Absence of protein polymorphism attributable to insecticide-insensitivity of acetylcholinesterase in the green rice leafhopper, Nephotettix cincticeps

The cDNA sequence of acetylcholinesterase (AChE) from the green rice leafho pper, Nephotettix cincticeps, was amplified, based on conserved peptide seq uences of AChEs. A 2.3 kb contiguous sequence, containing an ORF encoding a n AChE precursor with 677 amino acid residues was obtained. The deduced pro tein sequence showed the most similarity to that of AChE in the Colorado po tato beetle, having common features in the primary AChE structure, cDNA seq uences of individual Leafhoppers from an insecticide susceptible strain and the resistant strain Nakagawara, whose methylcarbamate-insensitive AChEs s how 10(2) or more I-50 ratio for propoxur, were compared. No fixed inter-st rain difference was identified in the protein sequence, though amino acid s ubstitution polymorphism was found at one position in the susceptible strai n. Insecticide-insensitivity of leafhopper AChE does not result from change s in the protein primary structure that is encoded by the AChE gene sequenc e isolated in this study. (C) 2000 Elsevier Science Ltd. All rights reserve d.