Cuticular hydrocarbons form a barrier that protects terrestrial insects from water loss via the epicuticle.Lipophorin loads and transports lipids,including hydrocarbons,from one tissue to another.In some insects,the l...Cuticular hydrocarbons form a barrier that protects terrestrial insects from water loss via the epicuticle.Lipophorin loads and transports lipids,including hydrocarbons,from one tissue to another.In some insects,the lipophorin receptor(LpR),which binds to lipophorin and accepts its lipid cargo,is essential for female fecundity because it mediates the incorporation of lipophorin by developing oocytes.However,it is unclear whether LpR is involved in the accumulation of cuticular hydrocarbons and its precise role in aphid reproduction remains unknown.We herein present the results of our molecular characterization,phylogenetic analysis,and functional annotation of the pea aphid(Acyrthosiphon pisum)LpR gene(ApLpR).This gene was transcribed throughout the A.pisum life cycle,but especially during the embryonic stage and in the abdominal cuticle.Furthermore,we optimized the RHA interference(RNAi)parameters by determining the ideal dose and duration for gene silencing in the pea aphid.We observed that the RNAi-based ApLpR suppression significantly decreased the internal and cuticular hydrocarbon contents as well as adult fecundity.Additionally,a deficiency in cuticular hydrocarbons increased the susceptibility of aphids to desiccation stress,with decreased survival rates under simulated drought conditions.Moreover,ApLpR expression levels significantly increased in response to the desiccation treatment.These results confirm that ApLpR is involved in transporting hydrocarbons and protecting aphids from desiccation stress.Furthermore,this gene is vital for aphid reproduction.Therefore,the ApLpR gene of A.pisum may be a novel RNAi target relevant for insect pest management.展开更多
Phenoloxidases(POs)are required for the pea aphid s defense against bacterial and fungal infection.Prophenoloxidases(PPOs)are protcolytically converted to its active form PO through a clip domain serine protease casca...Phenoloxidases(POs)are required for the pea aphid s defense against bacterial and fungal infection.Prophenoloxidases(PPOs)are protcolytically converted to its active form PO through a clip domain serine protease cascade.In this study,we identified five clip domain serine proteases in the pea aphids.The messenger RNA levels of two of them,Ap.SPLP and Ap_VP,were upregulated by Gram-positive bacterium Staphylococcus aureus and fungus Beauveha bassiana infections.Double-stranded RNA-based expression knockdown of these two genes resulted in reduced PO activity of the aphid hemolymph,higher loads of S.aureus and B.bassiana in the aphids,and lower survival rates of the aphids after infections.Our data suggest that Ap.SPLP and Ap_VP are involved in PPO activation pathway in the pea aphid.展开更多
The pea aphid Acyrthosiphon pisum hosts different facultative symbionts(FS)which provide it with various benefits,such as tolerance to heat or protection against natural enemies(e.g.,fungi,parasitoid wasps).Here,we in...The pea aphid Acyrthosiphon pisum hosts different facultative symbionts(FS)which provide it with various benefits,such as tolerance to heat or protection against natural enemies(e.g.,fungi,parasitoid wasps).Here,we investigated whether and how the presence of certain FS could affect phenoloxidase(PO)activity,a key component of insect innate immunity,under normal and stressed conditions.For this,we used clones of A.pisum of difTerent genetic backgrounds(LLOl,YR2 and T3-8V1)lacking FS or harboring one or two(Regiella insecticola,Hamiltonella defensa,Serratia symbiotica Rickettsiella viridis).Gene expression and proteomics analyses of the aphid hemolymph indicated that the two A.pisum POs,PPOl and PP02,are expressed and translated into proteins.The level of PPO genes expression as well as the amount of PPO proteins and phenoloxidase activity in the hemolymph depended on both the aphid genotype and FS species.In particular,H.defensa and R.insecticola,but not S.symbiotica-h R.viridis,caused a sharp decrease in PO activity by interfering with both transcription and translation.The microinjection of different types of stressors(yeast,Escherichia coli,latex beads)in the YR2 lines hosting different symbionts affected the survival rate of aphids and,in most cases,also decreased the expression of PPO genes after 24 h.The amount and activity of PPO proteins varied according to the type of FS and stressor,without clear corresponding changes in gene expression.These data demonstrate that the presence of certain FS influences an important component of pea aphid immunity.展开更多
Carotenoids are involved in many essential physiological functions and are produced from geranylgeranyl pyrophosphate through synthase,desaturase,and cyclase activities.In the pea aphid(Acyrthosiphon pisum),the duplic...Carotenoids are involved in many essential physiological functions and are produced from geranylgeranyl pyrophosphate through synthase,desaturase,and cyclase activities.In the pea aphid(Acyrthosiphon pisum),the duplication of carotenoid biosynthetic genes,including carotenoid synthases/cyclases(ApCscA-C)and desaturases(ApCdeA-D),through horizontal gene transfer from fungi has been detected,and ApCdeB has known dehydrogenation functions.However,whether other genes contribute to aphid carotenoid biosynthesis,and its specific regulatory pathway,remains unclear.In the current study,functional analyses of seven genes were performed using heterologous complementation and RNA interference assays.The bifunctional enzymes ApCscA-C were responsible for the synthase of phytoene,and ApCscC may also have a cyclase activity.ApCdeA,ApCdeC,and ApCdeD had diverse dehydrogenation functions.ApCdeA catalyzed the enzymatic conversion of phytoene to neurosporene(three-step product),ApCdeC catalyzed the enzymatic conversion of phytoene to ζ-carotene(two-step product),and ApCdeD catalyzed the enzymatic conversion of phytoene to lycopene(four-step product).Silencing of ApCscs reduced the expression levels of ApCdes,and silencing these carotenoid biosynthetic genes reduced the α-,β-,and γ-carotene levels,as well as the total carotenoid level.The results suggest that these genes were activated and led to carotenoid biosynthesis in the pea aphid.展开更多
地下害虫和地上害虫虽然在空间上隔离,但植物作为媒介将它们联系到一个系统,为了探讨地下害虫危害对地上害虫的影响,本文利用蚕豆植株作为媒介,研究了韭菜迟眼蕈蚊Bradysia odoriphaga Yang et Zhang危害蚕豆植株对两种色型豌豆蚜Acyrth...地下害虫和地上害虫虽然在空间上隔离,但植物作为媒介将它们联系到一个系统,为了探讨地下害虫危害对地上害虫的影响,本文利用蚕豆植株作为媒介,研究了韭菜迟眼蕈蚊Bradysia odoriphaga Yang et Zhang危害蚕豆植株对两种色型豌豆蚜Acyrthosiphon pisum的影响。结果表明:韭菜迟眼蕈蚊危害改变了蚕豆植株的营养组成,包括干重和鲜重比、可溶性蛋白、可溶性糖、海藻糖和游离氨基酸。豌豆蚜取食后若虫历期延长,两种色型豌豆蚜1龄历期延长最为显著,红色型豌豆蚜3龄历期延长差异显著,其他各龄历期无差异;豌豆蚜若虫的死亡率提高,绿色型豌豆蚜1龄和2龄的死亡率高于对照组,红色型豌豆蚜2龄、3龄和4龄的死亡率高于对照组,其中红色型豌豆蚜2龄死亡率显著高于对照组;韭菜迟眼蕈蚊危害减小两种色型豌豆蚜每天产蚜数、10d累积产蚜数、净增值率、内禀增长率、周限增长率、相对生长率、体长和体重,平均世代周期延长但是无显著差异。结果表明,韭菜迟眼蕈蚊危害可直接影响蚕豆的营养组成,进一步间接影响豌豆蚜的生长发育。展开更多
Facultative bacterial endosymbionts in insects have been under intense study during the last years. Endosymbionts can modify the insect＇s phenotype, conferring adap- tive advantages under environmental stress. This s...Facultative bacterial endosymbionts in insects have been under intense study during the last years. Endosymbionts can modify the insect＇s phenotype, conferring adap- tive advantages under environmental stress. This seems particularly relevant for a group of worldwide agricultural aphid pests, because endosymbionts modify key fitness-related traits, including host plant use, protection against natural enemies and heat tolerance. Aimed to understand the role of facultative endosymbionts on the success of introduced aphid pests, the distribution and abundance of 5 facultative endosymbionts （Hamiltonella defensa, Regiella insecticola, Serratia symbiotica, Rickettsia and Spiroplasma） were stud- ied and compared in 4 cereal aphids （Sitobion avenae, Diuraphis noxia, Metopolophium dirhodum and Schizaphis graminium） and in the pea aphid Acyrthosiphon pisum complex from 2 agroclimatic zones in Chile. Overall, infections with faeultative endosymbionts exhibited a highly variable and characteristic pattern depending on the aphid species/host race and geographic zone, which could explain the success of aphid pest populations after their introduction. While S. symbiotica and H. defensa were the most frequent endosym- bionts carried by the A. pisum pea-race and A. pisum alfalfa-race aphids, respectively, the most frequent facultative endosymbiont carried by all cereal aphids was R. insecticola. Interestingly, a highly variable composition of endosymbionts carried by S. avenae was also observed between agroclimatic zones, suggesting that endosymbionts are responding differentially to abiotic variables （temperature and precipitations）. In addition, our findings constitute the first report of bacterial endosymbionts in cereal aphid species not screened before, and also the first report of aphid endosymbionts in Chile.展开更多
Aphids are important agricultural pests,vectors of many plant viruses and have sophisticated relationships with symbiotic microorganisms.Abundant asymptomatic RNA viruses have been reported in aphids due to the applic...Aphids are important agricultural pests,vectors of many plant viruses and have sophisticated relationships with symbiotic microorganisms.Abundant asymptomatic RNA viruses have been reported in aphids due to the application of RNA-seq,but aphid-virus interactions remain unclear.Bunyavirales is the most abundant RNA virus order,which can infect mammals,arthropods,and plants.However,many bunyaviruses have specific hosts,such as insects.Here,we discovered 18 viruses from 10 aphid species by RNA-seq.Importantly,a widespread presence bunyavirus,Aphid bunyavirus 1(ABV-1),was determined to have a wide host range,infecting and replicating in all 10 tested aphid species.ABV-1 may be transmitted horizontally during feeding on plant leaves and vertically through reproduction.In a comparison of the physiological parameters of ABV-1high and ABV-1low strains of pea aphid,higher ABV-1 titers reduced the total nymphal duration and induced the reproduction.Moreover,viral titer significantly affected the lipid and protein contents in pea aphids.In summary,we proposed that ABV-1 may have stable symbiont-like relationships with aphids,and these observations may provide a new direction for studying bunyaviruses in aphids and establishing a model for virus-aphid interactions.展开更多
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.31772533 and 31670659)the State Key Laboratory of Integrated Management of Pest Insects and Rodents(Grant No.Chinese IPM1717).
文摘Cuticular hydrocarbons form a barrier that protects terrestrial insects from water loss via the epicuticle.Lipophorin loads and transports lipids,including hydrocarbons,from one tissue to another.In some insects,the lipophorin receptor(LpR),which binds to lipophorin and accepts its lipid cargo,is essential for female fecundity because it mediates the incorporation of lipophorin by developing oocytes.However,it is unclear whether LpR is involved in the accumulation of cuticular hydrocarbons and its precise role in aphid reproduction remains unknown.We herein present the results of our molecular characterization,phylogenetic analysis,and functional annotation of the pea aphid(Acyrthosiphon pisum)LpR gene(ApLpR).This gene was transcribed throughout the A.pisum life cycle,but especially during the embryonic stage and in the abdominal cuticle.Furthermore,we optimized the RHA interference(RNAi)parameters by determining the ideal dose and duration for gene silencing in the pea aphid.We observed that the RNAi-based ApLpR suppression significantly decreased the internal and cuticular hydrocarbon contents as well as adult fecundity.Additionally,a deficiency in cuticular hydrocarbons increased the susceptibility of aphids to desiccation stress,with decreased survival rates under simulated drought conditions.Moreover,ApLpR expression levels significantly increased in response to the desiccation treatment.These results confirm that ApLpR is involved in transporting hydrocarbons and protecting aphids from desiccation stress.Furthermore,this gene is vital for aphid reproduction.Therefore,the ApLpR gene of A.pisum may be a novel RNAi target relevant for insect pest management.
基金This work was financially supported by the National Natural Science Foundation of China grant 31772530Natural Science Foundation of Shaanxi Province(2017JM3003)to ZL.
文摘Phenoloxidases(POs)are required for the pea aphid s defense against bacterial and fungal infection.Prophenoloxidases(PPOs)are protcolytically converted to its active form PO through a clip domain serine protease cascade.In this study,we identified five clip domain serine proteases in the pea aphids.The messenger RNA levels of two of them,Ap.SPLP and Ap_VP,were upregulated by Gram-positive bacterium Staphylococcus aureus and fungus Beauveha bassiana infections.Double-stranded RNA-based expression knockdown of these two genes resulted in reduced PO activity of the aphid hemolymph,higher loads of S.aureus and B.bassiana in the aphids,and lower survival rates of the aphids after infections.Our data suggest that Ap.SPLP and Ap_VP are involved in PPO activation pathway in the pea aphid.
基金funded by the China Scholarship Council(grant number:201506300039)supported by the French Government through the "Investments for the Future" programs LABEX SIGNALIFE ANR-ll-LABX-0028-01 and IDEX UCAJedi ANR-15-IDEX-01.
文摘The pea aphid Acyrthosiphon pisum hosts different facultative symbionts(FS)which provide it with various benefits,such as tolerance to heat or protection against natural enemies(e.g.,fungi,parasitoid wasps).Here,we investigated whether and how the presence of certain FS could affect phenoloxidase(PO)activity,a key component of insect innate immunity,under normal and stressed conditions.For this,we used clones of A.pisum of difTerent genetic backgrounds(LLOl,YR2 and T3-8V1)lacking FS or harboring one or two(Regiella insecticola,Hamiltonella defensa,Serratia symbiotica Rickettsiella viridis).Gene expression and proteomics analyses of the aphid hemolymph indicated that the two A.pisum POs,PPOl and PP02,are expressed and translated into proteins.The level of PPO genes expression as well as the amount of PPO proteins and phenoloxidase activity in the hemolymph depended on both the aphid genotype and FS species.In particular,H.defensa and R.insecticola,but not S.symbiotica-h R.viridis,caused a sharp decrease in PO activity by interfering with both transcription and translation.The microinjection of different types of stressors(yeast,Escherichia coli,latex beads)in the YR2 lines hosting different symbionts affected the survival rate of aphids and,in most cases,also decreased the expression of PPO genes after 24 h.The amount and activity of PPO proteins varied according to the type of FS and stressor,without clear corresponding changes in gene expression.These data demonstrate that the presence of certain FS influences an important component of pea aphid immunity.
基金This study was supported by the National Natural Science Foundation of China(32001908 and 32020103010)the Natural Science Foundation of Chongqing,China(cstc2020jcyj-msxmX0338)the Foundation Project of Southwest University(SWU019033).
文摘Carotenoids are involved in many essential physiological functions and are produced from geranylgeranyl pyrophosphate through synthase,desaturase,and cyclase activities.In the pea aphid(Acyrthosiphon pisum),the duplication of carotenoid biosynthetic genes,including carotenoid synthases/cyclases(ApCscA-C)and desaturases(ApCdeA-D),through horizontal gene transfer from fungi has been detected,and ApCdeB has known dehydrogenation functions.However,whether other genes contribute to aphid carotenoid biosynthesis,and its specific regulatory pathway,remains unclear.In the current study,functional analyses of seven genes were performed using heterologous complementation and RNA interference assays.The bifunctional enzymes ApCscA-C were responsible for the synthase of phytoene,and ApCscC may also have a cyclase activity.ApCdeA,ApCdeC,and ApCdeD had diverse dehydrogenation functions.ApCdeA catalyzed the enzymatic conversion of phytoene to neurosporene(three-step product),ApCdeC catalyzed the enzymatic conversion of phytoene to ζ-carotene(two-step product),and ApCdeD catalyzed the enzymatic conversion of phytoene to lycopene(four-step product).Silencing of ApCscs reduced the expression levels of ApCdes,and silencing these carotenoid biosynthetic genes reduced the α-,β-,and γ-carotene levels,as well as the total carotenoid level.The results suggest that these genes were activated and led to carotenoid biosynthesis in the pea aphid.
文摘地下害虫和地上害虫虽然在空间上隔离,但植物作为媒介将它们联系到一个系统,为了探讨地下害虫危害对地上害虫的影响,本文利用蚕豆植株作为媒介,研究了韭菜迟眼蕈蚊Bradysia odoriphaga Yang et Zhang危害蚕豆植株对两种色型豌豆蚜Acyrthosiphon pisum的影响。结果表明:韭菜迟眼蕈蚊危害改变了蚕豆植株的营养组成,包括干重和鲜重比、可溶性蛋白、可溶性糖、海藻糖和游离氨基酸。豌豆蚜取食后若虫历期延长,两种色型豌豆蚜1龄历期延长最为显著,红色型豌豆蚜3龄历期延长差异显著,其他各龄历期无差异;豌豆蚜若虫的死亡率提高,绿色型豌豆蚜1龄和2龄的死亡率高于对照组,红色型豌豆蚜2龄、3龄和4龄的死亡率高于对照组,其中红色型豌豆蚜2龄死亡率显著高于对照组;韭菜迟眼蕈蚊危害减小两种色型豌豆蚜每天产蚜数、10d累积产蚜数、净增值率、内禀增长率、周限增长率、相对生长率、体长和体重,平均世代周期延长但是无显著差异。结果表明,韭菜迟眼蕈蚊危害可直接影响蚕豆的营养组成,进一步间接影响豌豆蚜的生长发育。
文摘Facultative bacterial endosymbionts in insects have been under intense study during the last years. Endosymbionts can modify the insect＇s phenotype, conferring adap- tive advantages under environmental stress. This seems particularly relevant for a group of worldwide agricultural aphid pests, because endosymbionts modify key fitness-related traits, including host plant use, protection against natural enemies and heat tolerance. Aimed to understand the role of facultative endosymbionts on the success of introduced aphid pests, the distribution and abundance of 5 facultative endosymbionts （Hamiltonella defensa, Regiella insecticola, Serratia symbiotica, Rickettsia and Spiroplasma） were stud- ied and compared in 4 cereal aphids （Sitobion avenae, Diuraphis noxia, Metopolophium dirhodum and Schizaphis graminium） and in the pea aphid Acyrthosiphon pisum complex from 2 agroclimatic zones in Chile. Overall, infections with faeultative endosymbionts exhibited a highly variable and characteristic pattern depending on the aphid species/host race and geographic zone, which could explain the success of aphid pest populations after their introduction. While S. symbiotica and H. defensa were the most frequent endosym- bionts carried by the A. pisum pea-race and A. pisum alfalfa-race aphids, respectively, the most frequent facultative endosymbiont carried by all cereal aphids was R. insecticola. Interestingly, a highly variable composition of endosymbionts carried by S. avenae was also observed between agroclimatic zones, suggesting that endosymbionts are responding differentially to abiotic variables （temperature and precipitations）. In addition, our findings constitute the first report of bacterial endosymbionts in cereal aphid species not screened before, and also the first report of aphid endosymbionts in Chile.
基金This research was supported by National Natural Sci-ence Foundation(32072423)National Natural Science Foundation of China-Major International(Regional)Joint Research Project(32020103010)+1 种基金111 Project(B18044)the Foundation Project of Southwest University(SWU019033).We thank Dr Bi-Yue Ding(Academy of Agricultural Sciences.Southwest Univer-sity)for the technical assistance in western bloting.The Ap-Uny colony and Ap-Efr colony were kindly pro-vided by Professors Tong-Xian Liu and Giuy Smagghe,respectively.
文摘Aphids are important agricultural pests,vectors of many plant viruses and have sophisticated relationships with symbiotic microorganisms.Abundant asymptomatic RNA viruses have been reported in aphids due to the application of RNA-seq,but aphid-virus interactions remain unclear.Bunyavirales is the most abundant RNA virus order,which can infect mammals,arthropods,and plants.However,many bunyaviruses have specific hosts,such as insects.Here,we discovered 18 viruses from 10 aphid species by RNA-seq.Importantly,a widespread presence bunyavirus,Aphid bunyavirus 1(ABV-1),was determined to have a wide host range,infecting and replicating in all 10 tested aphid species.ABV-1 may be transmitted horizontally during feeding on plant leaves and vertically through reproduction.In a comparison of the physiological parameters of ABV-1high and ABV-1low strains of pea aphid,higher ABV-1 titers reduced the total nymphal duration and induced the reproduction.Moreover,viral titer significantly affected the lipid and protein contents in pea aphids.In summary,we proposed that ABV-1 may have stable symbiont-like relationships with aphids,and these observations may provide a new direction for studying bunyaviruses in aphids and establishing a model for virus-aphid interactions.
