Quantification of Bacillus thuringiensis Insect Control Protein Cry1Ac Over Time in Bollgard Cotton Fruit and Terminals

Greenplate, John T.

doi:10.1093/jee/92.6.1377

Cited by 182 publications

(134 citation statements)

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“…However, unlike our results showing similar seasonal declines of about threefold in Cry1Ac and Cry2Ab in DP 164 B2RF, previous studies with other cultivars found that the seasonal decline in toxin concentration was generally less for Cry2Ab (35)(36)(37) than Cry1Ac (38)(39)(40)(41)(42). In any case, seasonal declines in the concentration of Bt toxins could be an important factor affecting redundant killing because there is extensive variation among cotton cultivars in patterns of production of Bt toxins (43).…”

Section: Discussioncontrasting

confidence: 98%

Potential shortfall of pyramided transgenic cotton for insect resistance management

Brévault

Heuberger

Zhang

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

150

222

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To delay evolution of pest resistance to transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt), the "pyramid" strategy uses plants that produce two or more toxins that kill the same pest. In the United States, this strategy has been adopted widely, with two-toxin Bt cotton replacing one-toxin Bt cotton. Although two-toxin plants are likely to be more durable than one-toxin plants, the extent of this advantage depends on several conditions. One key assumption favoring success of two-toxin plants is that they kill insects selected for resistance to one toxin, which is called "redundant killing." Here we tested this assumption for a major pest, Helicoverpa zea, on transgenic cotton producing Bt toxins Cry1Ac and Cry2Ab. Selection with Cry1Ac increased survival on two-toxin cotton, which contradicts the assumption. The concentration of Cry1Ac and Cry2Ab declined during the growing season, which would tend to exacerbate this problem. Furthermore, analysis of results from 21 selection experiments with eight species of lepidopteran pests indicates that some cross-resistance typically occurs between Cry1A and Cry2A toxins. Incorporation of empirical data into simulation models shows that the observed deviations from ideal conditions could greatly reduce the benefits of the pyramid strategy for pests like H. zea, which have inherently low susceptibility to Bt toxins and have been exposed extensively to one of the toxins in the pyramid before two-toxin plants are adopted. For such pests, the pyramid strategy could be improved by incorporating empirical data on deviations from ideal assumptions about redundant killing and cross-resistance. (Résumé d'auteur

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Section: Discussioncontrasting

confidence: 98%

Potential shortfall of pyramided transgenic cotton for insect resistance management

Brévault

Heuberger

Zhang

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

150

222

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“…Only one dilution per sample was used (100 ppm). For WCR and TBW bioassays, microtiter plates with 96 wells were prepared with a synthetic insect diet (BioServ Co., Frenchtown, NJ) at a concentration of 200 μL per well), and 20 μL of the 1 mg/mL sample solution was pipetted onto the top of each of 16 wells for each insect (41,42). For WTPB bioassays, the dilutions were as described above for WCR and TBW but the samples were fed to WTPB using a Mylar-based sachet system (43).…”

Section: Assay Proceduresmentioning

confidence: 99%

Marine Natural Products as Prototype Agrochemical Agents

Peng

Shen²,

Ka³

et al. 2003

J. Agric. Food Chem.

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In the interest of identifying new leads that could serve as prototype agrochemical agents, 18 structurally diverse marine-derived compounds were examined for insecticidal, herbicidal, and fungicidal activities. Several new classes of compounds have been shown to be insecticidal, herbicidal, and fungicidal, which suggests that marine natural products represent an intriguing source for the discovery of new agrochemical agents.

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“…Holt (1998) correlated this decline in Bollgard cultivars to increased survival of H. armigera. Furthermore, season-long differences in expression among cultivars can vary as much as 2-fold throughout the season , and plant structures, such as terminal leaves, express more Cry1Ac compared with certain flower structures (Greenplate, 1999;Greenplate et al, 2000;Gore et al, 2001). Therefore, control strategies may be further compromised by the differential expression of Cry1Ac among plant structures and cultivars that create a spatial source for survivors to develop.…”

mentioning

confidence: 99%

Quantification of Cry1Ac and Cry1F <I>Bacillus thuringiensis</I> Insecticidal Proteins in Selected Transgenic Cotton Plant Tissue Types

Siebert¹,

Patterson²,

Gilles³

et al. 2009

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The amount of Cry1Ac δ-endotoxin in transgenic Bacillus thuringiensis Berliner (Bt) or Bollgard cotton varies among commercial cultivars. These differences in expression have been correlated with survival levels in Lepidoptera, indicating that all Bollgard cultivars do not provide the same level of control. The objective of this study was to determine if differences in overall expression among commercial cultivars of Bollgard cotton were under simple genetic control. These findings could influence the way breeders select cultivars by evaluating for efficacy in insect control in addition to agronomic traits. Two sets of crosses were made in the greenhouse with cultivars that express the endotoxin at high and low levels. The parents and F 1 and F 2 generations were planted in the field. The amount of Cry1Ac was quantified using a commercial ELISA kit. Variances within the two F 2 breeding populations were highly significant because of genetic segregation for Cry1Ac expression. Using the modified Castle-Wright formula, the estimation of the number of contributing genes in both breeding populations was small. These data show that genetic background has a major effect on Cry1Ac expression. Because backcrossing is the primary method used by commercial cotton breeders, the selection and use of donor and/or recurrent parents that will result in a high level of Cry1Ac expression is crucial.

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Quantification of Bacillus thuringiensis Insect Control Protein Cry1Ac Over Time in Bollgard Cotton Fruit and Terminals

Cited by 182 publications

References 0 publications

Potential shortfall of pyramided transgenic cotton for insect resistance management

Potential shortfall of pyramided transgenic cotton for insect resistance management

Marine Natural Products as Prototype Agrochemical Agents

Quantification of Cry1Ac and Cry1F <I>Bacillus thuringiensis</I> Insecticidal Proteins in Selected Transgenic Cotton Plant Tissue Types

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