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A toxin-binding alkaline phosphatase fragment synergizes Bt toxin Cry1Ac against susceptible and resistant Helicoverpa armigera.

Chen W, Liu C, Xiao Y, Zhang D, Zhang Y, Li X, Tabashnik BE, Wu K - PLoS ONE (2015)

Bottom Line: Reduced activity and reduced transcription of an alkaline phosphatase protein that binds Cry1Ac was associated with resistance to Cry1Ac in the four most resistant strains.Although synergism of Bt toxins against susceptible insects by toxin-binding fragments of cadherin and aminopeptidase N has been reported previously, the results here provide the first evidence of synergism of a Bt toxin by a toxin-binding fragment of alkaline phosphatase.The results here also provide the first evidence of synergism of a Bt toxin by any toxin-binding peptide against resistant insects.

View Article: PubMed Central - PubMed

Affiliation: The State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, West Yuanmingyuan Road, Beijing, 100193, China.

ABSTRACT
Evolution of resistance by insects threatens the continued success of pest control using insecticidal crystal (Cry) proteins from the bacterium Bacillus thuringiensis (Bt) in sprays and transgenic plants. In this study, laboratory selection with Cry1Ac yielded five strains of cotton bollworm, Helicoverpa armigera, with resistance ratios at the median lethal concentration (LC50) of activated Cry1Ac ranging from 22 to 1700. Reduced activity and reduced transcription of an alkaline phosphatase protein that binds Cry1Ac was associated with resistance to Cry1Ac in the four most resistant strains. A Cry1Ac-binding fragment of alkaline phosphatase from H. armigera (HaALP1f) was not toxic by itself, but it increased mortality caused by Cry1Ac in a susceptible strain and in all five resistant strains. Although synergism of Bt toxins against susceptible insects by toxin-binding fragments of cadherin and aminopeptidase N has been reported previously, the results here provide the first evidence of synergism of a Bt toxin by a toxin-binding fragment of alkaline phosphatase. The results here also provide the first evidence of synergism of a Bt toxin by any toxin-binding peptide against resistant insects.

No MeSH data available.


Related in: MedlinePlus

Effect of HaALP1f on toxicity of Cry1Ac activated toxin to a susceptible strain (96S) of H. armigera.The ratio of HaALP1f:Cry1Ac was 15:1 by weight. Asterisks denote significantly higher mortality with a mixture of HaALP1f and Cry1Ac than with Cry1Ac alone (P < 0.05) at a particular concentration of Cry1Ac.
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pone.0126288.g008: Effect of HaALP1f on toxicity of Cry1Ac activated toxin to a susceptible strain (96S) of H. armigera.The ratio of HaALP1f:Cry1Ac was 15:1 by weight. Asterisks denote significantly higher mortality with a mixture of HaALP1f and Cry1Ac than with Cry1Ac alone (P < 0.05) at a particular concentration of Cry1Ac.

Mentions: We tested for synergism in a series of bioassays that examined mortality caused by Cry1Ac activated toxin alone, HaALP1f alone, and combinations of various concentrations of Cry1Ac activated toxin and HaALP1f. For each of the six susceptible and resistant strains of H. armigera, one or more combinations of HaALP1f and Cry1Ac caused significantly higher mortality than Cry1Ac alone (Figs 7 and 8). For each of the six strains, HaALP1f was not toxic by itself, as indicated by the lack of significant difference in mortality between HaALP1f in PBS buffer alone and the control with only the PBS buffer (6 pairwise comparisons, P > 0.05 in each comparison, Fig 7). In addition, with the data from all six strains pooled, mortality did not differ significantly between the PBS buffer with HaALP1f (mean = 10.9%, 95% confidence interval = 8.6 to 13.2) and the PBS buffer without HaALP1f (mean = 8.6%, 95% confidence interval = 5.8 to 11.4%; t-test, t = 1.36, df = 34, P = 0.18). Therefore, the significantly increased mortality seen with the combination of HaALP1f and Cry1Ac was caused by synergism, rather than independent toxicity of HaALP1f.


A toxin-binding alkaline phosphatase fragment synergizes Bt toxin Cry1Ac against susceptible and resistant Helicoverpa armigera.

Chen W, Liu C, Xiao Y, Zhang D, Zhang Y, Li X, Tabashnik BE, Wu K - PLoS ONE (2015)

Effect of HaALP1f on toxicity of Cry1Ac activated toxin to a susceptible strain (96S) of H. armigera.The ratio of HaALP1f:Cry1Ac was 15:1 by weight. Asterisks denote significantly higher mortality with a mixture of HaALP1f and Cry1Ac than with Cry1Ac alone (P < 0.05) at a particular concentration of Cry1Ac.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4401514&req=5

pone.0126288.g008: Effect of HaALP1f on toxicity of Cry1Ac activated toxin to a susceptible strain (96S) of H. armigera.The ratio of HaALP1f:Cry1Ac was 15:1 by weight. Asterisks denote significantly higher mortality with a mixture of HaALP1f and Cry1Ac than with Cry1Ac alone (P < 0.05) at a particular concentration of Cry1Ac.
Mentions: We tested for synergism in a series of bioassays that examined mortality caused by Cry1Ac activated toxin alone, HaALP1f alone, and combinations of various concentrations of Cry1Ac activated toxin and HaALP1f. For each of the six susceptible and resistant strains of H. armigera, one or more combinations of HaALP1f and Cry1Ac caused significantly higher mortality than Cry1Ac alone (Figs 7 and 8). For each of the six strains, HaALP1f was not toxic by itself, as indicated by the lack of significant difference in mortality between HaALP1f in PBS buffer alone and the control with only the PBS buffer (6 pairwise comparisons, P > 0.05 in each comparison, Fig 7). In addition, with the data from all six strains pooled, mortality did not differ significantly between the PBS buffer with HaALP1f (mean = 10.9%, 95% confidence interval = 8.6 to 13.2) and the PBS buffer without HaALP1f (mean = 8.6%, 95% confidence interval = 5.8 to 11.4%; t-test, t = 1.36, df = 34, P = 0.18). Therefore, the significantly increased mortality seen with the combination of HaALP1f and Cry1Ac was caused by synergism, rather than independent toxicity of HaALP1f.

Bottom Line: Reduced activity and reduced transcription of an alkaline phosphatase protein that binds Cry1Ac was associated with resistance to Cry1Ac in the four most resistant strains.Although synergism of Bt toxins against susceptible insects by toxin-binding fragments of cadherin and aminopeptidase N has been reported previously, the results here provide the first evidence of synergism of a Bt toxin by a toxin-binding fragment of alkaline phosphatase.The results here also provide the first evidence of synergism of a Bt toxin by any toxin-binding peptide against resistant insects.

View Article: PubMed Central - PubMed

Affiliation: The State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, West Yuanmingyuan Road, Beijing, 100193, China.

ABSTRACT
Evolution of resistance by insects threatens the continued success of pest control using insecticidal crystal (Cry) proteins from the bacterium Bacillus thuringiensis (Bt) in sprays and transgenic plants. In this study, laboratory selection with Cry1Ac yielded five strains of cotton bollworm, Helicoverpa armigera, with resistance ratios at the median lethal concentration (LC50) of activated Cry1Ac ranging from 22 to 1700. Reduced activity and reduced transcription of an alkaline phosphatase protein that binds Cry1Ac was associated with resistance to Cry1Ac in the four most resistant strains. A Cry1Ac-binding fragment of alkaline phosphatase from H. armigera (HaALP1f) was not toxic by itself, but it increased mortality caused by Cry1Ac in a susceptible strain and in all five resistant strains. Although synergism of Bt toxins against susceptible insects by toxin-binding fragments of cadherin and aminopeptidase N has been reported previously, the results here provide the first evidence of synergism of a Bt toxin by a toxin-binding fragment of alkaline phosphatase. The results here also provide the first evidence of synergism of a Bt toxin by any toxin-binding peptide against resistant insects.

No MeSH data available.


Related in: MedlinePlus