title: Genetic Conservation of Phosphine Resistance in the Rice Weevil Sitophilus oryzae (L.).
abstract: High levels of resistance to phosphine in the rice weevil Sitophilus oryzae have been detected in Asian countries including China and Vietnam, however there is limited knowledge of the genetic mechanism of resistance in these strains. We find that the genetic basis of strong phosphine resistance is conserved between strains of S. oryzae from China, Vietnam, and Australia. Each of 4 strongly resistant strains has an identical amino acid variant in the encoded dihydrolipoamide dehydrogenase (DLD) enzyme that was previously identified as a resistance factor in Rhyzopertha dominica and Tribolium castaneum. The unique amino acid substitution, Asparagine > Threonine (N505T) of all strongly resistant S. oryzae corresponds to the position of an Asparagine > Histidine variant (N506H) that was previously reported in strongly resistant R. dominica. Progeny (F16 and F18) from 2 independent crosses showed absolute linkage of N505T to the strong resistance phenotype, indicating that if N505T was not itself the resistance variant that it resided within 1 or 2 genes of the resistance factor. Non-complementation between the strains confirmed the shared genetic basis of strong resistance, which was supported by the very similar level of resistance between the strains, with LC50 values ranging from 0.20 to 0.36 mg L(-1) for a 48-h exposure at 25 °C. Thus, the mechanism of high-level resistance to phosphine is strongly conserved between R. dominica, T. castaneum and S. oryzae. A fitness cost associated with strongly resistant allele was observed in segregating populations in the absence of selection.
authors.affiliation: From the School of Biological Sciences, University of Queensland, St. Lucia, Queensland, Australia (Nguyen and Ebert); Faculty of Biology, Hanoi National University of Education, Hanoi, Vietnam (Nguyen); Department of Agriculture, Fisheries and Forestry, Ecosciences Precinct, Brisbane, Queensland, Australia (Collins and Schlipalius); and Plant Protection Department, Ministry of Agriculture and Rural Development, Hanoi, Vietnam (Duong).
authors.forename: Tam T
authors.initials: TT
authors.lastname: Nguyen
authors.affiliation: From the School of Biological Sciences, University of Queensland, St. Lucia, Queensland, Australia (Nguyen and Ebert); Faculty of Biology, Hanoi National University of Education, Hanoi, Vietnam (Nguyen); Department of Agriculture, Fisheries and Forestry, Ecosciences Precinct, Brisbane, Queensland, Australia (Collins and Schlipalius); and Plant Protection Department, Ministry of Agriculture and Rural Development, Hanoi, Vietnam (Duong).
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Collins
authors.affiliation: From the School of Biological Sciences, University of Queensland, St. Lucia, Queensland, Australia (Nguyen and Ebert); Faculty of Biology, Hanoi National University of Education, Hanoi, Vietnam (Nguyen); Department of Agriculture, Fisheries and Forestry, Ecosciences Precinct, Brisbane, Queensland, Australia (Collins and Schlipalius); and Plant Protection Department, Ministry of Agriculture and Rural Development, Hanoi, Vietnam (Duong).
authors.forename: Tu M
authors.initials: TM
authors.lastname: Duong
authors.affiliation: From the School of Biological Sciences, University of Queensland, St. Lucia, Queensland, Australia (Nguyen and Ebert); Faculty of Biology, Hanoi National University of Education, Hanoi, Vietnam (Nguyen); Department of Agriculture, Fisheries and Forestry, Ecosciences Precinct, Brisbane, Queensland, Australia (Collins and Schlipalius); and Plant Protection Department, Ministry of Agriculture and Rural Development, Hanoi, Vietnam (Duong).
authors.forename: David I
authors.initials: DI
authors.lastname: Schlipalius
authors.affiliation: From the School of Biological Sciences, University of Queensland, St. Lucia, Queensland, Australia (Nguyen and Ebert); Faculty of Biology, Hanoi National University of Education, Hanoi, Vietnam (Nguyen); Department of Agriculture, Fisheries and Forestry, Ecosciences Precinct, Brisbane, Queensland, Australia (Collins and Schlipalius); and Plant Protection Department, Ministry of Agriculture and Rural Development, Hanoi, Vietnam (Duong). p.ebert@uq.edu.au.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Ebert
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001315:Australia; D002681:China; D008058:Dihydrolipoamide Dehydrogenase / Q000235:genetics*; D005816:Genetic Complementation Test; D056084:Genetic Fitness; D008040:Genetic Linkage; D007305:Insecticide Resistance / Q000235:genetics*; D008969:Molecular Sequence Data; D012275:Oryza; D010641:Phenotype; D010720:Phosphines; D020641:Polymorphism, Single Nucleotide; D016415:Sequence Alignment; D017423:Sequence Analysis, RNA; D059467:Transcriptome; D014744:Vietnam; D048889:Weevils / Q000201:enzymology / Q000235:genetics*
chemical_list: D010720:Phosphines; D008058:Dihydrolipoamide Dehydrogenase; C044646:phosphine
keywords: dihydrolipoamide dehydrogenase; fitness cost; mode of inheritance; rph2 gene