Tissue and life stage specificity of glutathione S-transferase expression in the Hessian fly, Mayetiola destructor: Implications for resistance to host allelochemicalsOmprakash Mittapalli1, Jonathan J. Neal1 and Richard H. Shukle1,2 1 Department of Entomology, Purdue University, West Lafayette, USA
2 USDA-ARS, Department of Entomology, Purdue University, West Lafayette, USA
AbstractTwo new Delta and Sigma glutathione S-transferases (GSTs) in the Hessian fly, Mayetiola destructor (Diptera: Cecidomyiidae), were characterized and transcription profiles described. The deduced amino acid sequences for the two M. destructor Delta GSTs (MdesGST-1 and MdesGST-3) showed high similarity with other insect Delta GSTs including the conserved catalytic serine residue. The deduced amino acid sequence for the M. destructor Sigma GST (MdesGST-2) showed high similarity with other insect Sigma GSTs including the conserved glutathione and substrate binding sites. Quantitative tissue expression analysis showed that mRNA levels for MdesGST-1 were predominant in fat body, whereas for MdesGST-2 and MdesGST-3 expression was predominant in the midgut. Temporal expression during development showed peak mRNA levels for MdesGST-1 during larval development, but in the pupal stage for MdesGST-2. MdesGST-3 showed a constitutive expression pattern throughout development. M. destructor feeds on wheat, and expression analysis after feeding indicated that mRNA levels for MdesGST-1 were significantly higher in incompatible interactions in which larvae fed on resistant wheat, while MdesGST-3 was significantly higher in compatible interactions when larvae fed on susceptible wheat. MdesGST-2 showed an equivalent expression pattern during both interactions. These results suggest that the M. destructor Delta GSTs are important in detoxifying wheat allelochemicals during feeding, while Sigma GST participates in metabolism of endogenous substrates. Keywords: wheat, allelochemicals, mRNA, MdesGST-1, MdesGST-2, MdesGST-3
Abbreviations: MdesGST-1, Mayetiola destructor glutathione S-transferase-1, MdesGST-2, Mayetiola destructor glutathione S-transferase-2, MdesGST-3, Mayetiola destructor glutathione S-transferase-3, REV, relative expression value
Correspondence: omittapalli@ice.mpg.de, jneal@purdue.edu, shukle@purdue.edu Received: 21 June 2006 | Accepted: 13 October 2006 | Published: 9 April 2007 Copyright: This is an open access paper. We use the Creative Commons Attribution 2.5 license that permits unrestricted use, provided that the paper is properly attributed. ISSN: 1536-2442 | Volume 7, Number 20
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