Progress 02/15/11 to 02/14/16
Outputs
Target Audience:Scientists working on protecting crops from pests Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Graduate students and post-doctoral fellows have been trained. How have the results been disseminated to communities of interest?Yes, Results have been presented at scientific meetings and published in scientific journals. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Identification of enzymes that are upregulated in insecticide resistant strains and induced in response to ingestion of plant chemicals:We employed Colorado potato beetle (CPB) and its host plant, potato, as a model system. Next-generation sequencing (454 pyrosequencing) was performed to reveal the CPB transcriptome. Differential expression patterns of cytochrome P450 complement (CYPome) were analyzed between the susceptible (S) and imidacloprid resistant (R) beetles. We also evaluated the global transcriptome repertoire of CPB CYPome in response to the challenge by potato leaf allelochemicals and imidacloprid. The results showed that more than half (51.2%) of the CBP cytochrome P450 monooxygenases (P450s) that are up-regulated in the R strain are also induced by both host plant toxins and pesticide in a tissue-specific manner. These data suggest that xenobiotic adaptation in this specialist herbivore is through up-regulation of multiple P450s that are potentially involved in detoxifying both pesticide and plant allelochemicals. Molecular mechanisms of induction of detoxification enzymes:Previous studies in our laboratory showed that the pyrethroid resistance in QTC279 strain of Tribolium castaneum is achieved through constitutive overexpression of the P450 gene CYP6BQ9 by 200-fold higher in the resistant strain as compared to that in the susceptible strain. RNAi-aided knockdown in the expression of probable genes that regulate P450 gene expression in QTC279 identified cap 'n' collar C (CncC) and muscle aponeurosis fibromatosis (Maf) family transcription factors as the key regulator of these genes, CncC and Maf regulate expression of multiple genes in the CYP6BQ cluster. Studies on the promoters of these genes using reporter assays identified binding sites that mediate CncC and Maf regulation of CYP6BQ gene expression. We also showed that the CncC and Maf also regulate P450 genes that are upregulated in insecticide resistant strains and induced by insecticides and plant chemicals in the Colorado Potato beetle.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Zhu F, Moural TW, Nelson DR, Palli SR. (2016) A specialist herbivore pest adaptation to xenobiotics through up-regulation of multiple Cytochrome P450s.
Sci Rep. 2016 Feb 10;6:20421. doi: 10.1038/srep20421.
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Kalsi M, Palli SR. (2015) Transcription factors, CncC and Maf, regulate expression of CYP6BQ genes responsible for deltamethrin resistance in Tribolium castaneum.
Insect Biochem Mol Biol. 2015 Oct;65:47-56. doi: 10.1016/j.ibmb.2015.08.002. Epub 2015 Aug 7.
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Progress 02/15/13 to 02/14/14
Outputs
Target Audience: Scientists working on insecticide resistance Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Trained Post-doctoral fellow How have the results been disseminated to communities of interest? Manuscript is in preparation What do you plan to do during the next reporting period to accomplish the goals? We will continue studies on mechanisms of detoxification. Identification of transcription factors and the DNA elements they bind will be focus of our studies in the coming year.
Impacts
What was accomplished under these goals?
The adaptation of herbivorous insects to their host plants is hypothesized to be intimately connected with their ubiquitous development of resistance to insecticides. However, not much is known about the mechanisms underlying the relationship between detoxification of plant toxins and synthetic insecticides. Colorado potato beetle (CPB) and its host plant, potato, were used as a model system to test if CPB adaptation to host plant toxins is co-opted for its robust insecticide resistance abilities. We employed next-generation sequencing to identify 98 members of CPB CYPome from the imidacloprid resistant beetles. Expression profiles of CPB P450s in susceptible and imidacloprid resistant strains and their induction by both host plant toxins and imidacloprid were determined. Our studies revealed that about half of CBP P450s were induced by both host plant toxins and insecticide. Functional studies showed that CYP6BJ genes contribute to imidacloprid resistance in the R strain after their induction by plant toxins and imidacloprid. These results provide solid evidence that host plant toxin and insecticide inducible P450s contribute to imidacloprid resistance in CPB. The cross-resistance to both host plant toxins and insecticides by inducing the expression of P450 genes represents an adaptive plasticity or trade-off between conserving energy and enabling adjustment to a rapidly changing environment.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Zhu,F., Moural, T.W., Shah, K. and Palli, S.R. (2013)Integrated analysis of cytochrome P450 gene
superfamily in the red flour beetle, Tribolium castaneum. BMC Genomics 14:174
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Progress 02/15/12 to 02/14/13
Outputs
OUTPUTS: Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say) is a member of the most species-rich eukaryotic order (Coleoptera) which includes about 25% of animal species. CPB is an international pest and causes severe economic loss on potatoes all around the world. However, the management of CPB is a huge challenge because CPB has evolved a remarkable ability to develop resistance to a wide range of insecticides (1). CPB host plants in the family Solanaceae, which are natural food sources for this insect, contain high concentrations of toxic glycoalkaloids in their foliage. These toxins protect them from a wide range of herbivores. The coevolution of CPB with its host plants may contribute to its remarkable capability on developing insecticide resistance. We used next generation sequencing to decipher CPB CYPome and 98 P450 genes were identified and named. Then, we investigated differences in expression of identified P450s between susceptible and resistant strains. Induction of P450 mRNA by host plant allochemicals and insecticide in multiple tissues was monitored. The information we obtained in CPB may help to develop sustainable pest management strategies. PARTICIPANTS: Dr. Fang Zhu TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The information we obtained in CPB may help to develop sustainable pest management strategies.
Publications
- No publications reported this period
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Progress 02/15/11 to 02/14/12
Outputs
OUTPUTS: RNA interference (RNAi) is a breakthrough technology for conducting functional genomics studies and also as a potential tool for crop protection against insect pests. Themajor challenge for efficient pest control using RNAi in the field is the development of efficient and reliable methods for production and delivery of double-stranded RNA (dsRNA). In this project, the potential of feeding dsRNA expressed in bacteria or synthesized in vitro to manage populations of Colorado potato beetle, Leptinotarsa decemlineata (Say) (CPB), was investigated. Feeding RNAi successfully triggered the silencing of all five target genes tested and caused significant mortality and reduced body weight gain in the treated beetles. This study provides the first example of an effective RNAi response in insects after feeding dsRNA produced in bacteria. These results suggest that the efficient induction of RNAi using bacteria to deliver dsRNA is a possible method for management of CPB. This could be also a promising bioassay approach for genome-wide screens to identify effective target genes for use as novel RNAi-based insecticides. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
A new method was developed for controlling Colorado potato beetle
Publications
- Zhu, F., Xu, J., Palli, R., Ferguson, J. & Palli, S. R. (2011) Ingested RNA interference for managing the populations of the Colorado potato beetle, Leptinotarsa decemlineata, Pest Manag Sci. 67, 175-82.107.
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