Submitted to: Insect Biochemistry and Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/31/2005
Publication Date: 9/1/2005
Citation: Mittapalli, O., Neal, J.J., Shukle, R.H. 2005. Differential expression of two cytochrome p450 genes in compatible and incompatible hessian fly/wheat interactions. Insect Biochemistry and Molecular Biology. 35:981-989. Interpretive Summary: The Hessian fly is the most destructive insect pest of wheat worldwide including the United States. Losses in Georgia due to the Hessian fly were estimated at $28 million in 1989. Resistant wheat is the most economical and environmentally sound method of control. However, the emergence of biotypes of the pest that can survive on formally resistant wheat is a threat to long-term protection of wheat. Despite its importance as a pest of wheat, knowledge of the Hessian fly and its interaction with wheat at the molecular level is very limited. This restricts application of modern molecular and genomic approaches to enhance durable protection of wheat from the pest. From an ongoing project to identify Hessian fly genes that can influence its ability to survive on wheat we have identified and characterized two genes that produce enzymes (called 'P450s') in the gut of feeding Hessian fly larvae, which are critical to the detoxification of chemicals that plants produce to defend themselves from insect pests. Knowledge from these studies will help breeders and scientists facing the challenge of devising innovative methods for plant resistance to ensure durable resistant wheat cultivars to prevent yield loss due to Hessian fly infestation. The agricultural community (crop producers and commodity groups) will benefit from improved pest control that increases yield and quality without increasing costs.
Technical Abstract: We have recovered two Hessian fly cytochrome P450 cDNAs from an ongoing midgut EST project. CYP6AZ1 and CYP6BA1 represent two new subfamilies within the CYP6 family. The deduced amino acid sequences for CYP6AZ1 and CYP6BA1 show conserved structural and functional domains of insect P450s. A phylogenetic tree that included other CYP families of insects revealed that CYP6AZ1 and CYP6BA1 were most closely related to Culex pipiens quinquefasciatus CYP6F1 and Musca domestica CYP6D3V2, respectively. Expression analysis with reverse transcription polymerase chain reaction (RT-PCR) indicated that CYP6AZ1 is midgut specific and induced during active larval feeding, whereas CYP6BA1 was expressed in all tissues and developmental stages examined. Further expression analysis of CYP6AZ1 with semi-quantitative RT-PCR in compatible and incompatible Hessian fly/wheat interactions suggested that CYP6AZ1 may be required for larval feeding in compatible interactions. These results should lead to a better understanding of the Hessian fly/wheat interaction with emphasis on the larval midgut as a critical interface with its host plant.