The Cuticle Protein Gene MPCP4 of Myzus persicae (Homoptera: Aphididae) Plays a Critical Role in Cucumber Mosaic Virus Acquisition

Transcriptomic and Proteomic Analyses of Myzus persicae Carrying Brassica Yellows Virus

Viruses in the genus Polerovirus infect a wide range of crop plants and cause severe economic crop losses. BrYV belongs to the genus Polerovirus and is transmitted by Myzus persicae. However, the changes in transcriptome and proteome profiles of M. persicae during viral infection are unclear. Here, RNA-Seq and TMT-based quantitative proteomic analysis were performed to compare the differences between viruliferous and nonviruliferous aphids. In total, 1266 DEGs were identified at the level of transcription with 980 DEGs being upregulated and 286 downregulated in viruliferous aphids. At the protein level, among the 18 DEPs identified, the number of upregulated proteins in viruliferous aphids was twice that of the downregulated DEPs. Enrichment analysis indicated that these DEGs and DEPs were mainly involved in epidermal protein synthesis, phosphorylation, and various metabolic processes. Interestingly, the expressions of a number of cuticle proteins and tubulins were upregulated in viruliferous aphids. Taken together, our study revealed the complex regulatory network between BrYV and its vector M. persicae from the perspective of omics. These findings should be of great benefit to screening key factors involved in the process of virus circulation in aphids and provide new insights for BrYV prevention via vector control in the field.

Insight into aphid mediated Potato Virus Y transmission: A molecular to bioinformatics prospective

Potato, the world's most popular crop is reported to provide a food source for nearly a billion people. It is prone to a number of biotic stressors that affect yield and quality, out of which Potato Virus Y (PVY) occupies the top position. PVY can be transmitted mechanically and by sap-feeding aphid vectors. The application of insecticide causes an increase in the resistant vector population along with detrimental effects on the environment; genetic resistance and vector-virus control are the two core components for controlling the deadly PVY. Using transcriptomic tools together with differential gene expression and gene discovery, several loci and genes associated with PVY resistance have been widely identified. To combat this virus we must increase our understanding on the molecular response of the PVY-potato plant-aphid interaction and knowledge of genome organization, as well as the function of PVY encoded proteins, genetic diversity, the molecular aspects of PVY transmission by aphids, and transcriptome profiling of PVY infected potato cultivars. Techniques such as molecular and bioinformatics tools can identify and monitor virus transmission. Several studies have been conducted to understand the molecular basis of PVY resistance/susceptibility interactions and their impact on PVY epidemiology by studying the interrelationship between the virus, its vector, and the host plant. This review presents current knowledge of PVY transmission, epidemiology, genome organization, molecular to bioinformatics responses, and its effective management.

The Effects of Cucumber Mosaic Virus and Its 2a and 2b Proteins on Interactions of Tomato Plants with the Aphid Vectors Myzus persicae and Macrosiphum euphorbiae

Cucumber mosaic virus (CMV), a major tomato pathogen, is aphid-vectored in the non-persistent manner. We investigated if CMV-induced volatile organic compounds (VOCs) or other virus-induced cues alter aphid-tomato interactions. Y-tube olfactometry showed that VOCs emitted by plants infected with CMV (strain Fny) attracted generalist (Myzus persicae) and Solanaceae specialist (Macrosiphum euphorbiae) aphids. Myzus persicae preferred settling on infected plants (3 days post-inoculation: dpi) at 1h post-release, but at 9 and 21 dpi, aphids preferentially settled on mock-inoculated plants. Macrosiphum euphorbiae showed no strong preference for mock-inoculated versus infected plants at 3 dpi but settled preferentially on mock-inoculated plants at 9 and 21 dpi. In darkness aphids showed no settling or migration bias towards either mock-inoculated or infected plants. However, tomato VOC blends differed in light and darkness, suggesting aphids respond to a complex mix of olfactory, visual, and other cues influenced by infection. The LS-CMV strain induced no changes in aphid-plant interactions. Experiments using inter-strain recombinant and pseudorecombinant viruses showed that the Fny-CMV 2a and 2b proteins modified tomato interactions with Macrosiphum euphorbiae and Myzus persicae, respectively. The defence signal salicylic acid prevents excessive CMV-induced damage to tomato plants but is not involved in CMV-induced changes in aphid-plant interactions.

Systems Biology of Virus-Host Protein Interactions: From Hypothesis Generation to Mechanisms of Replication and Pathogenesis

As obligate intracellular parasites, all viruses must co-opt cellular machinery to facilitate their own replication. Viruses often co-opt these cellular pathways and processes through physical interactions between viral and host proteins. In addition to facilitating fundamental aspects of virus replication cycles, these virus-host protein interactions can also disrupt physiological functions of host proteins, causing disease that can be advantageous to the virus or simply a coincidence. Consequently, unraveling virus-host protein interactions can serve as a window into molecular mechanisms of virus replication and pathogenesis. Identifying virus-host protein interactions using unbiased systems biology approaches provides an avenue for hypothesis generation. This review highlights common systems biology approaches for identification of virus-host protein interactions and the mechanistic insights revealed by these methods. We also review conceptual innovations using comparative and integrative systems biology that can leverage global virus-host protein interaction data sets to more rapidly move from hypothesis generation to mechanism. Expected final online publication date for the Annual Review of Virology, Volume 9 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

A Review on Transcriptional Responses of Interactions between Insect Vectors and Plant Viruses

This review provides a synopsis of transcriptional responses pertaining to interactions between plant viruses and the insect vectors that transmit them in diverse modes. In the process, it attempts to catalog differential gene expression pertinent to virus–vector interactions in vectors such as virus reception, virus cell entry, virus tissue tropism, virus multiplication, and vector immune responses. Whiteflies, leafhoppers, planthoppers, and thrips are the main insect groups reviewed, along with aphids and leaf beetles. Much of the focus on gene expression pertinent to vector–virus interactions has centered around whole-body RNA extraction, whereas data on virus-induced tissue-specific gene expression in vectors is limited. This review compares transcriptional responses in different insect groups following the acquisition of non-persistent, semi-persistent, and persistent (non-propagative and propagative) plant viruses and identifies parallels and divergences in gene expression patterns. Understanding virus-induced changes in vectors at a transcriptional level can aid in the identification of candidate genes for targeting with RNAi and/or CRISPR editing in insect vectors for management approaches.

Effect of aphid biology and morphology on plant virus transmission

Aphids severely affect crop production by transmitting many plant viruses. Viruses are obligate intracellular pathogens that mostly depend on vectors for their transmission and survival. A majority of economically important plant viruses are transmitted by aphids. They transmit viruses either persistently (circulative or non-circulative) or non-persistently. Plant virus transmission by insects is a process that has evolved over time and is strongly influenced by insect morphological features and biology. Over the past century, a large body of research has provided detailed knowledge of the molecular processes underlying virus-vector interactions. In this review, we discuss how aphid biology and morphology can affect plant virus transmission. © 2021 Society of Chemical Industry.

Potato leafroll virus reduces Buchnera aphidocola titer and alters vector transcriptome responses

Viruses in the Luteoviridae family, such as Potato leafroll virus (PLRV), are transmitted by aphids in a circulative and nonpropagative mode. This means the virions enter the aphid body through the gut when they feed from infected plants and then the virions circulate through the hemolymph to enter the salivary glands before being released into the saliva. Although these viruses do not replicate in their insect vectors, previous studies have demonstrated viruliferous aphid behavior is altered and the obligate symbiont of aphids, Buchnera aphidocola, may be involved in transmission. Here we provide the transcriptome of green peach aphids (Myzus persicae) carrying PLRV and virus-free control aphids using Illumina sequencing. Over 150 million paired-end reads were obtained through Illumina sequencing, with an average of 19 million reads per library. The comparative analysis identified 134 differentially expressed genes (DEGs) between the M. persicae transcriptomes, including 64 and 70 genes that were up- and down-regulated in aphids carrying PLRV, respectively. Using functional classification in the GO databases, 80 of the DEGs were assigned to 391 functional subcategories at category level 2. The most highly up-regulated genes in aphids carrying PLRV were cytochrome p450s, genes related to cuticle production, and genes related to development, while genes related to heat shock proteins, histones, and histone modification were the most down-regulated. PLRV aphids had reduced Buchnera titer and lower abundance of several Buchnera transcripts related to stress responses and metabolism. These results suggest carrying PLRV may reduce both aphid and Buchnera genes in response to stress. This work provides valuable basis for further investigation into the complicated mechanisms of circulative and nonpropagative transmission.

Infection of Arabidopsis by cucumber mosaic virus triggers jasmonate-dependent resistance to aphids that relies partly on the pattern-triggered immunity factor BAK1

Many aphid-vectored viruses are transmitted nonpersistently via transient attachment of virus particles to aphid mouthparts and are most effectively acquired or transmitted during brief stylet punctures of epidermal cells. In Arabidopsis thaliana, the aphid-transmitted virus cucumber mosaic virus (CMV) induces feeding deterrence against the polyphagous aphid Myzus persicae. This form of resistance inhibits prolonged phloem feeding but promotes virus acquisition by aphids because it encourages probing of plant epidermal cells. When aphids are confined on CMV-infected plants, feeding deterrence reduces their growth and reproduction. We found that CMV-induced inhibition of growth as well as CMV-induced inhibition of reproduction of M. persicae are dependent upon jasmonate-mediated signalling. BRASSINOSTEROID INSENSITIVE1-ASSOCIATED KINASE1 (BAK1) is a co-receptor enabling detection of microbe-associated molecular patterns and induction of pattern-triggered immunity (PTI). In plants carrying the mutant bak1-5 allele, CMV induced inhibition of M. persicae reproduction but not inhibition of aphid growth. We conclude that in wildtype plants CMV induces two mechanisms that diminish performance of M. persicae: a jasmonate-dependent and PTI-dependent mechanism that inhibits aphid growth, and a jasmonate-dependent, PTI-independent mechanism that inhibits reproduction. The growth of two crucifer specialist aphids, Lipaphis erysimi and Brevicoryne brassicae, was not affected when confined on CMV-infected A. thaliana. However, B. brassicae reproduction was inhibited on CMV-infected plants. This suggests that in A. thaliana CMV-induced resistance to aphids, which is thought to incentivize virus vectoring, has greater effects on polyphagous than on crucifer specialist aphids.

Analysis of the Role of Bradysia impatiens (Diptera: Sciaridae) as a Vector Transmitting Peanut Stunt Virus on the Model Plant Nicotiana benthamiana

Bradysia species, commonly known as fungus gnats, are ubiquitous in greenhouses, nurseries of horticultural plants, and commercial mushroom houses, causing significant economic losses. Moreover, the insects from the Bradysia genus have a well-documented role in plant pathogenic fungi transmission. Here, a study on the potential of Bradysia impatiens to acquire and transmit the peanut stunt virus (PSV) from plant to plant was undertaken. Four-day-old larvae of B. impatiens were exposed to PSV-P strain by feeding on virus-infected leaves of Nicotiana benthamiana and then transferred to healthy plants in laboratory conditions. Using the reverse transcription-polymerase chain reaction (RT-PCR), real-time PCR (RT-qPCR), and digital droplet PCR (RT-ddPCR), the PSV RNAs in the larva, pupa, and imago of B. impatiens were detected and quantified. The presence of PSV genomic RNA strands as well as viral coat protein in N. benthamiana, on which the viruliferous larvae were feeding, was also confirmed at the molecular level, even though the characteristic symptoms of PSV infection were not observed. The results have shown that larvae of B. impatiens could acquire the virus and transmit it to healthy plants. Moreover, it has been proven that PSV might persist in the insect body transstadially. Although the molecular mechanisms of virion acquisition and retention during insect development need further studies, this is the first report on B. impatiens playing a potential role in plant virus transmission.

Affinity Purification-Mass Spectrometry Identifies a Novel Interaction between a Polerovirus and a Conserved Innate Immunity Aphid Protein that Regulates Transmission Efficiency

The vast majority of plant viruses are transmitted by insect vectors, with many crucial aspects of the transmission process being mediated by key protein-protein interactions. Still, very few vector proteins interacting with viruses have been identified and functionally characterized. Potato leafroll virus (PLRV) is transmitted most efficiently by Myzus persicae, the green peach aphid, in a circulative, non-propagative manner. Using affinity purification coupled to high-resolution mass spectrometry (AP-MS), we identified 11 proteins from M. persicaedisplaying a high probability of interaction with PLRV and an additional 23 vector proteins with medium confidence interaction scores. Three of these aphid proteins were confirmed to directly interact with the structural proteins of PLRV and other luteovirid species via yeast two-hybrid. Immunolocalization of one of these direct PLRV-interacting proteins, an orthologue of the human innate immunity protein complement component 1 Q subcomponent-binding protein (C1QBP), shows that MpC1QBP partially co-localizes with PLRV in cytoplasmic puncta and along the periphery of aphid gut epithelial cells. Artificial diet delivery to aphids of a chemical inhibitor of C1QBP leads to increased PLRV acquisition by aphids and subsequently increased titer in inoculated plants, supporting a role for C1QBP in the acquisition and transmission efficiency of PLRV by M. persicae. This study presents the first use of AP-MS for the in vivo isolation of a functionally relevant insect vector-virus protein complex. MS data are available from ProteomeXchange.org using the project identifier PXD022167.

Combined Transcriptomic and Proteomic Analysis of Myzus persicae, the Green Peach Aphid, Infected with Cucumber Mosaic Virus

Simple Summary

In this study, an integrated analysis of the mRNA and protein was performed to identify important putative regulators involved in the transmission of CMV (cucumber mosaic virus) by aphids. At the level of transcription, a total of 20,550 genes (≥2-fold expression difference) were identified as being differentially expressed genes (DEGs) 24 h after healthy aphid transfer to infected tobacco plants using the RNA-seq approach. At the protein level, 744 proteins were classified as being differentially abundant between virus-treated and control Myzus persicae using iTRAQ (isobaric tags for relative and absolute quantitation) analysis. The combined mRNA and protein analysis enabled the identification of some viral putative regulators, such as cuticle proteins, ribosomal proteins, and cytochrome P450 enzymes. The results show that most of the key putative regulators were highly accumulated at the protein level. Based on those findings, we can speculate that the process by which aphids spread CMV is mainly related to post-translational regulation rather than transcription.

Abstract

Aphids transmit CMV (cucumber mosaic virus) in a non-persistent manner. However, little is known about the mechanism of CMV transmission. In this study, an integrated analysis of the mRNA and protein was performed to identify important putative regulators involved in the transmission of CMV by aphids. At the level of transcription, a total of 20,550 genes (≥2-fold expression difference) were identified as being differentially expressed genes (DEGs) 24 h after healthy aphid transfer to infected tobacco plants using the RNA-seq approach. At the protein level, 744 proteins were classified as being differentially abundant between virus-treated and control M. persicae using iTRAQ (isobaric tags for relative and absolute quantitation) analysis. The combined mRNA and protein analysis enabled the identification of some viral putative regulators, such as cuticle proteins, ribosomal proteins, and cytochrome P450 enzymes. The results show that most of the key putative regulators were highly accumulated at the protein level. Based on those findings, we can speculate that the process by which aphids spread CMV is mainly related to post-translational regulation rather than transcription.

Identification of Immune Response to Sacbrood Virus Infection in Apis cerana Under Natural Condition

Chinese sacbrood virus (CSBV) is a serious threat to eastern honeybees (Apis cerana), especially larvae. However, the pathological mechanism of this deadly disease remains unclear. Here, we employed mRNA and small RNA (sRNA) transcriptome approach to investigate the microRNAs (miRNAs) and small interfering RNAs (siRNAs) expression changes of A. cerana larvae infected with CSBV under natural condition. We found that serine proteases involved in immune response were down-regulated, while the expression of siRNAs targeted to serine proteases were up-regulated. In addition, CSBV infection also affected the expression of larvae cuticle proteins such as larval cuticle proteins A1A and A3A, resulting in increased susceptibility to CSBV infection. Together, our results provide insights into sRNAs that they are likely to be involved in regulating honeybee immune response.

Applications of Proteomic Tools to Study Insect Vector-Plant Virus Interactions

Proteins are crucial players of biological interactions within and between the organisms and thus it is important to understand the role of proteins in successful partnerships, such as insect vectors and their plant viruses. Proteomic approaches have identified several proteins at the interface of virus acquisition and transmission by their insect vectors which could be potential molecular targets for sustainable pest and viral disease management strategies. Here we review the proteomic techniques used to study the interactions of insect vector and plant virus. Our review will focus on the techniques available to identify the infection, global changes at the proteome level in insect vectors, and protein-protein interactions of insect vectors and plant viruses. Furthermore, we also review the integration of other techniques with proteomics and the available bioinformatic tools to analyze the proteomic data.

Transcriptome analysis of the immune response of silkworm at the early stage of Bombyx mori bidensovirus infection

Bombyx mori bidensovirus (BmBDV) infects silkworm midgut and causes chronic flacherie disease; however, the interaction between BmBDV and silkworm is unclear. Twenty-four hours after BmBDV infection, the midgut was extracted for RNA-seq to analyze the factors associated with BmBDV-invasion and the early antiviral immune response in silkworms. The total reads from each sample were more than 16100000 and the number of expressed genes exceeded 8200. There were 334 upregulated and 272 downregulated differentially expressed genes (DEGs). Gene ontology analysis of DEGs showed that structural constituents of cuticle, antioxidant, and immune system processes were upregulated. Further analysis revealed BmBDV-mediated induction of BmorCPR23 and BmorCPR44, suggesting possible involvement in viral invasion. Antioxidant genes that protect host cells from virus-induced oxidative stress, were significantly upregulated after BmBDV infection. Several genes related to peroxisomes, apoptosis, and autophagy-which may be involved in antiviral immunity-were induced by BmBDV. These results provide insights into the mechanism of BmBDV infection and host defense.

Soybean aphid biotype 1 genome: Insights into the invasive biology and adaptive evolution of a major agricultural pest

The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae) is a serious pest of the soybean plant, Glycine max, a major world-wide agricultural crop. We assembled a de novo genome sequence of Ap. glycines Biotype 1, from a culture established shortly after this species invaded North America. 20.4% of the Ap. glycines proteome is duplicated. These in-paralogs are enriched with Gene Ontology (GO) categories mostly related to apoptosis, a possible adaptation to plant chemistry and other environmental stressors. Approximately one-third of these genes show parallel duplication in other aphids. But Ap. gossypii, its closest related species, has the lowest number of these duplicated genes. An Illumina GoldenGate assay of 2380 SNPs was used to determine the world-wide population structure of Ap. Glycines. China and South Korean aphids are the closest to those in North America. China is the likely origin of other Asian aphid populations. The most distantly related aphids to those in North America are from Australia. The diversity of Ap. glycines in North America has decreased over time since its arrival. The genetic diversity of Ap. glycines North American population sampled shortly after its first detection in 2001 up to 2012 does not appear to correlate with geography. However, aphids collected on soybean Rag experimental varieties in Minnesota (MN), Iowa (IA), and Wisconsin (WI), closer to high density Rhamnus cathartica stands, appear to have higher capacity to colonize resistant soybean plants than aphids sampled in Ohio (OH), North Dakota (ND), and South Dakota (SD). Samples from the former states have SNP alleles with high F_ST values and frequencies, that overlap with genes involved in iron metabolism, a crucial metabolic pathway that may be affected by the Rag-associated soybean plant response. The Ap. glycines Biotype 1 genome will provide needed information for future analyses of mechanisms of aphid virulence and pesticide resistance as well as facilitate comparative analyses between aphids with differing natural history and host plant range.

Cuticular Structure Proteomics in the Pea Aphid Acyrthosiphon pisum Reveals New Plant Virus Receptor Candidates at the Tip of Maxillary Stylets

Aphids are phloem-feeding insects known as major pests in agriculture that are able to transmit hundreds of plant viruses. The majority of these viruses, classified as noncirculative, are retained and transported on the inner surface of the cuticle of the needle-like mouthparts while the aphids move from plant to plant. Identification of receptors of viruses within insect vectors is a key challenge because they are promising targets for alternative control strategies. The acrostyle, an organ discovered earlier within the common food/salivary canal at the tip of aphid maxillary stylets, displays proteins at the cuticle-fluid interface, some of which are receptors of noncirculative viruses. To assess the presence of stylet- and acrostyle-specific proteins and identify putative receptors, we have developed a comprehensive comparative analysis of the proteomes of four cuticular anatomical structures of the pea aphid, stylets, antennae, legs, and wings. In addition, we performed systematic immunolabeling detection of the cuticular proteins identified by mass spectrometry in dissected stylets. We thereby establish the first proteome of stylets of an insect and determine the minimal repertoire of the cuticular proteins composing the acrostyle. Most importantly, we propose a short list of plant virus receptor candidates, among which RR-1 proteins are remarkably predominant. The data are available via ProteomeXchange (PXD016517).

Modelling and manipulation of aphid-mediated spread of non-persistently transmitted viruses

Aphids vector many plant viruses in a non-persistent manner i.e., virus particles bind loosely to the insect mouthparts (stylet). This means that acquisition of virus particles from infected plants, and inoculation of uninfected plants by viruliferous aphids, are rapid processes that require only brief probes of the plant's epidermal cells. Virus infection alters plant biochemistry, which causes changes in emission of volatile organic compounds and altered accumulation of nutrients and defence compounds in host tissues. These virus-induced biochemical changes can influence the migration, settling and feeding behaviours of aphids. Working mainly with cucumber mosaic virus and several potyviruses, a number of research groups have noted that in some plants, virus infection engenders resistance to aphid settling (sometimes accompanied by emission of deceptively attractive volatiles, that can lead to exploratory penetration by aphids without settling). However, in certain other hosts, virus infection renders plants more susceptible to aphid colonisation. It has been suggested that induction of resistance to aphid settling encourages transmission of non-persistently transmitted viruses, while induction of susceptibility to settling retards transmission. However, recent mathematical modelling indicates that both virus-induced effects contribute to epidemic development at different scales. We have also investigated at the molecular level the processes leading to induction, by cucumber mosaic virus, of feeding deterrence versus susceptibility to aphid infestation. Both processes involve complex interactions between specific viral proteins and host factors, resulting in manipulation or suppression of the plant's immune networks.

Molecular dynamics investigations for the prediction of molecular interaction of cauliflower mosaic virus transmission helper component protein complex with Myzus persicae stylet's cuticular protein and its docking studies with annosquamosin-A encapsulated in nano-porous Silica

Large numbers of bioactive natural products from plant species such as alkaloids, phenolics, terpenoids etc. are remaining unexplored for their potential as plant protective agents as inhibitors for viral and other pathogenic infections of plant. Myzus aphids are important plant pests and vectors for several plant viruses. Cauliflower mosaic virus (CaMV) belongs to the plant virus family Caulimoviridae which is transmitted "non-circulative" from plant to plant through an interaction with aphid insect vectors. This viral transmission process most likely involves a protein-protein binding interaction between aphid stylet receptor cuticular protein and viral proteins namely, CaMV aphid transmission Helper Component protein and virion associated protein. Aphid stylets are made of cuticle and little is known about the structure of cuticle protein of this insect group. The present study reports the molecular modeling of the structures of Myzus persicae aphid stylet's cuticular protein (MpsCP) and cauliflower mosaic virus aphid transmission Helper component protein (CaMV HCP). Protein-protein docking studies and molecular dynamics simulations are performed to establish the mode of binding of MpsCP with CaMV HCP. Molecular docking and molecular dynamics investigations of terpenoids Annosquamosin-A from Annona squamosa complex with CaMV transmitting aphid M. persicae stylet's cuticular protein revealed their means of interaction perhaps relates to restrain viral binding and transmission. QM/MM optimization of mesoporous silica nanopores composite with Annosquamosin-A for smart and safe delivery of bioactive is carried out to study their electronic parameters such as heat of formation, total energy, electronic energy, Ionization potential, Highest Occupied Molecular Orbital, Lowest Un-occupied Molecular Orbital and energy gaps.

Differences in gene expression in whitefly associated with CYSDV-infected and virus-free melon, and comparison with expression in whiteflies fed on ToCV- and TYLCV-infected tomato

Background

Cucurbit yellow stunting disorder virus (CYSDV; genus Crinivirus, Closteroviridae) is transmitted in a semipersistent manner by the whitefly, Bemisia tabaci, and is efficiently transmitted by the widely prevalent B. tabaci cryptic species, MEAM1. In this study, we compared transcriptome profiles of B. tabaci MEAM1, after 24 h, 72 h and 7 days of acquisition feeding on melon plants infected with CYSDV (CYSDV-whiteflies) with those fed on virus-free melon, using RNA-Seq technology. We also compared transcriptome profiles with whiteflies fed on tomato plants separately infected with Tomato chlorosis virus (ToCV), a crinivirus closely related to CYSDV, and Tomato yellow leaf curl virus (TYLCV), a member of the genus Begomovirus, which has a distinctly different mode of transmission and their respective virus-free controls, to find common gene expression changes among viruliferous whiteflies feeding on different host plants infected with distinct (TYLCV) and related (CYSDV and ToCV) viruses.

Results

A total of 275 differentially expressed genes (DEGs) were identified in CYSDV-whiteflies, with 3 DEGs at 24 h, 221 DEGs at 72 h, and 51 DEGs at 7 days of virus acquisition. Changes in genes encoding orphan genes (54 genes), phosphatidylethanolamine-binding proteins (PEBP) (20 genes), and AAA-ATPase domain containing proteins (10 genes) were associated with the 72 h time point. Several more orphan genes (20 genes) were differentially expressed at 7 days. A total of 59 common DEGs were found between CYSDV-whiteflies and ToCV-whiteflies, which included 20 orphan genes and 6 lysosomal genes. A comparison of DEGs across the three different virus-host systems revealed 14 common DEGs, among which, eight showed similar and significant up-regulation in CYSDV-whiteflies at 72 h and TYLCV-whiteflies at 24 h, while down-regulation of the same genes was observed in ToCV-whiteflies at 72 h.

Conclusions

Dynamic gene expression changes occurred in CYSDV-whiteflies after 72 h feeding, with decreased gene expression changes associated with 7 days of CYSDV acquisition. Similarities in gene expression changes among CYSDV-whiteflies, ToCV-whiteflies and TYLCV-whiteflies suggest the possible involvement of common genes or pathways for virus acquisition and transmission by whiteflies, even for viruses with distinctly different modes of transmission.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5999-0) contains supplementary material, which is available to authorized users.

The vitellogenin receptor has an essential role in vertical transmission of rice stripe virus during oogenesis in the small brown plant hopper

BACKGROUND

The small brown plant hopper (SBPH), Laodelphax striatellus Fallén, is one of the most destructive pests on rice. This pest transmits rice stripe virus (RSV) both horizontally and vertically, leading to major yield and economic losses in rice production. However, the way that RSV particles enter oocytes of SBPH remains largely unknown. Thus, identification of key factors involved in the interaction between SBPH and RSV in the ovary is crucial.

RESULTS

Transcriptome of non-viruliferous (NV) or high viruliferous (HV) SBPH ovaries at 24 and 48 h of emergence was sequenced. Differentially expressed genes analysis showed that vitellogenin receptor was significantly highly expressed in the ovary of the HV SBPH strains compared to NV strains. Quantitative real-time polymer chain reaction showed that the vitellogenin receptor in L. striatellus (LsVgR) was highly expressed in the ovaries of female adults and maintained a high level of expression at the early stage of ovary development. By using RNA interference, the expression of LsVgR in the ovaries of the HV strain was significantly decreased by 98.1%. RSV titer was reduced by 60.9% as quantified by viral RNA3 intergenic region and the transcripts of nucleocapsid protein gene (CP) reduced by 46.3%. The numbers of offspring hatched were significantly reduced in dsRNA-treated groups. The transcripts of CP were not affected by silencing LsVgR, whereas the abundance of RNA-dependent RNA polymerase increased by 15-fold in the member of surviving progenies.

CONCLUSION

Our results suggest that vitellogenin receptor participates in regulating RSV replication during oogenesis. © 2018 Society of Chemical Industry.

An Approach to Identify New Insecticides Against Myzus Persicae. In silico Study Based on Linear and Non-linear Regression Techniques

Neonicotinoids are known to have high insecticidal potency, low mammalian toxicity and relatively tough activity for the development of resistance against aphids. A series of guadipyr insecticides, active against Myzus persicae was engaged in silico studies, based on Multiple Linear Regression (MLR), Partial Least Squares regression (PLS), Artificial Neural Networks (ANN), Support Vector Machine (SVM) and Pharmacophore modeling. Robust and predictive models were built using correlations between the insecticidal profile, expressed by experimental pLC₅₀ values, and molecular descriptors, calculated from the energy optimized structures. Four new potential insecticides active against Myzus persicae and their predicted pLC₅₀ toxicity values were reported for the first time. The models presented here can be used as an approach in the screening and prioritization of chemicals in a scientific and regulatory frame and for toxicity prediction.

Molecular Modeling for Better Understanding of Cucumovirus Pathology

Cucumber mosaic virus (CMV) is a small RNA virus capable of infecting a wide variety of plant species. The high economic losses due to the CMV infection made this virus a relevant subject of scientific studies, which were further facilitated by the small size of the viral genome. Hence, CMV also became a model organism to investigate the molecular mechanism of pathogenesis. All viral functions are dependent on intra- and intermolecular interactions between nucleic acids and proteins of the virus and the host. This review summarizes the recent data on molecular determinants of such interactions. A particular emphasis is given to the results obtained by utilizing molecular-based planning and modeling techniques.

Insect cuticular proteins and their role in transmission of phytoviruses

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Cuticular proteins play key roles in plant virus transmission.

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RR-1 and RR-2 are the main cuticular proteins involved in virus–vector interactions.

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RR-1 protein is involved in transmission of a noncirculative virus.

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RR-1 protein is involved in transmission of a circulative virus.

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The role of other cuticular proteins in virus transmission is poorly characterized.

Many viruses of agricultural importance are transmitted to host plants via insect vectors. Characterizing virus–vector interactions at the molecular level is essential if we are to fully understand the transmission mechanisms involved and develop new strategies to control viral spread. Hitherto, insect proteins involved in virus transmission have been characterized only poorly. Recent advances in this topic, however, have significantly filled this knowledge gap. Among the vector molecules identified, cuticular proteins have emerged as key molecules for plant virus transmission, regardless of transmission mode or vector considered. Here, we review recent evidence highlighting that the CPR family, and particularly RR-1 proteins, undoubtedly deserves special attention.

Identification of Plant Virus Receptor Candidates in the Stylets of Their Aphid Vectors

Plant viruses transmitted by insects cause tremendous losses in most important crops around the world. The identification of receptors of plant viruses within their insect vectors is a key challenge to understanding the mechanisms of transmission and offers an avenue for future alternative control strategies to limit viral spread. We here report the identification of two cuticular proteins within aphid mouthparts, and we provide experimental support for the role of one of them in the transmission of a noncirculative virus. These two proteins, named Stylin-01 and Stylin-02, belong to the RR-1 cuticular protein subfamily and are highly conserved among aphid species. Using an immunolabeling approach, they were localized in the maxillary stylets of the pea aphid Acyrthosiphon pisum and the green peach aphid Myzus persicae, in the acrostyle, an organ earlier shown to harbor receptors of a noncirculative virus. A peptide motif present at the C termini of both Stylin-01 and Stylin-02 is readily accessible all over the surface of the acrostyle. Competition for in vitro binding to the acrostyle was observed between an antibody targeting this peptide and the helper component protein P2 of Cauliflower mosaic virus Furthermore, silencing the stylin-01 but not stylin-02 gene through RNA interference decreased the efficiency of Cauliflower mosaic virus transmission by Myzus persicae These results identify the first cuticular proteins ever reported within arthropod mouthparts and distinguish Stylin-01 as the best candidate receptor for the aphid transmission of noncirculative plant viruses.IMPORTANCE Most noncirculative plant viruses transmitted by insect vectors bind to their mouthparts. They are acquired and inoculated within seconds when insects hop from plant to plant. The receptors involved remain totally elusive due to a long-standing technical bottleneck in working with insect cuticle. Here we characterize the role of the two first cuticular proteins ever identified in arthropod mouthparts. A domain of these proteins is directly accessible at the surface of the cuticle of the acrostyle, an organ at the tip of aphid stylets. The acrostyle has been shown to bind a plant virus, and we consistently demonstrated that one of the identified proteins is involved in viral transmission. Our findings provide an approach to identify proteins in insect mouthparts and point at an unprecedented gene candidate for a plant virus receptor.