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) 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:The whitefly Bemisia tabaci is a notorious pest of worldwide agriculture. It is believed to secrete saliva to counter plant defenses, but the underlying mechanism remains to be elucidated. Here, we characterize the gene/protein repertoires of B. tabaci salivary glands and secreted saliva by transcriptomic and LC–MS/MS analysis. A total of 698 salivary gland-higher expressed unigenes, as well as 172 saliva proteins are identified. Comparative analysis of the saliva composition in different arthropod species illustrates that proteins associated with binding, hydrolysis and oxidation-reduction are widely distributed in herbivorous saliva. There are 74 saliva proteins exclusively identified in B. tabaci, with 34 of them being B. tabaci-specific. In addition, eleven B. tabaci-specific saliva proteins plastically regulated in response to different diets, which might be associated with wide host range of this pest. Our results gain insight into whitefly–plant interactions, and provide a good resource for functional characterization of effectors
Project description:To investigated the stage-specific gene expression response to thiamethoxam in the Bemisia tabaci, we have designed the Agilent eArray platform to identify stage-regulated gene expression towards thiamethoxam exposure.
Project description:Background: The whitefly Bemisia tabaci is a major generalist agricultural pest of field and horticultural crops world-wide. Despite its importance, the molecular bases of defense mechanisms in B. tabaci against major plant secondary defense compounds, such as the phenylpropanoids, remain unknown. Results: Our experimental system utilized transgenic Nicotiana tabacum plants constitutively expressing the PAP1 M-bM-^AM-^D AtMYB75 transcription factor which activates specifically the phenylpropanoid / flavonoids biosynthetic pathway. Our study used suppression subtractive hybridization (SSH) and cDNA microarray approaches to compare gene expression between B. tabaci adults subjected to wild-type or transgenic plants for six hours. A total of 2880 clones from the SSH libraries were sequenced. Both the SSH and cDNA microarray analyses indicated a complex interaction between B. tabaci and secondary defense metabolites produced by the phenylproapnoids / flavonoids pathway, involving enhanced expression of detoxification, immunity, oxidative stress and general stress related genes as well as general metabolism and ribosomal genes. Quantitative PCR revealed significant changes in the expression of several of these genes in response to feeding on artificial diet containing the flavonol quercetin. The elevated transcriptional activity was not accompanied by reduced reproductive performance, indicating high adaptability of B. tabaci to this large group of plant secondary defense metabolites. Conclusion: Results of this study allows first insight into the molecular mechanisms underlining polyphagy in B. tabaci. Our analyses revealed many candidate genes related to the insect's various defense systems capable of neutralizing a broad range of plant toxins. Future technological developments allowing silencing or over-expression of selected target genes in B. tabaci, will enable determining a specific linkage between gene expression and host related performance in this species. 3 hybridizations were performed for RNA extracted from Bemisia tabaci adults that fed on PAP Purple transgenic tobacco plants for 6hr, labeled with Cy5 and directly hybridized against 3 samples from B. tabaci adults that fed on wild type plants as a control and labeled with Cy3. Another 3 swap dye hybridizations were performed in which adults that fed on wild type plants for 6hr were coupled with the Cy5 and adults that fed on PAP Purple transgenic plants were coupled with Cy3.