A previous study documented a glycine to glutamic acid mutation (G4946E) in ryanodine receptor (RyR) was highly correlated to diamide insecticide resistance in field populations of Plutella xylostella (Lepidoptera: Plutellidae). In this study, a field population collected in Yunnan province, China, exhibited a 2128-fold resistance to chlorantraniliprole. Sequence comparison between resistant and susceptible P. xylostella revealed three novel mutations including a glutamic acid to valine substitution (E1338D), a glutamine to leucine substitution (Q4594L) and an isoleucine to methionine substitution (I4790M) in highly conserved regions of RyR. Frequency analysis of all four mutations in this field population showed that the three new mutations showed a high frequency of 100%, while the G4946E had a frequency of 20%. Furthermore, the florescent ligand binding assay revealed that the RyR containing multiple mutations displayed a significantly lower affinity to the chlorantraniliprole. The combined results suggested that the co-existence of different combinations of the four mutations was involved in the chlorantraniliprole resistance. An allele-specific PCR based method was developed for the diagnosis of the four mutations in the field populations of P. xylostella.
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This work was supported by the National Basic Research Programme of China (2012CB114103), the National 863 Plan (2012AA101502), the Special Fund for Agroscientific Research in the Public Interest (No. 201103021) and the National Natural Science Foundation of China (31171873 and 31371956). Preparation of fluorescent ligand was supported by the National S&T PillarProgram of China (2012BAK25B03) and the National Basic Research Program of China (2010CB126104).
Guo, Lei; Liang, Pei; Zhou, Xuguo; and Gao, Xiwu, "Novel Mutations and Mutation Combinations of Ryanodine Receptor in a Chlorantraniliprole Resistant Population of Plutella xylostella (L.)" (2014). Entomology Faculty Publications. 76.
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Figure 1: Position of four mutations in Plutella xylostella ryanodine receptor.
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Figure 2: Equilibrium binding of chlorantraniliprole fluorescent tracer to membrane protein of P. xylostella.
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Figure 3: Diagnosis of different genotypes of the mutations using allele-specific PCR.