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Inheritance and characterization of strong resistance to phosphine in Sitophilus oryzae (L.).

Nguyen TT, Collins PJ, Ebert PR - PLoS ONE (2015)

Bottom Line: Sitophilus oryzae (Linnaeus) is a major pest of stored grain across Southeast Asia and is of increasing concern in other regions due to the advent of strong resistance to phosphine, the fumigant used to protect stored grain from pest insects.Analysis of F2 and backcross progeny indicates that two or more genes are responsible for strong resistance, and that one of these genes, designated So_rph1, not only contributes to strong resistance, but is also responsible for the weak resistance phenotype of strain QSO335.These results demonstrate that the genetic mechanism of phosphine resistance in S. oryzae is similar to that of other stored product insect pests.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Queensland, St. Lucia, Queensland, Australia; Faculty of Biology, Hanoi National University of Education, Hanoi, Vietnam.

ABSTRACT
Sitophilus oryzae (Linnaeus) is a major pest of stored grain across Southeast Asia and is of increasing concern in other regions due to the advent of strong resistance to phosphine, the fumigant used to protect stored grain from pest insects. We investigated the inheritance of genes controlling resistance to phosphine in a strongly resistant S. oryzae strain (NNSO7525) collected in Australia and find that the trait is autosomally inherited and incompletely recessive with a degree of dominance of -0.66. The strongly resistant strain has an LC50 52 times greater than a susceptible reference strain (LS2) and 9 times greater than a weakly resistant strain (QSO335). Analysis of F2 and backcross progeny indicates that two or more genes are responsible for strong resistance, and that one of these genes, designated So_rph1, not only contributes to strong resistance, but is also responsible for the weak resistance phenotype of strain QSO335. These results demonstrate that the genetic mechanism of phosphine resistance in S. oryzae is similar to that of other stored product insect pests. A unique observation is that a subset of the progeny of an F1 backcross generation are more strongly resistant to phosphine than the parental strongly resistant strain, which may be caused by multiple alleles of one of the resistance genes.

No MeSH data available.


Related in: MedlinePlus

Probit analysis of mortality due to phosphine exposure: W-strain x R-strain intercross.Percent mortality was determined after a 48 h exposure to phosphine at 25°C followed by a week recovery period. Results for weakly resistant (W-strain) and strongly resistant (R-strain) insects are provided for reference. Experimental data for reciprocal F1 and F2 progeny are shown. A theoretical mortality response curve for the F2 is drawn based on the hypothesis that only a single gene contributes to the observed resistance.
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pone.0124335.g003: Probit analysis of mortality due to phosphine exposure: W-strain x R-strain intercross.Percent mortality was determined after a 48 h exposure to phosphine at 25°C followed by a week recovery period. Results for weakly resistant (W-strain) and strongly resistant (R-strain) insects are provided for reference. Experimental data for reciprocal F1 and F2 progeny are shown. A theoretical mortality response curve for the F2 is drawn based on the hypothesis that only a single gene contributes to the observed resistance.

Mentions: The response of W-strain to phosphine (Table 2) indicated that it was homogeneous (P = 0.068), whereas those of the R-strain, F1 (♀W-strain x ♂R-strain) and F1 (♀R-strain x ♂W-strain) exhibited considerable heterogeneity (P < 0.001 and hf = 8.55, 6.94, 6.42, respectively). The resistance at the LC50 of the W-strain was 9 times less than that of the R-strain but 6 times greater than that of the S-strain. The degree of dominance based on the response of the F1 (♀W-strain x ♂R-strain) and F1 (♀R-strain x ♂W-strain) progeny was -0.38 and -0.41, respectively (Table 2), indicating that the strong resistance trait was incompletely recessive. The ld-pm lines of the reciprocal F1 hybrids overlapped (Fig 3) and the relative potency between F1 (♀W-strain x ♂R-strain) and F1 (♀R-strain x ♂W-strain) was 1.033 [0.9023–1.184, 95%CL], showing that two data sets of the reciprocal F1 populations were statistically indistinguishable. Thus, strong resistance relative to weak resistance to phosphine in S. oryzae was neither sex-linked nor maternally influenced, allowing data of reciprocal F1 crosses to be combined in the subsequent analysis.


Inheritance and characterization of strong resistance to phosphine in Sitophilus oryzae (L.).

Nguyen TT, Collins PJ, Ebert PR - PLoS ONE (2015)

Probit analysis of mortality due to phosphine exposure: W-strain x R-strain intercross.Percent mortality was determined after a 48 h exposure to phosphine at 25°C followed by a week recovery period. Results for weakly resistant (W-strain) and strongly resistant (R-strain) insects are provided for reference. Experimental data for reciprocal F1 and F2 progeny are shown. A theoretical mortality response curve for the F2 is drawn based on the hypothesis that only a single gene contributes to the observed resistance.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4401577&req=5

pone.0124335.g003: Probit analysis of mortality due to phosphine exposure: W-strain x R-strain intercross.Percent mortality was determined after a 48 h exposure to phosphine at 25°C followed by a week recovery period. Results for weakly resistant (W-strain) and strongly resistant (R-strain) insects are provided for reference. Experimental data for reciprocal F1 and F2 progeny are shown. A theoretical mortality response curve for the F2 is drawn based on the hypothesis that only a single gene contributes to the observed resistance.
Mentions: The response of W-strain to phosphine (Table 2) indicated that it was homogeneous (P = 0.068), whereas those of the R-strain, F1 (♀W-strain x ♂R-strain) and F1 (♀R-strain x ♂W-strain) exhibited considerable heterogeneity (P < 0.001 and hf = 8.55, 6.94, 6.42, respectively). The resistance at the LC50 of the W-strain was 9 times less than that of the R-strain but 6 times greater than that of the S-strain. The degree of dominance based on the response of the F1 (♀W-strain x ♂R-strain) and F1 (♀R-strain x ♂W-strain) progeny was -0.38 and -0.41, respectively (Table 2), indicating that the strong resistance trait was incompletely recessive. The ld-pm lines of the reciprocal F1 hybrids overlapped (Fig 3) and the relative potency between F1 (♀W-strain x ♂R-strain) and F1 (♀R-strain x ♂W-strain) was 1.033 [0.9023–1.184, 95%CL], showing that two data sets of the reciprocal F1 populations were statistically indistinguishable. Thus, strong resistance relative to weak resistance to phosphine in S. oryzae was neither sex-linked nor maternally influenced, allowing data of reciprocal F1 crosses to be combined in the subsequent analysis.

Bottom Line: Sitophilus oryzae (Linnaeus) is a major pest of stored grain across Southeast Asia and is of increasing concern in other regions due to the advent of strong resistance to phosphine, the fumigant used to protect stored grain from pest insects.Analysis of F2 and backcross progeny indicates that two or more genes are responsible for strong resistance, and that one of these genes, designated So_rph1, not only contributes to strong resistance, but is also responsible for the weak resistance phenotype of strain QSO335.These results demonstrate that the genetic mechanism of phosphine resistance in S. oryzae is similar to that of other stored product insect pests.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Queensland, St. Lucia, Queensland, Australia; Faculty of Biology, Hanoi National University of Education, Hanoi, Vietnam.

ABSTRACT
Sitophilus oryzae (Linnaeus) is a major pest of stored grain across Southeast Asia and is of increasing concern in other regions due to the advent of strong resistance to phosphine, the fumigant used to protect stored grain from pest insects. We investigated the inheritance of genes controlling resistance to phosphine in a strongly resistant S. oryzae strain (NNSO7525) collected in Australia and find that the trait is autosomally inherited and incompletely recessive with a degree of dominance of -0.66. The strongly resistant strain has an LC50 52 times greater than a susceptible reference strain (LS2) and 9 times greater than a weakly resistant strain (QSO335). Analysis of F2 and backcross progeny indicates that two or more genes are responsible for strong resistance, and that one of these genes, designated So_rph1, not only contributes to strong resistance, but is also responsible for the weak resistance phenotype of strain QSO335. These results demonstrate that the genetic mechanism of phosphine resistance in S. oryzae is similar to that of other stored product insect pests. A unique observation is that a subset of the progeny of an F1 backcross generation are more strongly resistant to phosphine than the parental strongly resistant strain, which may be caused by multiple alleles of one of the resistance genes.

No MeSH data available.


Related in: MedlinePlus