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United States Department of Agriculture

Agricultural Research Service

Research Project: ENHANCING CORN WITH RESISTANCE TO AFLATOXIN CONTAMINATION AND INSECT DAMAGE Title: Identification of maize genes associated with host plant resistance and susceptibility to Aspergillus flavus infection and aflatoxin accumulation

Authors
item Kelley, Rowena -
item Williams, William
item Mylroie, John
item Boykin, Deborah
item Harper, John -
item Windham, Gary
item Ankala, Arunkanth -
item Shan, Xueyan -

Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 14, 2012
Publication Date: May 14, 2012
Citation: Kelley, R.Y., Williams, W.P., Mylroie, J.E., Boykin, D.L., Harper, J.W., Windham, G.L., Ankala, A., Shan, X. 2012. Identification of maize genes associated with host plant resistance and susceptibility to Aspergillus flavus infection and aflatoxin accumulation. PLoS One. 7:1-12. doi:10.1371/journal.pone.0036892

Interpretive Summary: Contamination of corn grain with aflatoxin, which is produced by the fungus Aspergillus flavus, is a serious threat to food and feed safety. It impedes profitable corn production in many areas including the southern United States. Growing corn hybrids with genetic resistance to A. flavus infection and aflatoxin accumulation is widely considered a desirable way to reduce aflatoxin contamination of corn grain. This study was conducted to identify genes in corn associated with resistance to aflatoxin accumulation that could be used to transfer genetic resistance into susceptible, but otherwise desirable, corn hybrids. Thirty-one genes associated with resistance and susceptibility were identified using microarray analysis, quantitative real-time polymerase chain reaction (qRT-PCR) analysis, and quantitative trait loci (QTL) analysis. These will be used to identify molecular markers for use in corn breeding programs developing corn hybrids with genetic resistance to aflatoxin contamination

Technical Abstract: Aspergillus flavus infection and aflatoxin contamination of maize pose negative impacts in agriculture and health. Commercial maize hybrids are generally susceptible to this fungus. Significant levels of host plant resistance have been observed in certain maize inbred lines. This study was conducted to identify maize genes associated with host plant resistance and susceptibility to A. flavus infection and aflatoxin accumulation. Genome wide gene expression levels with or without A. flavus inoculation were compared in two resistant maize inbred lines (Mp313E and Mp04:86) in contrast to two susceptible maize inbred lines (Va35 and B73) by microarray analysis. Principal component analysis (PCA) was used to find genes contributing to the larger variances associated with the resistant and susceptible maize inbred lines, respectively. The significance levels of gene expression were determined by using SAS and LIMMA programs. Fifty candidate genes were selected and further investigated by quantitative RT-PCR (qRT-PCR) in a time-course study on Mp313E and Va35. Sixteen of the candidate genes were found to be highly expressed in Mp313E and fifteen in Va35. Out of the 31 highly expressed genes, eight were mapped to seven previously identified quantitative trait locus (QTL) regions. A gene encoding glycine-rich RNA binding protein 2 was found to be associated with the host hypersensitivity and susceptibility in Va35. A nuclear pore complex protein YUP85-like gene was found to be involved in the host resistance in Mp313E. Maize genes associated with host plant resistance and susceptibility were identified by a combination of microarray analysis, qRT-PCR analysis, and QTL mapping methods. Our findings suggest that multiple mechanisms are involved in maize host plant defense systems in response to Aspergillus flavus infection and aflatoxin accumulation. These findings will be important in identification of DNA markers for breeding maize lines resistant to aflatoxin accumulation.

Last Modified: 12/18/2014