qin, Wenwen Liu, Xifeng WangAbstract:Rice stripe virus-infected females of the small brown planthopper (SBPH, Laodelphax striatellus) usually lay fewer eggs with a longer hatch period, low hatchability, malformation and retarded or defective development compared with healthy females. To explore the molecular mechanism of those phenomena, we analyzed the differential proteomics profiling of the ova between viruliferous and healthy female insects using an isobaric tag for relative and absolute quantitation (iTRAQ) approach. We obtained 147 differentially accumulated proteins: 98 (66.7%) proteins increased, but 49 (33.3%) decreased in the ova of the viruliferous females. RT-qPCR was used to verify the 12 differential expressed proteins from iTRAQ, finding that trends in the transcriptional change for the 12 genes were consistent with those at the proteomic level. Differentially expressed proteins that were associated with meiosis (serine/threonine-protein phosphatase 2B and cyclin B3) and mitosis (cyclin B3 and dynein heavy chain) in viruliferous ova may contribute to low hatchability and defective or retarded development. Alterations in the abundance of proteins involved in the respiratory chain and nutrition metabolism may affect embryonic development. Our study begins to explain macroscopical developmental phenomena and explore the mechanisms by which Rice stripe virus impacts the development of SBPH.
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Five Proteins of Laodelphax striatellus Are Potentially Involved in the Interactions between Rice Stripe Virus and Vector
2013Co-Authors: Ruyi Xiong, Xifeng Wang, Yijun ZhouAbstract:Rice stripe virus (RSV) is the type member of the genus Tenuivirus, which relies on the small brown planthopper (Laodelphax striatellus Fallén) for its transmission in a persistent, circulative-propagative manner. To be transmitted, virus must cross the midgut and salivary glands epithelial barriers in a transcytosis mechanism where vector receptors interact with virions, and as propagative virus, RSV need utilize host components to complete viral propagation in vector cells. At present, these mechanisms remain unknown. In this paper, we screened L. striatellus proteins, separated by two-dimensional electrophoresis (2-DE), as potential RSV binding molecules using a virus overlay assay of protein blots. The results, five L. striatellus proteins that bound to purified RSV particles in vitro were resolved and identified using mass spectrometry. The virus-binding capacities of five proteins were further elucidated in yeast two-hybrid screen (YTHS) and virus-binding experiments of expressed proteins. Among five proteins, the receptor for activated protein kinase C (RACK) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH3) did not interact with RSV nucleocapsid protein (NCP) in YTHS and in far-Western blot, and three ribosomal proteins (RPL5, RPL7a and RPL8) had specific interactions with RSV. In dot immunobinding assay (DIBA), all five proteins were able to bind to RSV particles. The five proteins ’ potential contributions to the interactions between RSV and L. striatellus were discussed. We proposed that RACK and GAPDH3 might be involved in the epithelial transcytosis of virus particles, and three ribosomal proteins probably played potential crucial roles in th
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five proteins of Laodelphax striatellus are potentially involved in the interactions between rice stripe virus and vector
PLOS ONE, 2011Co-Authors: Ruyi Xiong, Xifeng Wang, Yijun ZhouAbstract:Rice stripe virus (RSV) is the type member of the genus Tenuivirus, which relies on the small brown planthopper (Laodelphax striatellus Fallen) for its transmission in a persistent, circulative-propagative manner. To be transmitted, virus must cross the midgut and salivary glands epithelial barriers in a transcytosis mechanism where vector receptors interact with virions, and as propagative virus, RSV need utilize host components to complete viral propagation in vector cells. At present, these mechanisms remain unknown. In this paper, we screened L. striatellus proteins, separated by two-dimensional electrophoresis (2-DE), as potential RSV binding molecules using a virus overlay assay of protein blots. The results, five L. striatellus proteins that bound to purified RSV particles in vitro were resolved and identified using mass spectrometry. The virus-binding capacities of five proteins were further elucidated in yeast two-hybrid screen (YTHS) and virus-binding experiments of expressed proteins. Among five proteins, the receptor for activated protein kinase C (RACK) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH3) did not interact with RSV nucleocapsid protein (NCP) in YTHS and in far-Western blot, and three ribosomal proteins (RPL5, RPL7a and RPL8) had specific interactions with RSV. In dot immunobinding assay (DIBA), all five proteins were able to bind to RSV particles. The five proteins' potential contributions to the interactions between RSV and L. striatellus were discussed. We proposed that RACK and GAPDH3 might be involved in the epithelial transcytosis of virus particles, and three ribosomal proteins probably played potential crucial roles in the infection and propagation of RSV in vector cells.
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molecular characterization and expression pattern of three gaba receptor like subunits in the small brown planthopper Laodelphax striatellus hemiptera delphacidae
Pesticide Biochemistry and Physiology, 2017Co-Authors: Qi Wei, Cong Fen GaoAbstract:Ionotropic γ-aminobutyric acid (GABA)-gated chloride channel receptors mediate rapid inhibitory neurotransmission in vertebrates and invertebrates. GABA receptors are well known to be the molecular targets of synthetic insecticides or parasiticides. Three GABA receptor-like subunits, LsLCCH3, LsGRD and LS8916, of the small brown planthopper, Laodelphax striatellus (Fallen), a major insect pest of crop systems in East Asia, had been identified and characterized in this study. All three genes were cloned using the reverse transcriptase polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). They shared common structural features with known Cys-loop ligand-gated ion channels (LGICs): the well-conserved dicysteine-loop structures, an extracellular N-terminal domain containing six distinct regions (loops A–F) that form the ligand binding sites and four transmembrane regions (TM1–4). Additionally, temporal and spatial transcriptional profiling analysis indicated that Lslcch3 was significantly higher than the other two genes. All of them were expressed at higher levels in fifth-instar nymph and adults than in eggs and from first- to fourth-instar nymph. They were predominantly expressed in the heads of 2-d old female adults. These findings enhanced our understanding of cys-loop LGIC functional characterization in Hemiptera and provided a useful basis for the development of improved insecticides that targeting this important agricultural pest.
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expression pattern and pharmacological characterisation of two novel alternative splice variants of the glutamate gated chloride channel in the small brown planthopper Laodelphax striatellus
Pest Management Science, 2017Co-Authors: Yaoxue Dong, Qi Wei, Li-xiang Wang, Cong Fen GaoAbstract:BACKGROUND Glutamate-gated chloride channels (GluCl) mediate fast inhibitory neurotransmission in invertebrate nervous systems. Although only one GluCl gene was presented in insects, it showed diverse alternative splicing that was speculated could affect channel function and pharmacology. RESULTS In this study, we isolated GluCl cDNAs from adults of the small brown planthopper (SBPH) Laodelphax striatellus and showed that six L. striatellus GluCl variants (LsGluCl-AS, LsGluCl-BS, LsGluCl-CS, LsGluCl-AL, LsGluCl-BL, LsGluCl-CL) were present in the SBPH. The expression patterns of six variants differed among developmental stages (egg, first- to fifth-instar nymphs, male and female adults) and among the body parts (head, thorax, abdomen, leg) of the female adult SBPH. All the transcripts were abundant in the head of the adult. When expressed in African clawed frog, Xenopus laevis, oocytes, the two functional variants (LsGluCl-AS, LsGluCl-AL) had similar EC50 and IC50 values for L-glutamate and channel blockers picrotoxinin and fipronil. CONCLUSION This study represents a comprehensive molecular, expression and pharmacological characterisation of GluCl in the SBPH. These findings should be useful in providing more opportunities to discover novel insect control chemicals. © 2016 Society of Chemical Industry
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Resistance monitoring and cross-resistance patterns of three rice planthoppers, Nilaparvata lugens, Sogatella furcifera and Laodelphax striatellus to dinotefuran in China
Pesticide biochemistry and physiology, 2016Co-Authors: Wei Zhang, Kai Zhang, Li-xiang Wang, Shuai Zhang, Cong Fen GaoAbstract:Three rice planthoppers, brown planthopper, Nilaparvata lugens, white-backed planthopper, Sogatella furcifera and small brown planthopper, Laodelphax striatellus, are important pests of cultivated rice in tropical and temperate Asia. They have caused severe economic loss and developed resistance to insecticides from most chemical classes. Dinotefuran is the third neonicotinoid which possesses a broad spectrum and systemic insecticidal activity. We determined the susceptibility of dinotefuran to field populations from major rice production areas in China from 2013 to 2015. All the populations of S. furcifera and L. striatellus were kept susceptible to dinotefuran (0.7 to 1.4-fold of S. furcifera and 1.1-to 3.4-fold of L. striatellus) However, most strains of N. lugens (except FQ15) collected in 2015 had developed moderate resistance to dinotefuran, with resistance ratios (RR) ranging from 23.1 to 100.0 folds. Cross-resistance studies showed that chlorpyrifos-resistant and buprofezin-resistant Sogatella furcifera, chlorpyrifos-resistant and fipronil-resistant L. striatellus, imidacloprid-resistant and buprofezin-resistant Nilaparvata lugens exhibited negligible or no cross-resistance to dinotefuran. Synergism tests showed that piperonyl butoxide (PBO) produced a high synergism of dinotefuran effects in the DY15 and JS15 populations (2.14 and 2.52-fold, respectively). The obvious increase in resistance to dinotefuran in N. lugens indicates that insecticide resistance management strategies are urgently needed to prevent or delay further increase of insecticide resistance in N. lugens.
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knockdown of the ionotropic γ aminobutyric acid receptor gabar rdl gene decreases fipronil susceptibility of the small brown planthopper Laodelphax striatellus hemiptera delphacidae
Archives of Insect Biochemistry and Physiology, 2015Co-Authors: Qi Wei, Chundong Niu, Yaoxue Dong, Cong Fen GaoAbstract:Insect γ-aminobutyric acid receptors (GABARs) are important molecular targets of cyclodiene and phenylpyrazole insecticides. Previously GABARs encoding rdl (resistant to dieldrin) genes responsible for dieldrin and fipronil resistance were identified in various economically important insect pests. In this study, we cloned the open reading frame cDNA sequence of rdl gene from fipronil-susceptible and fipronil-resistant strains of Laodelphax striatellus (Lsrdl). Sequence analysis confirmed the presence of a previously identified resistance-conferring mutation. Different alternative splicing variants of Lsrdl were noted. Injection of dsLsrdl reduced the mRNA abundance of Lsrdl by 27-82%, and greatly decreased fipronil-induced mortality of individuals from both susceptible and resistant strains. These data indicate that Lsrdl encodes a functional RDL subunit that mediates susceptibility to fipronil. Additionally, temporal and spatial expression analysis showed that Lsrdl was expressed at higher levels in eggs, fifth-instar nymphs, and female adults than in third-instar and fourth-instar nymphs. Lsrdl was predominantly expressed in the heads of 2-day-old female adults. All these results provide useful background knowledge for better understanding of fipronil resistance related ionotropic GABA receptor rdl gene expressed variants and potential functional differences in insects.
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susceptibility of sogatella furcifera and Laodelphax striatellus hemiptera delphacidae to six insecticides in china
Journal of Economic Entomology, 2014Co-Authors: Kai Zhang, Wei Zhang, Shuai Zhang, Lanfeng Ban, Cong Fen GaoAbstract:The whitebacked planthopper, Sogatella furcifera (Horvath), and small brown planthopper, Laodelphax striatellus (Fallen), both are important crop pests throughout China, especially in rice. Application of chemical insecticides is the major control practice. Consequently, insecticide resistance has become an urgent issue. In this study, resistance levels to six conventional insecticides were evaluated for these two species collected from major occurring areas of China. Additionally, imidacloprid- (resistance ratio [RR] = 10.4-fold) and buprofezin (RR = 15.1-fold)-resistant strains of whitebacked planthopper were obtained through laboratory selections for cross-resistance profiling and synergism assessment to understand resistance mechanisms. The results showed that all tested populations of both species exhibited low to high levels of resistance to chlorpyrifos, while remaining susceptible to thiamethoxam. Three of the 14 whitebacked planthopper populations showed low to moderate resistance to imidacloprid, while all small brown planthopper populations reminded susceptible. All small brown planthopper and whitebacked planthopper (except one) populations showed at least moderate resistance (RR = 10.1-271.1) to buprofezin. All small brown planthopper populations remained susceptible to pymetrozine and nitenpyram, and all whitebacked planthopper populations remained susceptible to isoprocarb. The imidacloprid-resistant whitebacked planthopper strain showed no significant cross-resistance to other tested insecticides. However, the buprofezin-resistant strain exhibited a low-level cross-resistance (CR = 3.1) to imidacloprid. Piperonyl butoxide, triphenyl phosphate, and diethylmaleate displayed no synergism effect on the resistant whitebacked planthopper strains.
