Submitted to: Aflatoxin Elimination Workshop Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 10/19/2007
Publication Date: 3/5/2008
Citation: Guo, B., Coy, A., Luo, M., Krakowsky, M.D., Abbas, H.K., Lee, D. 2007. Development of corn inbred lines with reduced preharvest aflatoxin contamination and identification of genes/markers for breeding and germplasm evaluation [abstract]. Proceedings of the 2007 Multicrop Aflatoxin/Fumonisin Elimination and Fungal Genomics Workshop, October 21-26, 2007, Atlanta, Georgia. p. 89.
Technical Abstract: Host plant resistance is a highly desirable tactic that can be used to manage aflatoxin contamination. Screening and identification of corn germplasm for resistant traits for crop improvement and molecular marker development will bring new genetic diversity into US corn germplasm. Using the combination of genetic and genomic approaches to elucidate crop defense pathways and understand the resistance mechanism and regulation will enhance genetic breeding for better crop with improved resistance. The field screening and evaluation of inbreds from different regions of the world in 2006 and 2007 have identified some lines with reduced aflatoxin contamination. Two inbred lines, GT601 (AM-1) and GT602 (AM-2), have been released. GT601 (AM-1) (PI 644026) and GT602 (AM-2) (PI 644027) are yellow dent maize (Zea mays L.) lines developed and released jointly by the USDA-ARS Crop Protection and Management Research Unit and the University of Georgia Coastal Plain Experiment Station in 2006. GT601 (AM-1) and GT602 (AM-2) were developed by seven generations of self-pollination from a maize population GT-MAS:gk (PI 561859). This population was derived from an older hybrid visibly segregating for fungal infection by Aspergillus flavus, and selected for resistance to the fungal infection and reduction of aflatoxin contamination. Maize line Tex6 was reported to have reduced aflatoxin contamination. By using maize 70-mer oligo-array, our goal was to study gene expression profiles in the kernels during late developmental stages in order to understand gene expression patterns of storage components, especially defense related genes. We analyzed temporal patterns of gene expression profiles in developing kernels at 25, 30, 35, 40 and 45 days after pollination (DAP) under normal irrigation or drought stressed condition. In comparison with 25 DAP, expression of 211 genes was significantly different at 45 DAP (P < 0.05), and 134 genes was up-regulated at normal irrigation condition. In contrast, under drought stressed condition we identified 154 defense-related genes expressed significantly (two fold change) from 35 DAP to 45 DAP, and 73 genes identified as down regulation are classified as disease resistance, stress response, and antioxidants. Further analysis will be conducted to compare these defense-related genes identified under normal irrigation or drought stressed condition, and will be used to screen more inbred lines.