Diaphorina citri is a global citrus pest.As a vector insect,it can transmit the causative agents of citrus huanglongbing,causing irreversible losses to the citrus industry.The acquisition of genomic information can pr...Diaphorina citri is a global citrus pest.As a vector insect,it can transmit the causative agents of citrus huanglongbing,causing irreversible losses to the citrus industry.The acquisition of genomic information can provide a molecular genetic basis for effective control of D.citri.Here,the DNBSEQ™,Oxford Nanopore Technologies,and Hi-C technologies are applied to generate a high-quality chromosome-level genome of D.citri.The genome size of D.citri was 523.78 Mb with a scaffold N50 of 47.05 Mb distributed on 13 chromosomes.A total of 250.64 Mb(47.85%)repeat sequences and 24048 protein-coding genes were predicted.Genome resequencing of female and male individuals indicated that the sex chromosome system of D.citri is XO.Phylogenetic analysis demonstrated that D.citri and Pachypsylla venusta,which separated from their most recent common ancestor about 336.62 million years ago,were the most closely related.Additionally,we identified genes potentially involved in detoxification metabolism,pathogen transmission,and honeydew secretion for further investigation.The high-quality genome provides an important reference for developing effective management strategies of D.citri.展开更多
Huanglongbing(HLB) is a devastating disease that has led to an acute crisis for growers of citrus, one of the world's most important fruit crops. The phloem-feeding Asian citrus psyllid(ACP), Diaphorina citri, is ...Huanglongbing(HLB) is a devastating disease that has led to an acute crisis for growers of citrus, one of the world's most important fruit crops. The phloem-feeding Asian citrus psyllid(ACP), Diaphorina citri, is the main pest at the new shoot stage and is the only natural vector of HLB pathogenic bacteria. Little is known about how plants perceive and defend themselves from this destructive pest. Here, we characterized changes in the expression of various genes in citrus plants that were continuously infested by D. citri for different durations(12, 24, and 48 h). A total of 5 219 differentially expressed genes(DEGs) and 643 common DEGs were identified across all time points. Several pathways related to defense were activated, such as peroxisome, alpha-linolenic acid metabolism, and phenylpropanoid and terpenoid biosynthesis, and some pathways related to growth and signal transduction were suppressed in response to D. citri infestation. The expression of genes including kinases(CML44, CIPK6, and XTH6), phytohormones(SAMT, LOX6, and NPR3), transcription factors(bHLH162, WRKY70, and WRKY40), and secondary metabolite synthesis-related genes(PAL, 4CL2, UGT74B1 and CYP82G1) was significantly altered in response to D. citri infestation. The findings of this study greatly enhance our understanding of the mechanisms underlying the defense response of citrus plants to D. citri infestation at the molecular level. Functional characterization of the candidate defense-related genes identified in this study will aid the molecular breeding of insect-resistant citrus varieties.展开更多
The Asian citrus psyllid (ACP) Diaphorina citri Kuwayama vectors pathogens that cause huanglongbing (HLB) or citrus greening devastating and economically im- portant disease present in most citrus growing regions....The Asian citrus psyllid (ACP) Diaphorina citri Kuwayama vectors pathogens that cause huanglongbing (HLB) or citrus greening devastating and economically im- portant disease present in most citrus growing regions. Young citrus shoots are required for psyllid reproduction and development. During winter citrus trees produce little or no new growth. Overwintering adults reproduce in spring on newly emerging shoots also attractive to other pests and beneficial insects. Botanicals and relatively selective insecti- cides could help to conserve beneficial insects and reduce pest resistance to insecticides. Sprays of Azadirachtin (Neem), Tropane (Datura), Spirotetramat, Spinetoram, and broad- spectrum Imidacloprid were evaluated to control ACP in spring and summer on 10-year-old "Kinow" Citrus reticulata Blanco trees producing new growth. Psyllid populations were high averaging 5-9 nymphs or adults per sample before treatment application. Nymphs or adults were significantly reduced to 0.5-1.5 per sample in all treatments for 3 weeks, aver- age 61%-83% reduction. No significant reduction in ladybeetles Adalia bipunctata, Ane- glei scardoni, Cheilomenes sexmaculata, and Coccinella septempunctata was observed. Syrphids, spiders and green lacewings were reduced in treated trees except with Tropane. Studies are warranted to assess impact of these predators on ACP and interaction with insecticides. Observed reduction in ACP populations may not be enough considering its reproductive potential and role in the spread of HLB. Follow-up sprays may be required to achieve additional suppression using rotations of different insecticides.展开更多
Bacillus thuringiensis(Bt)toxins are effective in controlling insect pests either through the spraying of products or when expressed in transgenic crops.The discovery of endophytic Bt strains opened new perspectives f...Bacillus thuringiensis(Bt)toxins are effective in controlling insect pests either through the spraying of products or when expressed in transgenic crops.The discovery of endophytic Bt strains opened new perspectives for studies aimed at the control of sap‐sucking insects,such as the Asian citrus psyllid Diaphorina citri Kuwayama(Hemiptera:Liviidae),a vector of“Candidatus Liberibacter spp.,”associated with citrus huanglongbing(HLB).In this study,translocation of endophytic Bt strains in citrus seedlings inoculated with Bt suspension delivered by soil‐drench,and their systemic pathogenicity to D.citri nymphs were investigated.The pathogenicity of three wild‐type Bt strains against D.citri third‐instar nymphs was demonstrated.Among the 10 recombinant strains tested(each of them harboring a single cry or cyt gene),3 can be highlighted,causing 42%–77%and 66%–90%nymphal mortality at 2 and 5 d after inoculation,respectively.The isolation of Bt cells from young citrus shoots and dead nymphs,and PCR performed with specific primers,confirmed the involvement of the Bt strains in the psyllid mortality.This is the first report showing the translocation of Bt strains from citrus seedling roots to shoots and their potential to control D.citri nymphs that fed on these soil‐drench inoculated seedlings.The Bt strains that caused the highest mortality rates have the potential to be used as bioinsecticides to control D.citri and the identified genes can be used for the production of transgenic Bt citrus.展开更多
文摘Diaphorina citri is a global citrus pest.As a vector insect,it can transmit the causative agents of citrus huanglongbing,causing irreversible losses to the citrus industry.The acquisition of genomic information can provide a molecular genetic basis for effective control of D.citri.Here,the DNBSEQ™,Oxford Nanopore Technologies,and Hi-C technologies are applied to generate a high-quality chromosome-level genome of D.citri.The genome size of D.citri was 523.78 Mb with a scaffold N50 of 47.05 Mb distributed on 13 chromosomes.A total of 250.64 Mb(47.85%)repeat sequences and 24048 protein-coding genes were predicted.Genome resequencing of female and male individuals indicated that the sex chromosome system of D.citri is XO.Phylogenetic analysis demonstrated that D.citri and Pachypsylla venusta,which separated from their most recent common ancestor about 336.62 million years ago,were the most closely related.Additionally,we identified genes potentially involved in detoxification metabolism,pathogen transmission,and honeydew secretion for further investigation.The high-quality genome provides an important reference for developing effective management strategies of D.citri.
基金supported by Key Realm R&D Program of Guangdong Province (Grant No. 2020B0202090005)Special Fund for Scientific Innovation Strategy-construction of High Level Academy of Agriculture Science (Grant No. R2020PY-JG002)the President Foundation of Guangdong Academy of Agricultural Sciences (Grant No. 202030)。
文摘Huanglongbing(HLB) is a devastating disease that has led to an acute crisis for growers of citrus, one of the world's most important fruit crops. The phloem-feeding Asian citrus psyllid(ACP), Diaphorina citri, is the main pest at the new shoot stage and is the only natural vector of HLB pathogenic bacteria. Little is known about how plants perceive and defend themselves from this destructive pest. Here, we characterized changes in the expression of various genes in citrus plants that were continuously infested by D. citri for different durations(12, 24, and 48 h). A total of 5 219 differentially expressed genes(DEGs) and 643 common DEGs were identified across all time points. Several pathways related to defense were activated, such as peroxisome, alpha-linolenic acid metabolism, and phenylpropanoid and terpenoid biosynthesis, and some pathways related to growth and signal transduction were suppressed in response to D. citri infestation. The expression of genes including kinases(CML44, CIPK6, and XTH6), phytohormones(SAMT, LOX6, and NPR3), transcription factors(bHLH162, WRKY70, and WRKY40), and secondary metabolite synthesis-related genes(PAL, 4CL2, UGT74B1 and CYP82G1) was significantly altered in response to D. citri infestation. The findings of this study greatly enhance our understanding of the mechanisms underlying the defense response of citrus plants to D. citri infestation at the molecular level. Functional characterization of the candidate defense-related genes identified in this study will aid the molecular breeding of insect-resistant citrus varieties.
文摘The Asian citrus psyllid (ACP) Diaphorina citri Kuwayama vectors pathogens that cause huanglongbing (HLB) or citrus greening devastating and economically im- portant disease present in most citrus growing regions. Young citrus shoots are required for psyllid reproduction and development. During winter citrus trees produce little or no new growth. Overwintering adults reproduce in spring on newly emerging shoots also attractive to other pests and beneficial insects. Botanicals and relatively selective insecti- cides could help to conserve beneficial insects and reduce pest resistance to insecticides. Sprays of Azadirachtin (Neem), Tropane (Datura), Spirotetramat, Spinetoram, and broad- spectrum Imidacloprid were evaluated to control ACP in spring and summer on 10-year-old "Kinow" Citrus reticulata Blanco trees producing new growth. Psyllid populations were high averaging 5-9 nymphs or adults per sample before treatment application. Nymphs or adults were significantly reduced to 0.5-1.5 per sample in all treatments for 3 weeks, aver- age 61%-83% reduction. No significant reduction in ladybeetles Adalia bipunctata, Ane- glei scardoni, Cheilomenes sexmaculata, and Coccinella septempunctata was observed. Syrphids, spiders and green lacewings were reduced in treated trees except with Tropane. Studies are warranted to assess impact of these predators on ACP and interaction with insecticides. Observed reduction in ACP populations may not be enough considering its reproductive potential and role in the spread of HLB. Follow-up sprays may be required to achieve additional suppression using rotations of different insecticides.
基金This study was financed in part by the Coordenacao de Aperfeigoamento de Pessoal de Nivel Superior-Brasil(CAPES)and by the Brazilian Agricultural Research Corporation(EMBRAPA-grant number 03.13.03.006.00.00)。
文摘Bacillus thuringiensis(Bt)toxins are effective in controlling insect pests either through the spraying of products or when expressed in transgenic crops.The discovery of endophytic Bt strains opened new perspectives for studies aimed at the control of sap‐sucking insects,such as the Asian citrus psyllid Diaphorina citri Kuwayama(Hemiptera:Liviidae),a vector of“Candidatus Liberibacter spp.,”associated with citrus huanglongbing(HLB).In this study,translocation of endophytic Bt strains in citrus seedlings inoculated with Bt suspension delivered by soil‐drench,and their systemic pathogenicity to D.citri nymphs were investigated.The pathogenicity of three wild‐type Bt strains against D.citri third‐instar nymphs was demonstrated.Among the 10 recombinant strains tested(each of them harboring a single cry or cyt gene),3 can be highlighted,causing 42%–77%and 66%–90%nymphal mortality at 2 and 5 d after inoculation,respectively.The isolation of Bt cells from young citrus shoots and dead nymphs,and PCR performed with specific primers,confirmed the involvement of the Bt strains in the psyllid mortality.This is the first report showing the translocation of Bt strains from citrus seedling roots to shoots and their potential to control D.citri nymphs that fed on these soil‐drench inoculated seedlings.The Bt strains that caused the highest mortality rates have the potential to be used as bioinsecticides to control D.citri and the identified genes can be used for the production of transgenic Bt citrus.