|Kim, Kyung Seok|
Submitted to: Genetica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/9/2011
Publication Date: 8/6/2011
Citation: Coates, B.S., Sumerford, D.V., Lopez, M.D., Wang, H., Fraser, L.M., Kroemer, J.A., Spencer, T., Kim, K., Abel, C.A., Hellmich II, R.L., Siegfried, B.D. 2011. A single major QTL controls expression of larval Cry1F resistance trait in Ostrinia nubilalis (Lepidoptera: Crambidae) and is independent of midgut receptor genes. Genetica. 139(8):961-972. Interpretive Summary: Genetically-engineered (transgenic) crop plants kill targeted insects that feed upon them. Scientists and crop producers see benefits in these plants because they offer control of insect pests without the harmful environmental effects of conventional chemical insecticides. Reduced chemical usage translates into less surface and ground water contamination, and improved farm worker safety. European corn borer, an important pest of corn in the United States, is controlled by transgenic Bacillus thuringiensis (Bt) corn. Damage and control costs for this insect exceed $1 billion from an annual crop valued more than $22 billion. Nearly complete control of European corn borer on Bt transgenic corn, however, has many scientists concerned that this pest may become resistant to these plants. In this study genes previously shown to cause resistance to Bt toxins in other insect pests, alkaline phosphatase, aminopeptidase N, bre5 (Bt resistance gene 5), and cadherin were shown not to be involved in resistance to the Bt toxin Cry1F traits in the European corn borer. In contrast, we used other genetic markers to show that the Cry1F resistance trait for European corn borer is located in a different region of the genome, and may arise by a new mechanism not yet described in other species. The outcomes of this research provide stakeholders a molecular tool for characterization of possible resistance genes. The genetics of insect resistance will be useful for all stakeholders interested in finding novel ways to control European corn borers and sustain Bt technology.
Technical Abstract: European corn borer, Ostrinia nubilalis (Lepidoptera: Crambidae), is an introduced crop pest in North America that causes major damage to corn, and reduces yield of food, feed, and biofuel materials. Transgenic hybrid corn expressing the Bacillus thuringiensis (Bt) toxin Cry1F is highly lethal to O. nubilalis larvae, thereby minimizing feeding damage. A laboratory colony of O. nubilalis was selected for increased Cry1F tolerance, which shows >12,000-fold compared to susceptible larvae and is capable of survival on transgenic hybrid corn. Genome linkage maps with segregating AFLP markers show that the Cry1F resistance trait is controlled by a single quantitative trait locus (QTL) on linkage group 12. The map position of five single nucleotide polymorphism (SNP) markers, inclusive of midgut Bt toxin receptor genes, alkaline phosphatase, aminopeptidase N, and cadherin, also were determined and shown not to be tightly linked or co-segregate with the Cry1F QTL. Evidence suggests that genes within this genome interval may give rise to a novel Bt toxin resistance trait for Lepidoptera. This information will be useful to scientists interested in delaying or preventing insect resistance to Bt crops.