Plant & Animal Genomes XIV Conference

January 14-18, 2006
Town & Country Convention Center
San Diego, CA

Positional Cloning Of A Phosphine Resistance Gene In The Lesser Grain Borer (Rhyzopertha dominica)

Yosep S. Mau^1,2,3 , Paul R. Ebert^1,2 , David Schlipalius¹ , Dave Merritt¹ , Juandy Jo² , Venkata G. Nidadavolu² , Pat J. Collins⁴

¹  School of Integrative Biology, Goddard Building (8), St Lucia Campus, The University of Queensland, Brisbane, Qld 4072 Australia

²  School of Molecular and Microbial Sciences Chemistry Building (69) St Lucia Campus The University of Queensland Brisbane Qld 4072 Australia

³  Universitas Nusa Cendana, Jln. Adisucipto Penfui Kupang, NTT 85001 Indonesia

⁴  Queensland Department of Primary Industries, 80 Meiers Street, Indooroopilly, QLD, Australia

Phosphine (PH3) is the fumigant of choice for controlling stored product insect pests. The emergence of resistance to this fumigant during the last two decades threatens the future use of phosphine and no comparable alternative exists. We are engaged in cloning of a phosphine resistance gene from R. dominica, a major insect pest of stored grain, in an effort to elucidate the mechanisms of resistance. This information will assist with the management of resistance as well as development of new fumigants. Two genes have been identified which confer phosphine resistance on an Australian strain of Rhyzopertha dominica, QRD569. Phr 1 provides weak resistance, and is found in other resistant strains across the country, indicating a common genetic mechanism of resistance. Phr 2, in interaction with phr 1, provides a strong resistance phenotype, about 250 times that of a susceptible reference strain. The resistance genes have been mapped and a tightly linked (0.01 cM) DNA marker has been used to initiate genome walking towards phr 2 from a phage genomic library constructed from a sensitive R. dominica strain. Two candidate genes have been identified: one of which encodes a splicing factor and the other a ligand-gated ion channel. The expression and function of both genes are now being tested using Quantitative Real Time PCR in R. dominica and RNAi in the model organism Caenorhabditis elegans.