Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/3/2005
Publication Date: 1/3/2005
Citation: Hinze, L.L., Kohel, R.J. 2005. Evaluation of a commercially available ELISA kit for quantifying cry1ac production in geneticaclly engineered cotton. In: Proceedings of the Beltwide Cotton Conferences, January 4-7, 2005, New Orleans, Louisiana. 2005 CDROM. Interpretive Summary: An ELISA kit was identified that reportedly could be used to measure the amount of Cry1Ac, a Bt protein, produced in the leaves of plants. Cotton plants producing the Cry1Ac protein were genetically altered to not have the glands that are normally present in cotton. The objective was first to visually identify glandless plants and then use this kit to identify two groups of those glandless plants producing different amounts of the Cry1Ac protein. Glandless plants were easily identified visually. The ELISA kit was able to detect a range in values of Cry1Ac production in the glandless cotton plants but was unable to identify two distinct groups of glandless plants with the highest values for continued evaluation. After this study concluded, the ELISA kit was discontinued, but alternative kits may be modified to quantify Cry1Ac production. Glandless cotton has low levels of a natural compound that is toxic to poultry and swine. This research is of interest to other scientists working to incorporate the glandless trait into modern cotton varieties that produce Bt proteins so the cotton seed may be fed to poultry and swine.
Technical Abstract: Several genes from Bacillus thuringiensis (Bt) have been genetically engineered into cotton (Gossypium spp.) plants to promote insect resistance. In one instance, the insect resistance in these engineered plants is a result of an introduced Bt gene coding for the production of the Cry1Ac protein. The amount of Cry1Ac proteins produced in four cotton backcross populations and their respective recurrent Bt-containing parents was quantified using the ELISA-based Envirologix QuantiPlate Kit for Cry1Ac. Our main objective was to identify plants with two copies of the Bt gene (homozygous) versus those with one copy (heterozygous). The results clearly indicated the lack of Cry1Ac protein in our negative control while showing a continuous range of values for those plants expressing Cry1Ac. There was no definite break among the values that would indicate heterozygotes versus homozygotes having twice the expression level of the heterozygotes. Although we were unable to identify homozygotes with this kit, the kit is easy to use and effective for selecting those plants with the highest Cry1Ac expression.