Analysis of Expressed Proteins in Fiber Fractions from Insect‐Protected and Glyphosate‐Tolerant Cotton Varieties

Abstract

The objective of this study was to determine the concentration of introduced proteins in the fiber fractions of transgenic cotton (Gossypium hirsutum L.) before and after processing. Two novel cotton varieties were developed by genetic transformation technology. One variety expressed the CryIA(c) insecticidal protein derived from Bacillus thuringiensis var. kurstaki. The second cotton variety expressed the CP4 EPSPS (5‐enolpyruvyl shikimate‐3‐phosphate synthase) protein, originally found in Agrobacterium sp., which confers tolerance to glyphosate herbicide. Levels of the CryIA(c) and CP4 EPSPS proteins in raw lint, combed lint, raw linters, and processed linter brown stock from these cotton varieties were analyzed by means of western blot, insect bioassay [for CryIA(c) protein only], or both. The CryIA(c) protein was present in raw linters (0.17 μg g−1), but it was not detected in either raw or combed lint. The CP4 EPSPS protein was detected at low levels (<0.5 μg g−1) in combed lint, but not in processed linter brown stock. Inactivation of the CryIA(c) and CP4 EPSPS proteins in the first processing step for linters indicates that these proteins will not be present in cotton linter products. Similarly, the typical heat and chemical processing of cotton lint should also denature any transgenic protein(s) present.

Baseline toxicity of Cry1A toxins to Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) in India

“…Geographical variation in susceptibility to Bt toxins through baseline susceptibility studies was earlier reported for the related species H. virescens and H. zea (Sims et al, 1996). The LC 99 estimates for the full-length Cry1Ac protein were significantly different at 6.6 lg/ml for H. virescens, and 13 322 lg/ml for H. zea.…”

“…After examining the genetic and logistical implications of resistance monitoring methods, Roush and Miller (1986) concluded that discriminating dose assays were more efficient than the log dose probit regression assays in monitoring for resistance (Roush and Miller, 1986). Sims et al (1996) estimated diagnostic doses for Heliothis virescens (Fabricius) and Helicoverpa zea (Boddie) empirically, and suggested that the most practical approach for dose validation was to use individuals sampled from numerous populations within the geographic range of the species. The diagnostic doses derived from the present data incorporate the significant differences in Cry1A susceptibility among H. armigera populations from different geographic locations within India.…”

“…The proteins thus produced contained 40, 58 and 38% of the full-length Cry1Aa, Cry1Ab and Cry1Ac toxins respectively. Because transgenic cotton produces the non-activated, full length Cry1Ac protein (~130 kDa) (Sims et al, 1996), the LC 50 and LC 99 values were determined for the full-length Cry1A proteins.…”

Genetic Variation for Resistance to <I>Bacillus thuringiensis</I> Toxins in <I>Helicoverpa zea</I> (Lepidoptera: Noctuidae) in Eastern North Carolina

“…Cry1Ac (MVPII, Mycogen Corp., San Diego, CA) was obtained as a gift. Cry2Ab was acquired by producing lyophilized corn tissue containing the Cry2Ab toxin and grinding the tissue into powder; Monsanto Company determined the concentration of Cry2Ab within the corn powder by using a toxinspeciÞc enzyme-linked immunosorbent assays as described by Sims et al (1996). Diet was poured into 24-well plastic bioassay plates (Corrigan and Company Inc., Jacksonville, FL) and refrigerated before use.…”

Characterization of Bacillus thuringiensis isolates and their differential toxicity against Helicoverpa armigera populations

“…One of the important factors that can influence the efficacy of Btk for H. armigera management is the variability in the susceptibility to the Btk in different populations across the regions of the country. Sims et al [29] suggested that the most practical approach to dose validation was to use individuals sampled from numerous populations within the geographic range of the species. The data presented herein attempts to understand the changes that would have occurred in Btk susceptibility among H. armigera populations from eight different geographic locations within three states of Southern India.…”