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Genetic conservation of Phosphine Resistance in the Rice Weevil Sitophilus oryzae (L.)

Nguyen, Tam T. and Collins, Patrick J. and Duong, Tu M. and Schlipalius, David I. and Ebert, Paul R. (2016) Genetic conservation of Phosphine Resistance in the Rice Weevil Sitophilus oryzae (L.). Journal of Heredity .

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Article Link(s): http://dx.doi.org/10.1093/jhered/esw001

Publisher URL: http://jhered.oxfordjournals.org/content/early/2016/01/16/jhered.esw001.abstract

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 four 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 two 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 mgL-1 for a 48 hour 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.

Item Type:Article
Business groups:Crop and Food Science
Subjects:Science > Entomology
Plant culture > Field crops > Rice
Plant pests and diseases
Deposited On:09 Feb 2016 02:57
Last Modified:06 Apr 2016 02:42

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