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1.
‘Candidatus Liberibacter asiaticus’ (CLas), the bacterial pathogen associated with citrus greening disease, is transmitted by Diaphorina citri, the Asian citrus psyllid. Interactions among D. citri and its microbial endosymbionts, including ‘Candidatus Profftella armatura’, are likely to impact transmission of CLas. We used quantitative mass spectrometry to compare the proteomes of CLas(+) and CLas(-) populations of D. citri, and found that proteins involved in polyketide biosynthesis by the endosymbiont Profftella were up-regulated in CLas(+) insects. Mass spectrometry analysis of the Profftella polyketide diaphorin in D. citri metabolite extracts revealed the presence of a novel diaphorin-related polyketide and the ratio of these two polyketides was changed in CLas(+) insects. Insect proteins differentially expressed between CLas(+) and CLas(-) D. citri included defense and immunity proteins, proteins involved in energy storage and utilization, and proteins involved in endocytosis, cellular adhesion, and cytoskeletal remodeling which are associated with microbial invasion of host cells. Insight into the metabolic interdependence between the insect vector, its endosymbionts, and the citrus greening pathogen reveals novel opportunities for control of this disease, which is currently having a devastating impact on citrus production worldwide.  相似文献   

2.
Huanglongbing (HLB) is the most destructive disease of citrus worldwide. The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is the vector of the phloem‐inhabiting bacterium, Candidatus Liberibacter asiaticus, which is presumed to cause HLB in Florida citrus. Laboratory and field studies were conducted to examine the behavioral responses of male and female D. citri to their cuticular extracts. In olfactometer assays, more male D. citri were attracted to one, five, or 10 female cuticular extract equivalent units than blank controls. The results were confirmed in field studies in which clear or yellow traps baited with 10 female cuticular extract equivalent units attracted proportionately more males than clear traps baited with male cuticular extract or unbaited traps. Analyses of cuticular constituents of male and female D. citri revealed differences between the sexes in chemical composition of their cuticular extracts. Laboratory bioassays with synthetic chemicals identified from cuticular extracts indicated that dodecanoic acid attracted more males than clean air. Traps baited with dodecanoic acid did not increase total catch of D. citri as compared with blank traps at the dosages tested; however, the sex ratio of psyllid catch was male biased on traps baited with the highest lure loading dosage tested (10.0 mg).  相似文献   

3.
4.
Huanglongbing (HLB), also known as citrus greening, is currently the most destructive disease of citrus, responsible for huge economic losses in the world's major citrus production areas. The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), transmits ‘Candidatus Liberibacter asiaticus’ (Clas), the pathogen responsible to cause HLB. Understanding of vector, pathogen, and host plant interactions is important for the management of this vector‐disease complex. We used the direct‐current electrical penetration graph (DC‐EPG) system to evaluate feeding behavior of Clas‐infected D. citri adults, and their potential to transmit the pathogen to healthy citrus, Citrus reticulata Blanco cv. Sunki (Rutaceae), following a 24‐h inoculation access period. Plants were tested for the presence of Clas by qPCR 6 months after inoculation. Findings suggest that inoculation was associated with salivation into the phloem sieve elements (waveform E1). The minimum feeding time for successful transmission by a single adult was 88.8 min, with a minimum E1 duration of 5.1 min. Regression analysis indicated a significant relationship between E1 duration and transmission efficiency. The adults successful in transmitting Clas to healthy citrus were able to penetrate and feed in the phloem much earlier than those which did not transmit. The minimum duration of E1 for a female was shorter than that of a male, but transmission was higher. However, durations of other EPG parameters were not significantly different between male and female. Feeding by single Clas‐infected D. citri adults on 6‐month‐old plants (Sunki) resulted in 23% HLB‐positive plants 6 months after inoculation. Multiple nymphs or adults could transmit the pathogen more efficiently than individual adults in the field, and further enhance the severity of the disease. Effective tactics are warranted to control D. citri and disrupt transmission of Clas.  相似文献   

5.
Asian citrus psyllid Diaphorina citri is the vector of the citrus Huanglongbing (HLB) associated bacterial agent ‘Candidatus Liberibacter asiaticus’ (CLas). The molecular interactions between CLas and D. citri remain unclear. In the present study, protein profiles of mitochondrial, microsomal and cytosolic fractions from uninfected and CLas‐infected adult D. citri are investigated using two‐dimensional gel electrophoresis. The comparative analysis reveals a total of 18, 24 and 20 protein spots that are unique or differentially expressed in mitochondrial, microsomal and cytosolic proteins fractions respectively. These proteins are successfully identified by mass spectrometry. Among the 62 identified proteins, 30 are up‐regulated, whereas 32 are down‐regulated. These proteins include important components in energy metabolism such as ATP synthase, ATPase, ATP/ADP carrier protein, etc.; host stress responses such as heat shock proteins; host detoxification processes (i.e., cytochrome P450 and glutathione S‐transferase); and the cytoskeleton (such as actin, tubulin, myosin and tropomyosin). These data suggest that, after CLas infection, several proteins of D. citri, especially energy metabolism and protein biosynthesis, are altered, and extensive host defence responses are induced. In conclusion, the present study reports proteomic information that is helpful in understanding the vector–pathogen relationship between CLas and D. citri, and could be used to identify potential targets for limiting the spread of CLas, as well as to provide new insights into HLB management.  相似文献   

6.
The Asian citrus psyllid, Diaphorina citri Kuwayama, is among the most important pests of citrus. It is the main vector of the Huanglongbing (HLB) pathogen Candidatus Liberibacter asiaticus (CLas), which causes severe losses in citrus crops. Control of D. citri is therefore of paramount importance to reduce the spread of HLB. In this regard, using RNA interference (RNAi) to silence target genes is a useful strategy to control psyllids. In this study, using RNAi, we examined the biological functions of the V-ATPase subunit E (V-ATP-E) gene of D. citri, including its effect on acquisition of CLas. The amino acid sequence of V-ATP-E from D. citri had high homology with proteins from other insects. V-ATP-E was expressed at all D. citri life stages analyzed, and the expression level in mature adults was higher than that of teneral adults. Silencing of V-ATP-E resulted in a significant increase in mortality, reduced body weight, and induced cell apoptosis of the D. citri midgut. The reduced expression of V-ATP-E was indicated to inhibit CLas passing through the midgut and into the hemolymph, leading to a majority of CLas being confined to the midgut. In addition, double-stranded RNA of D. citri V-ATP-E was safe to non-target parasitic wasps. These results suggest that V-ATP-E is an effective RNAi target that can be used in D. citri control to block CLas infection.  相似文献   

7.
The Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Liviidae) is an insect vector that transmits the bacterial pathogen Candidatus Liberibacter asiaticus (CLas) associated with the destructive citrus disease, citrus huanglongbing (HLB). Currently, D. citri is the major target in HLB management, although insecticidal control and disruption of the D. citri–CLas interactions both face numerous challenges. The present study reports the subcellular proteomic profiles of D. citri, encompassing the three main subcellular protein fractions: cytosol, mitochondria and microsomes. After optimization, subcellular proteins of both high and low abundance are obtained by two‐dimensional gel electrophoresis (2‐DE). A total of 1170 spots are detected in the 2‐DE gels of the three subcellular fractions. One hundred and sixty‐four differentially expressed proteins are successfully identified using liquid chromatography‐dual mass spectroscopy. An efficient protocol for subcellular protein fractionation from D. citri is established and a clear protein separation is achieved with the chosen protein fractionation protocol. The identified cytosolic proteins are mainly metabolic enzymes, whereas a large portion of the identified proteins in the mitochondrial and microsomal fractions are involved in ATP biosynthesis and protein metabolism, respectively. Protein–protein interaction networks are predicted for some identified proteins known to be implicated in pathogen–vector interactions, such as actin, tubulin and ATP synthase, as well as insecticide resistance, such as the cytochrome P450 superfamily. The findings should provide useful information to help identify the mechanism responsible for the CLas–D. citri interactions and eventually contribute to D. citri control.  相似文献   

8.
The Asian citrus psyllid, Diaphorina citri Kuwayama, vectors the causal pathogen of huanglongbing (HLB), which is likely the most important disease affecting worldwide citrus production. Interplanting citrus with guava, Psidium guajava L., was reported to reduce D. citri populations and incidence of HLB. We describe a series of investigations on the response of D. citri to citrus volatiles with and without guava leaf volatiles and to synthetic dimethyl disulphide (DMDS), in laboratory olfactometers and in the field. Volatiles from guava leaves significantly inhibited attraction of D. citri to normally attractive host‐plant (citrus) volatiles. A similar level of inhibition was recorded when synthetic DMDS was co‐released with volatiles from citrus leaves. In addition, the volatile mixture emanating from a combination of intact citrus and intact guava leaves induced a knock‐down effect on adult D. citri. Compounds similar to DMDS including dipropyl disulphide, ethyl‐1‐propyl disulphide, and diethyl disulphide did not affect the behavioural response of D. citri to attractive citrus host plant volatiles. Head‐space volatile analyses were conducted to compare sulphur volatile profiles of citrus and guava, used in our behavioural assays, with a gas chromatography‐pulsed flame photometric detector. DMDS, produced by wounded guava in our olfactometer assays, was not produced by similarly wounded citrus. The airborne concentration of DMDS that induced the behavioural effect in the 4‐choice olfactometer was 107 pg/ml. In a small plot field experiment, populations of D. citri were significantly reduced by deployment of synthetic DMDS from polyethylene vials compared with untreated control plots. Our results verify that guava leaf volatiles inhibit the response of D. citri to citrus host plant volatiles and suggest that the induced compound, DMDS, may be partially responsible for this effect. Also, we show that field deployment of DMDS reduces densities of D. citri and thus may have potential as a novel control strategy.  相似文献   

9.
10.
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.  相似文献   

11.
The Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Liviidae) is a damaging pest of citrus globally and has recently been detected in Tanzania. Although direct damage by the pest is seldom of economic importance, the insect is more notorious for its ability to vector the fastidious phloem-limited bacterium Candidatus Liberibacter asiaticus (CLas), the putative causal bacterium of Huanglongbing or Asian citrus greening disease. For many years, Trioza erytreae (Del Guercio) (Hemiptera: Triozidae) was known to be the main vector of the African citrus greening disease caused by Candidatus Liberibacter africanus (CLaf), but the recent arrival of D. citri on the continent adds to the dynamics of infection and spread of both diseases on mainland Africa. Following the recent report of the presence of D. citri in Tanzania, an additional delimiting survey was carried out in the region, focusing on Kenya, mainland Tanzania and Zanzibar to detect the presence and ascertain the extent of spread of D. citri. We employed molecular tools based on the use of DNA barcoding to confirm the identity of D. citri. In addition to D. citri, the occurrence of T. erytreae in the same sampling locations is also reported. Adults and nymphs of either D. citri or T. erytreae were collected from citrus at many of the surveyed sites ranging from 19 to 668 m above sea level (masl) in Tanzania, 20–1666 masl in Kenya, and 42–48 masl in Zanzibar. Diaphorina citri was sympatric with T. erytreae at the mid to higher elevations of 1375–1666 masl and no T. erytreae or its open-gall symptoms were detected below 523 masl. Sequences obtained were queried via BLAST and all linked to D. citri of different accession numbers already available on GenBank. This is the first report of the presence of D. citri in Kenya and Zanzibar. The potential implication of the detection and spread of the two pathogens, CLaf and CLas to the citrus industry in East Africa and movement of suitable host plants is discussed.  相似文献   

12.
The Asian citrus psyllid (AsCP), Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is a highly competent vector of the phloem-inhabiting bacterium Candidatus Liberibacter asiaticus associated with the citrus disease huanglongbing (HLB). Commonly referred to as citrus greening disease in the USA, HLB causes reduced fruit yields, quality, and ultimately tree death and is considered the most serious citrus disease. HLB has become a major limiting factor to the production of citrus worldwide. Studies of HLB have been impeded by the fact that C. Liberibacter has not yet been cultured on artificial nutrient media. After being acquired by a psyllid, C. Liberibacter asiaticus is reported to replicate within the psyllid and is retained by the psyllid throughout its life span. We therefore hypothesized that C. Liberibacter asiaticus could be cultured in vitro using psyllid cell cultures as the medium and investigated the establishment of a pure culture for AsCP cells. Several commercially available insect cell culture media along with some media we developed were screened for viability to culture cells from AsCP embryos. Cells from psyllid tissues adhered to the plate and migration was observed within 24 h. Cells were maintained at 20°C. We successfully established primary psyllid cell cultures, referred to as DcHH-1, for D. citri Hert-Hunter-1, with a new media, Hert-Hunter-70.  相似文献   

13.
Citrus greening (Huanglongbing, HLB) is a destructive disease associated with the uncultivable, phloem-limited, gram-negative bacteria Candidatus Liberibacter spp., which affects citrus crops and other Rutaceae species. HLB is rapidly transmitted by the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae). We developed an artificial medium on which D. citri eggs can hatch and first-instar nymphs can feed. The medium could be used to study insect physiology and screen molecules that may interfere with egg hatching and nymph development.  相似文献   

14.
Huanglongbing is known as a destructive disease in citrus production. Investigation on plant response and development of huanglongbing disease against heat treatment on ‘Siam Purworejo’ (Citrus nobilis (Lour)) and ‘Nambangan’ (C. maxima (Burm.) Merr.) was done. High-temperature treatment was applied by covering plants with an enclosed screen. The treatment plant has three types of CLas pathogen infection status. The result showed that heat treatments could significantly increase new flushes. It was found that intensity of HLB infected plant decreased. The treatments effect on the proline level was dependent on cultivar, leaves age and HLB-infection status. Chlorophyll content of HLB infected plants increased due to high temperature. High-temperature increased Fe content in the artificially infected plant, whereas Zn contents increased in the leaves of infected plants by vector. ‘Nambangan’ had higher Fe content than ‘Siam Purworejo’ on uncovered plants. CLas bacteria still persisted in infected plant based on real-time PCR analysis.  相似文献   

15.
16.
The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is an important insect pest of citrus. It is the vector of ‘Candidatus’ Liberibacter asiaticus, a phloem‐limited bacterium that infects citrus, resulting in the disease Huanglongbing (HLB). Disease management relies heavily on suppression of D. citri populations with insecticides, including pyrethroids. In recent annual surveys to monitor insecticide resistance, reduced susceptibility to fenpropathrin was identified in several field populations of D. citri. The primary target of pyrethroids is the voltage‐gated sodium channel (VGSC). The VGSC is prone to target‐site insensitivity because of mutations that either reduce pyrethroid binding and/or alter gating kinetics. These mutations, known as knockdown resistance or kdr, have been reported in a wide diversity of arthropod species. Alternative splicing, in combination with kdr mutations, has been also associated with reduced pyrethroid efficacy. Here we report the molecular characterization of the VGSC in D. citri along with a survey of alternative splicing across developmental stages of this species. Previous studies demonstrated that D. citri has an exquisite enzymatic arsenal to detoxify insecticides resulting in reduced efficacy. The results from the current investigation demonstrate that target‐site insensitivity is also a potential basis for insecticide resistance to pyrethroids in D. citri. The VGSC sequence and its molecular characterization should facilitate early elucidation of the underlying cause of an established case of resistance to pyrethroids. This is the first characterization of a VGSC from a hemipteran to this level of detail, with the majority of the previous studies on dipterans and lepidopterans.  相似文献   

17.
Asian citrus psyllid Diaphorina citri Kuwayama is extremely problematic worldwide, particularly where Huanglongbing (HLB) disease, the most serious and devastating of citrus diseases, is found. The threat is a result of its ability to transmit the causal agent of HLB, Candidatus Liberibacter asiaticus (CLas) bacterium. Improvements in proteomics, mass spectrometry, bioinformatics tools and gene ontology annotation facilitate the mapping and large‐scale identification and quantification of proteins. To date, only a few comparative proteomic studies report the developmental proteomic changes of hemimetabolous and plant–disease vector insects. Two‐dimensional gel electrophoresis analysis of D. citri total protein is able to detect qualitative and quantitative developmental differences. Liquid chromatography‐tandem mass spectrometry identifies 89 protein spots. Most proteins are metabolism and bioenergetics‐related. Nineteen protein spots are found to be implicated in stress/defence/immunity; 7 in development regulation; 9 in nervous system functions; 4 in the reproductive system; 23 in cytoskeleton and muscle organization; and 4 in movement, flight and other processes. Significant increases in the level of proteins related to structural constitution of the skeleton, stress/defence/immunity, reproduction system, muscles, locomotion and flight are found in adults, consistent with the fact that D. citri is a hemimetabolous insect, whereas proteins involved in developmental regulation are higher in the nymphal stage. The identification of these variably expressed proteins between the nymph and adult stages, linked with the basis of their physiological roles, will lead to a better understanding of the factors influencing development in D. citri and the regulation of some crucial metabolic pathways. It may also help to identify targets for genetic manipulation using RNA interference or other techniques to disrupt Asian citrus psyllid development, lifespan or its ability to transmit CLas.  相似文献   

18.
Tamarixia radiata Waterston (Hymenoptera: Eulophidae) is an effective idiobiont ectoparasitoid of the psyllid Diaphorina citri Kuwayama (Hemiptera: Psyllidae), vector of the huanglongbing (HLB). We examined the olfactory responses of T. radiata to volatiles emanating from D. citri or plant volatiles using a custom designed T-maze olfactometer and open arena bioassays. We also examined the behavioral response of male and female T. radiata to conspecifics of the opposite sex to determine whether olfactory signals mediate mate location. T. radiata adults exhibited a sexually dimorphic response to volatiles emanating from D. citri and citrus. Female T. radiata responded positively to the odors emanating from D. citri nymphs in both olfactometer and open arena bioassays. However, female wasps showed no response to odors emanating from D. citri adults, D. citri honey dew secretions, intact citrus or orange jasmine leaves. Odors emanating from D. citri damaged citrus were not attractive to T. radiata females but stimulated attraction of wasps to D. citri on damaged plants. T. radiata females were not attracted to D. citri immatures when they were presented as visual cues. Male T. radiata did not show attraction to D. citri nymphs or other putative odors that were attractive to female T. radiata. In olfactometer bioassays, more male T. radiata responded to the odor of female conspecifics than blank controls in the absence of associated citrus host plant volatiles. Odors emanating from female T. radiata were not attractive to male T. radiata. Male or female T. radiata were not attracted to the odors emanating from same sex conspecifics. Both male and female T. radiata adults showed positive phototactic behavior. Collectively, our results provide behavioral evidence that: 1) female T. radiata use volatiles emanating from D. citri nymphs to locate its host and: 2) female T. radiata release a volatile pheromone that attracts male conspecifics.  相似文献   

19.
Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is the principal vector of citrus greening (huanglongbing) disease. Invasion of new areas by the vector increases the risk of further spread of the disease and has economic impacts on the global citrus industry. Effective implementation of vector surveys is essential to contain disease outbreaks. This is especially true in countries such as Japan, where most of the major citrus‐producing areas are free from citrus greening. Recently, vector surveys have been routinely conducted to maintain ‘disease‐free’ and ‘disease‐ and vector‐free’ areas in Japan, and improvement of methods that can detect D. citri in native insect populations is imperative. Here, we developed a method of using conventional and real‐time PCR to detect D. citri among bulk insects captured in sticky traps without the need for preliminary differentiation steps based on morphology. DNA fragments of D. citri were specifically detected by both conventional and real‐time PCR in a mixture of a 10?3 dilution (ca. 0.008–0.009 ng/μl) of D. citriDNA and 100 ng/μl of bulk insect DNA, indicating that small body parts such as pieces of leg or parts of wings of D. citri were detectable in the bulk insect samples. No misleading amplification of fragments from the other psyllid species and citrus pests we used occurred under our PCR conditions. Our results suggest that the technique is applicable to extensive surveys of D. citri in early warning programmes.  相似文献   

20.
The Asian citrus psyllid, Diaphorina citri, is the insect vector of the causal agent of huanglongbing (HLB), a devastating bacterial disease of commercial citrus. Presently, few genomic resources exist for D. citri. In this study, we utilized PacBio HiFi and chromatin confirmation contact (Hi-C) sequencing to sequence, assemble, and compare three high-quality, chromosome-scale genome assemblies of D. citri collected from California, Taiwan, and Uruguay. Our assemblies had final sizes of 282.67 Mb (California), 282.89 Mb (Taiwan), and 266.67 Mb (Uruguay) assembled into 13 pseudomolecules—a reduction in assembly size of 41–45% compared with previous assemblies which we validated using flow cytometry. We identified the X chromosome in D. citri and annotated each assembly for repetitive elements, protein-coding genes, transfer RNAs, ribosomal RNAs, piwi-interacting RNA clusters, and endogenous viral elements. Between 19,083 and 20,357 protein-coding genes were predicted. Repetitive DNA accounts for 36.87–38.26% of each assembly. Comparative analyses and mitochondrial haplotype networks suggest that Taiwan and Uruguay D. citri are more closely related, while California D. citri are closely related to Florida D. citri. These high-quality, chromosome-scale assemblies provide new genomic resources to researchers to further D. citri and HLB research.  相似文献   

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