MOLECULAR CLONING, GENOMIC STRUCTURE, AND GENETIC MAPPING OF TWO RDL-ORTHOLOGOUS GENES OF GABA RECEPTORS IN THE DIAMONDBACK MOTH, Plutella xylostella

摘要

The Resistance to dieldrin (Rdl) gene encodes a subunit of the insect gamma-aminobutyric acid (GABA) receptor. Cyclodiene resistance in many insects is associated with replacement of a single amino acid (alanine at position 302) with either a serine or a glycine in the Rdl gene. Two Rdlorthologous genes of GABA receptors (PxGABARa1 and PxGABARa2) were cloned and sequenced from a susceptible strain (Roth) of Plutella xylostella. PxGABARa1 and PxGABARa2 showed 84% and 77% identity with the Rdl gene ofDrosophila melanogaster at an amino acid level, respectively. The coding regions of PxGABARa1 and PxGA- BAR alpha 2 both comprise ten exons, with two alternative RNA-splicing forms in exon 3 of both genes. At the orthologous position of alanine-302 in D.melanogaster Rdl, PxGABAR alpha 1 has a conserved alanine at position 282. PxGABARa2 has a serine instead of an alanine at the equivalent position. With two informative DNA markers, both PxGABARa1and PxGABARa2 were mapped onto the Z chromosome of P. xylostella.