ABSTRACT: Global analysis of the transcriptional difference between indigenous and invasive whiteflies reveals the possible mechanism of whitefly invasion
Project description:The whitefly Bemisa tabaci is a species complex of more than 31 cryptic species which include some of the most destructive invasive pests of many ornamental and glasshouse crops worldwide. Among them, Middle East-Asia Minor 1 (herein MEAM1) and Mediterranean (herein MED) have invaded many countries around the world and displaced the native whitefly species. However, the molecular differences between invasive and indigenous whiteflies remain largely unknown. The global transcriptional difference between the two invasive whitefly Bemisia tabaci species (MEAM1, MED) and one indigenous whitefly species (Asia II 3) were analyzed using the Illumina sequencing technology.
Project description:The whitefly, Bemisia tabaci MEAM1 is a devastating vector capable of transmitting hundreds of plant viruses, including Tomato yellow leaf curl virus (TYLCV), to important food and fiber crops. Here we performed genome-wide profiling of micro RNAs (miRNAs) and piwi-interacting RNAs (piRNAs) in whiteflies after feeding on TYLCV-infected tomato or uninfected tomato for 24, 48 and 72 h. Overall, 160 miRNAs were discovered, 68 of which were conserved and 92 were B. tabaci-specific miRNAs. Majority of the genes that were predicted to be targeted by miRNAs had gene ontologies related to metabolic processes. We identified two miRNAs that were differentially expressed in whiteflies when fed on TYLCV-infected tomato compared to whiteflies that fed on uninfected tomato. The identified piRNAs were expressed as clusters throughout the whitefly genome. A total of 53 piRNA clusters were expressed across all time points and treatments, while 5 piRNA clusters were exclusively expressed in whiteflies that fed on TYLCV-infected tomato, and 24 clusters were exclusively expressed in whiteflies that fed on uninfected tomato. Approximately 62% of all identified piRNAs were derived from non-coding sequences that included intergenic regions, introns, and UTRs with unknown functions. The remaining 38% of piRNAs were derived from coding sequences (CDS) and repeat elements. Transposable elements targeted by piRNA clusters included both class I retrotransposons such as Gypsy, Copia, and LINEs and class II DNA transposons such as MITE, hAT, and TcMar. Lastly, six protein coding genes were targeted in whiteflies that fed on TYLCV-infected tomato. Information on how TYLCV influences miRNA and piRNA expression in whiteflies provides a greater understanding of regulatory pathways involved in mediating whitefly-virus interactions, and will facilitate the identification of novel targets for RNAi control.
Project description:The whitefly Bemisa tabaci is a species complex of more than 31 cryptic species which include some of the most destructive invasive pests of many ornamental and glasshouse crops worldwide. Among them, Middle East-Asia Minor 1 (herein MEAM1) and Mediterranean (herein MED) have invaded many countries around the world and displaced the native whitefly species. However, the molecular differences between invasive and indigenous whiteflies remain largely unknown.
Project description:The whitefly, Bemisia tabaci, a notorious agricultural pest, has complex relationships with diverse microbes. It recognizes and degrades pathogens, as other insects do, and also relies on endosymbionts for its survival. Both types of interaction have received great attention, because of their potential importance in developing novel whitefly control technologies. The recent developments in RNA-seq technology allows us to perform a comprehensive investigation of a whitefly’s defense responses after it has ingested the pathogen, Pseudomonas aeruginosa. Compared to uninfected whiteflies, 6 and 24 hour post-infected (hpi) whiteflies showed 1,348 and 1,888 differentially expressed genes, respectively. Functional analysis highlighted the involvement of mitogen associated protein kinase (MAPK) pathway in host-defense regulation. Three knottin-like antimicrobial peptide genes and several components of the humoral and cellular immune response were also activated, indicating that key immune elements recognized in other insect species are also important for the host response of B. tabaci. Our data also suggest that intestinal stem cell mediated epithelium renewal might be an important component of the whitefly’s defense against oral bacterial infection. In addition, we also show stress responses to be an essential component of the defense system. We identify for the first time the key immune-response elements utilized by B. tabaci against bacterial infection. This provides a framework for future research into the complex interactions between whiteflies and microbes.
Project description:Transcriptional responses of an indigenous and an invasive whitefly to different host plants reveal their different capacity of adaptation
Project description:The whitefly Bemisia tabaci (Gennadius) causes tremendous losses to agriculture by direct feeding on plants and by vectoring several families of plant viruses. The B. tabaci species complex comprises over 10 genetic groups (biotypes) that are well defined by DNA markers and biological characteristics. B and Q are amongst the most dominant and damaging biotypes, differing considerably in fecundity, host range, insecticide resistance, virus vectoriality, and the symbiotic bacteria they harbor. We used a spotted B. tabaci cDNA microarray to compare the expression patterns of 6,000 ESTs of B and Q biotypes under standard 25°C regime and heat stress at 40°C. Overall, the number of genes affected by increasing temperature in the two biotypes was similar. Gene expression under 25ºC normal rearing temperature showed clear differences between the two biotypes: B exhibited higher expression of mitochondrial genes, and lower cytoskeleton, heat-shock and stress-related genes, compared to Q. Exposing B-biotype whiteflies to heat stress was accompanied by rapid alteration of gene expression. For the first time, the results here present differences in gene expression between very closely related and sympatric B. tabaci biotypes, and suggest that these clear-cut differences are due to better adaptation of one biotype over another and might eventually lead to changes in the local and global distribution of both biotypes.
Project description:The whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), and the viruses it transmits, are a major constraint to vegetable crops, worldwide. Although the whitefly is usually controlled using chemical pesticides, biological control agents constitute an important component in integrated pest management programs. One of these agents is the wasp Eretmocerus mundus (Mercet) (Hymenoptera: Aphelinidae). E. mundus lays its egg on the leaf underneath the pupa of B. tabaci. First instars of the wasp hatch and penetrate the whitefly larvae. Initiation of parasitization induces the host to form a cellular capsule around the parasitoid. Around this capsule, epidermal cells multiply and thick layers of cuticle are deposited. The physiological and molecular processes underlying B. tabaci-E. mundus interactions have not been investigated so far. We have used a cDNA microarray containing 6,000 expressed sequence tags (ESTs) from the whitefly genome to study the parasitoid-whitefly interaction. We compared RNA samples collected across two time points of the parasitization process: when the parasitoid first instar started the penetration process and once it had fully penetrated the host. The results clearly indicated that genes known to be part of the defense pathways described in other insects are also involved in the response of B. tabaci to parasitization by E. mundus. Some of the responses observed included the repression of a serine protease inhibitor (serpin) and the induction of a melanization cascade. A second set of genes that strongly responded to parasitization included bacterial genes encoded by whitefly symbionts. Quantitative real-time PCR and FISH analyses showed that proliferation of Rickettsia, a facultative secondary symbiont, was strongly induced following the initiation of the parasitization process, a result that supported previous reports suggesting that endosymbionts may be involved in the insect host resistance to various environmental stresses. This is the first study examining the transcriptional response of a hemipteran insect to the attack of a biological control agent (Hymenopterous parasitoid), using a new genomic approach developed for this insect pest. The defense response in B. tabaci seems to resemble that of model organisms such as Drosophila melanogaster. Moreover, endosymbionts of B. tabaci seem to play a role in the response to parasitization, and this is supported by previously published results from aphids. Keywords: time course
Project description:The whitefly Bemisia tabaci (Gennadius) causes tremendous losses to agriculture by direct feeding on plants and by vectoring several families of plant viruses. The B. tabaci species complex comprises over 10 genetic groups (biotypes) that are well defined by DNA markers and biological characteristics. B and Q are amongst the most dominant and damaging biotypes, differing considerably in fecundity, host range, insecticide resistance, virus vectoriality, and the symbiotic bacteria they harbor. We used a spotted B. tabaci cDNA microarray to compare the expression patterns of 6,000 ESTs of B and Q biotypes under standard 25°C regime and heat stress at 40°C. Overall, the number of genes affected by increasing temperature in the two biotypes was similar. Gene expression under 25ºC normal rearing temperature showed clear differences between the two biotypes: B exhibited higher expression of mitochondrial genes, and lower cytoskeleton, heat-shock and stress-related genes, compared to Q. Exposing B-biotype whiteflies to heat stress was accompanied by rapid alteration of gene expression. For the first time, the results here present differences in gene expression between very closely related and sympatric B. tabaci biotypes, and suggest that these clear-cut differences are due to better adaptation of one biotype over another and might eventually lead to changes in the local and global distribution of both biotypes. 3 replicates comparing Q biotype under 40 degrees celsius (C) with three replicates under 25 C. The same number of replicates comparing B biotype under 40 C and 25 C, and three replicates comparing B and Q biotypes under 25 C.
Project description:Tomato seeds (S. lycopersicum ‘Fl Lanai’) were germinated under greenhouse conditions maintained at 24°C-29°C in flat trays (BWI Apopka, Catalog Number GPPF72S7X) filled with Sungro Horticulture soil (Metro-mix 830, BWI Apopka, Cat# TX830). Two weeks post emergence seedlings were transplanted to 4” pots using the same soil and transferred to a Conviron walk-in growth chamber (CMP6060) for the remainder of the experiment. Conviron conditions include a 14h/10h light/dark cycle maintained at 28°C, and plants were fertilized weekly (20-20-20). To prevent cross contamination, tomato plants were confined to insect proof cages at all times (BioQuip 1450NS68). Four weeks after transplanting, 40 whiteflies (B. tabaci MEAM1) were collected from virus free or Tomato Mottle Virus (ToMoV) established colonies via aspiration and moved into a clip cage placed on the 4th true leaf of each tomato plant as previously described38. Whiteflies were reared cabbage (Brassica oleracea), while viruliferous whiteflies were reared on ToMoV infected tomato from colonies established in the Polston lab. For all plants in this study, feeding was halted after 3 days of whitefly feeding (3 DPI) by gentle removal of clip cages and whitefly termination using insecticidal soap (Garden Safe, 1% of potassium salts of fatty acids). For the samples referred to as “local”, the tomato leaf bound within the clip cages was immediately removed and snap frozen for protein extraction. For the samples designated “systemic”, the plants were allowed to continue growing for 7 additional days after clip cage removal and whitefly termination, at which point the 9th leaf was excised and snap frozen. Plants used for collection of local leaves at 3 DPI were not used for the collection of systemic leaves 10 DPI. For both local and systemic leaves collected, we also included a no treatment control (NTC) that was subjected identically to clip cage and insecticidal soap applications, but without the addition of whitefly or ToMoV. Our experiment therefore consists of a no-treatment control (NTC), a whitefly treatment (+WF), and a viruliferous whitefly (+WFV) treatment for both local (4th true leaf, 3 DPI) and systemic leaves (9th true leaf, 10 DPI). The presence of ToMoV in all infected plants was confirmed via Nanopore sequencing. Briefly, Tomato genomic DNA was extracted from five systemic leaf samples using the PureGene tissue DNA isolation kit (product # 158667; QIAGEN, Valencia, CA, USA), following the manufacturer’s protocol and stored at -80°C until needed. Library preparation was performed using the Rapid Sequencing Kit RBK004 protocol (Oxford Nanopore Technologies) and loaded onto a 9.4.1 flow cell in a MinION connected to a MinIT with live base calling enabled. Resulting sequencing reads for each sample were mapped to both ToMoV A component (GenBank accession: L14460) and ToMoV B component (GenBank accession: L14461) sequences.
Project description:The whitefly Bemisa tabaci is a species complex with global distribution and extensive genetic diversity. In this species complex, Middle East-Asia Minor 1 (MEAM1, previously referred to as the âB biotypeâ) species has been spreading rapidly in tropical and subtropical regions. we analyzed the transcriptional responses of the invasive MEAM1 and the indigenous Asia II 3 species of B. tabaci complex during host plant shift (from cotton to tobacco) using the Illumina sequencing technology.The different gene expression pattern of energy and carbonhydrate metabolism and detoxification metabolism between MEAM1 and Asia II 3 were the main reasons of their different capacity of adapation. The global transcriptional difference between the invasive whitefly Bemisia tabaci species (MEAM1) and the indigenous whitefly species (Asia II 3) on cotton and tobacco were analyzed using the Illumina sequencing technology.