Two Deoxythymidine Triphosphate Synthesis-Related Genes Regulate Obligate Symbiont Density and Reproduction in the Whitefly Bemisia tabaci MED.
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ABSTRACT:
SUBMITTER: Yang Z
PROVIDER: S-EPMC7943623 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundBacterial symbiosis is widespread in arthropods, especially in insects. Some of the symbionts undergo a long-term co-evolution with the host, resulting in massive genome decay. One particular consequence of genome decay is thought to be the elimination of transcriptional elements within both the coding region and intergenic sequences. In the whitefly Bemisia tabaci species complex, the obligate symbiont Candidatus Portiera aleyrodidarum is of vital importance in nutrient provision, and yet little is known about the regulatory capacities of it.MethodsPortiera genomes of two whitefly species in China were sequenced and assembled. Gene content of these two Portiera genomes was predicted, and then subjected to Kyoto Encyclopedia of Genes and Genomes pathway analysis. Together with two other Portiera genomes from whitefly species available previously, four Portiera genomes were utilized to investigate regulatory capacities of Portiera, focusing on transcriptional elements, including genes related with transcription and functional elements within the intergenic spacers.ResultsComparative analyses of the four Portiera genomes of whitefly B. tabaci indicate that the obligate symbionts Portiera is similar in different species of whiteflies, in terms of general genome features and possible functions in the biosynthesis of essential amino acids. The screening of transcriptional factors suggests compromised ability of Portiera to regulate the essential amino acid biosynthesis pathways. Meanwhile, thermal tolerance ability of Portiera is indicated with the detection of a σ32 factor, as well as two predicted σ32 binding sites. Within intergenic spacers, functional elements are predicted, including 37 Shine-Dalgarno sequences and 34 putative small RNAs.
| S-EPMC6699477 | biostudies-literature
Project description:The sweetpotato whitefly Bemisia tabaci is a highly destructive agricultural and ornamental crop pest. It damages host plants through both phloem feeding and vectoring plant pathogens. Introductions of B. tabaci are difficult to quarantine and eradicate because of its high reproductive rates, broad host plant range, and insecticide resistance. A total of 791 Gb of raw DNA sequence from whole genome shotgun sequencing, and 13 BAC pooling libraries were generated by Illumina sequencing using different combinations of mate-pair and pair-end libraries. Assembly gave a final genome with a scaffold N50 of 437 kb, and a total length of 658 Mb. Annotation of repetitive elements and coding regions resulted in 265.0 Mb TEs (40.3%) and 20 786 protein-coding genes with putative gene family expansions, respectively. Phylogenetic analysis based on orthologs across 14 arthropod taxa suggested that MED/Q is clustered into a hemipteran clade containing A. pisum and is a sister lineage to a clade containing both R. prolixus and N. lugens. Genome completeness, as estimated using the CEGMA and Benchmarking Universal Single-Copy Orthologs pipelines, reached 96% and 79%. These MED/Q genomic resources lay a foundation for future 'pan-genomic' comparisons of invasive vs. noninvasive, invasive vs. invasive, and native vs. exotic Bemisia, which, in return, will open up new avenues of investigation into whitefly biology, evolution, and management.
| S-EPMC5467035 | biostudies-literature
Project description:The whitefly Bemisia tabaci is a phloem-feeding pest that lives predominantly on herbaceous species and causes serious damage to hosts. Whitefly saliva is thought to contain proteins that modulate plant defences and facilitate feeding. A predicted secreted protein, laccase 1 (LAC1), was found in the salivary gland transcriptome of B. tabaci and might be existed in the watery saliva of B. tabaci. As LAC1 has a potential role in detoxification of secondary plant compounds in insects, we speculated that it may participate in the insect's response to plant defences. Here, we cloned the complete cDNA of LAC1 and found that (1) LAC1 was highly expressed in the salivary gland (SG) and midgut; (2) LAC1 transcript level in head (containing SG) was 2.1 times higher in plant-fed than in diet-fed whiteflies and 1.6 times higher in the head and 23.8 times higher in the midgut of whiteflies that fed on jasmonic acid (JA)-sprayed plants than on control plants; and (3) silencing LAC1 decreased the survival rate of plant-fed whiteflies but had a marginal effect on whiteflies raised on an artificial diet. These results indicate that LAC1 enables whiteflies to overcome the chemical defences of host plants and might act as an effector in saliva.
| S-EPMC5472608 | biostudies-literature
Project description:Bemisia tabaci (Hemiptera: Aleyrodidae) is a species complex containing >28 cryptic species, some of which are important crop pests worldwide. Like many other sap-sucking insects, whiteflies harbor an obligatory symbiont, "Candidatus Portiera aleyrodidarum," and a number of secondary symbionts. So far, six genera of secondary symbionts have been identified in B. tabaci. In this study, we report and describe the finding of an additional bacterium in the indigenous B. tabaci cryptic species China 1 (formerly known as B. tabaci biotype ZHJ3). Phylogenetic analysis based on the 16S rRNA and gltA genes showed that the bacterium belongs to the Alphaproteobacteria subdivision of the Proteobacteria and has a close relationship with human pathogens of the genus Orientia. Consequently, we temporarily named it Orientia-like organism (OLO). OLO was found in six of eight wild populations of B. tabaci China 1, with the infection rate ranging from 46.2% to 76.8%. Fluorescence in situ hybridization (FISH) of B. tabaci China 1 in nymphs and adults revealed that OLOs are confined to the bacteriome and co-occur with "Ca. Portiera aleyrodidarum." The vertical transmission of OLO was demonstrated by detection of OLO at the anterior pole end of the oocytes through FISH. Quantitative PCR analysis of population dynamics suggested a complex interaction between "Ca. Portiera aleyrodidarum" and OLO. Based on these results, we propose "Candidatus Hemipteriphilus asiaticus" for the classification of this symbiont from B. tabaci.
| S-EPMC3553764 | biostudies-literature
Project description:BackgroundRNA interference has been emerged as an utmost tool for the control of sap sucking insect pests. Systemic response is necessary to control them in field condition. Whitefly is observed to be more prone to siRNA in recent studies, however the siRNA machinery and mechanism is not well established.Methodology/principal findingsTo identify the core siRNA machinery, we curated transcriptome data of whitefly from NCBI database. Partial mRNA sequences encoding Dicer2, R2D2, Argonaute2 and Sid1 were identified by tblastn search of homologous sequences from Aphis glycines and Tribolium castaneum. Complete encoding sequences were obtained by RACE, protein sequences derived by Expasy translate tool and confirmed by blastp analysis. Conserved domain search and Prosite-Scan showed similar domain architecture as reported in homologs from related insects. We found helicase, PAZ, RNaseIIIa, RNaseIIIb and double-stranded RNA-binding fold (DSRBF) in Dicer2; DsRBD in R2D2; and PAZ and PIWI domains in Argonaute2. Eleven transmembrane domains were detected in Sid1. Sequence homology and phylogenetic analysis revealed that RNAi machinery of whitefly is close to Aphids. Real-time PCR analysis showed similar expression of these genes in different developmental stages as reported in A. glycines and T. castaneum. Further, the expression level of above genes was quite similar to the housekeeping gene actin.Conclusions/significanceAvailability of core siRNA machinery including the Sid1 and their universal expression in reasonable quantity indicated significant response of whitefly towards siRNA. Present report opens the way for controlling whitefly, one of the most destructive crop insect pest.
| S-EPMC3877088 | biostudies-literature
Project description:Over the past decade RNA interference (RNAi) technology has emerged as a successful tool not only for functional genomics, but in planta expression of short interfering RNAs (siRNAs) that could offer great potential for insect pest management. The diet of insects feeding exclusively on phloem sieves contains water and sugars as main components, and the uptake of the liquid food greatly depends on the osmotic pressure within the insect body. Based on this physiological mechanism, transgenic plants of Nicotiana tabacum were generated expressing double stranded RNA (dsRNA) against both aquaporin (AQP) and a sucrase gene, alpha glucosidase (AGLU). These two genes are involved in osmotic pressure maintenance particularly in sap sucking insects, and the aim was to disrupt osmoregulation within the insect ultimately leading to mortality. Real time quantitative PCR (RT-qPCR) was performed to assess the suppression of gene expression in Bemisia tabaci (B. tabaci) and mortality was recorded during transgenic tobacco feeding bioassays. Feeding of insects on plants expressing dsRNA significantly reduced the transcript level of the target genes in B. tabaci after six days of feeding and more than 70% mortality was observed in B. tabaci fed on transgenic plants compared to the control plants. Our data shows that down-regulation of genes related to osmoregulation may find practical applications for the control of this important pest in cotton and other crops.
| S-EPMC4841547 | biostudies-literature
Project description:The whitefly, Bemisia tabaci (Gennadius) cryptic species Mediterranean (MED), is a destructive insect pest worldwide. In order to contribute to controlling B. tabaci by non-chemical methods, we examined the possibility of using a combination of trap/barrier crops and a parasitoid natural enemy in cotton. We performed field experiments using cantaloupe (Cucumis melo) and sunflower (Helianthus annuus) as trap crops and maize (Zea mays) as a barrier crop combined with periodic releases of the parasitoid Eretmocerus hayati in Hebei Province, Northern China. All treatments significantly reduced immature whitefly densities. Parasitism rate was significantly higher in cotton plots intercropped with sunflower and with perimeter-planted cantaloupe. Adult whitefly density was negatively related to parasitoid abundance and was significantly lower in cotton plots intercropped with maize than in the control plots. Intercropping was more effective than perimeter-planting at reducing B. tabaci densities and increasing yield. Parasitoid dispersal was not hampered by barrier crops, indicating that the two methods of control are compatible. These results contribute to the development of integrated pest management methods against this important pest.
| S-EPMC7022622 | biostudies-literature
Project description:Bemisia tabaci whitefly species are some of the world's most devastating agricultural pests and plant-virus disease vectors. Elucidation of the phylogenetic relationships in the group is the basis for understanding their evolution, biogeography, gene-functions and development of novel control technologies. We report here the discovery of five new Sub-Saharan Africa (SSA) B. tabaci putative species, using the partial mitochondrial cytochrome oxidase 1 gene: SSA9, SSA10, SSA11, SSA12 and SSA13. Two of them, SSA10 and SSA11 clustered with the New World species and shared 84.8‒86.5% sequence identities. SSA10 and SSA11 provide new evidence for a close evolutionary link between the Old and New World species. Re-analysis of the evolutionary history of B. tabaci species group indicates that the new African species (SSA10 and SSA11) diverged from the New World clade c. 25 million years ago. The new putative species enable us to: (i) re-evaluate current models of B. tabaci evolution, (ii) recognise increased diversity within this cryptic species group and (iii) re-estimate divergence dates in evolutionary time.
| S-EPMC5807539 | biostudies-literature
Project description:Mating triggers substantial changes in gene expression and leads to subsequent physiological and behavioral modifications. However, postmating transcriptomic changes responding to mating have not yet been fully understood. Here, we carried out RNA sequencing (RNAseq) analysis in the sweet potato whitefly, Bemisia tabaci MED, to identify genes in females in response to mating. We compared mRNA expression in virgin and mated females at 24 h. As a result, 434 differentially expressed gene transcripts (DEGs) were identified between the mated and unmated groups, including 331 up- and 103 down-regulated. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed that many of these DEGs encode binding-related proteins and genes associated with longevity. An RT-qPCR validation study was consistent with our transcriptomic analysis (14/15). Specifically, expression of P450s (Cyp18a1 and Cyp4g68), ubiquitin-protein ligases (UBR5 and RNF123), Hsps (Hsp68 and Hsf), carboxylase (ACC-2), facilitated trehalose transporters (Tret1-2), transcription factor (phtf), and serine-protein kinase (TLK2) were significantly elevated in mated females throughout seven assay days. These combined results offer a glimpe of postmating molecular modifications to facilitate reproduction in B. tabaci females.
| S-EPMC7290661 | biostudies-literature
Project description:The Bemisia tabaci (Gennadius) cryptic species complex includes important crop pests, and among them, the cryptic species Mediterranean (MED) and Middle East-Asia Minor 1 (MEAM1) cause substantial crop losses in China. The second-generation neonicotinoid clothianidin acts as an agonist of the nicotinic acetylcholine receptor in the insect nervous system and has both stomach and contact activity. In this study, the toxicity of clothianidin and five other insecticides to MED and MEAM1 was examined. The sublethal effects of clothianidin on the development and reproduction of MED and MEAM1 were also investigated. Among the six insecticides tested, clothianidin showed toxicities to both MED and MEAM1 adults with LC50 values of 5.23 and 5.18 mg/liter, respectively. The sublethal effects of clothianidin were assessed by treating MED and MEAM1 adults with the LC25 of 1.58 and 1.13 mg/liter, respectively. The LC25 treatments accelerated the development of the F1 generation but reduced survival and fecundity of both species. Our results indicate that clothianidin could be useful for the management of B. tabaci MED and MEAM1.
| S-EPMC5887484 | biostudies-literature