Submitted to: Aflatoxin Elimination Workshop Proceedings
Publication Type: Abstract only
Publication Acceptance Date: 10/28/2005
Publication Date: 4/1/2006
Citation: Guo, B., Lee, D., Xu, W., Davis, D., Luo, M. 2006. Quantitative expression analysis of adversity resistance genes in corn germplasm with resistance to preharvest aflatoxin contamination [abstract]. Proceedings of the 18th Annual Multi-Crop Aflatoxin Elimination Workshop, October 24-26, 2005, Raleigh, North Carolina. p. 86. Interpretive Summary:
Technical Abstract: Aflatoxin contamination of corn in the field is known to be influenced by numerous factors. Drought stress is conducive to Aspergillus flavus infection and aflatoxin accumulation. Drought tolerant germplasm could reduce preharvest aflatoxin contamination. The goals of this project are to understand the changes of gene expression in response to drought stress using maize microarray and to identify the biochemical pathways and important genes associated with resistance to A. flavus and drought tolerance. In this report, we are reporting the development of a set of gene/probes in assessment of maize germplasm with drought tolerance and A. flavus resistance. In our 2004 maize microarray study, we found the quantitative difference in gene expression under drought stress, and the resistance by induction using BTH was not significantly improved. Based on the gene expression analysis and reported data, we selected 119 genes, including two reference genes, with adversity resistance to test gene differential expression in six maize lines, A638, B73, LO1016, LO964, MO17 and Tex6, using real-time RT-PCR. The drought stress was applied at 25DAP (day after pollination) for stressed plots. Corn ears at 35 DAP were harvested and only kernels were used for gene expression analysis in response to drought stress using the designed primers. We are interested in the genes related with adversity resistance, particularly drought tolerance and fungal resistance. Microarray is a powerful tool to select important genes in response to abiotic and biotic stresses. For the last two years, we have been using maize microarray in searching for genes/pathways associated with these two traits and we found that the differential expressions of the majority genes are quantitative. The real-time RT-PCR data of the selected genes indicate that the repeatability of this method is high. The genes related with signal pathways had high C(T) cycles, and 86 genes had detectable and repeatable changes in response to drought stress or among the selected maize lines. A638, TEX6 and LO964 had more up-regulated genes in comparison with B73. If B73, LO1016 and MO17 were used as reference lines, respectively, there were 10 cross-talking positive genes which can be selected from A638, TEX6 and LO964. These genes are related with drought response and disease resistance.