GENETIC AND GENOMIC APPROACHES TO IMPROVE PEANUT AND CORN RESISTANCE TO DISEASE AND AFLATOXIN CONTAMINATION
Location: Crop Protection and Management Research
Title: Gene expression profiling and identification of resistance genes to aspergillus flavus infection in peanut through EST and microarray strategies.
Submitted to: Toxins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 28, 2011
Publication Date: December 20, 2011
Citation: Guo, B., Fedorova, N.D., Chen, X., Wan, C., Wang, W., Nierman, W., Bhatnagar, D., Yu, J. 2011. Gene expression profiling and identification of resistance genes to aspergillus flavus infection in peanut through EST and microarray strategies. Toxins. 3:737-753.
Interpretive Summary: Peanut has been an important food and oil crop, containing not only a high percentage of oil (about 50%) but also contains a high quality unsaturated fatty acid (oleic acid). World peanut production occupies an important role in the world economy. With the increased awareness of aflatoxin contamination in peanut, the presence of aflatoxin in peanut products has become a serious food safety concern to human health. Understanding peanut-fungus interactions during the growth of both the peanut crop and the fungus is necessary to develop effective strategies to reduce or eliminate aflatoxin contamination. Currently, peanut cultivars that are resistant to A. flavus and A. parasiticus infection are rare, and little is known about the molecular mechanisms that confer such resistance. To gain a better understanding of these mechanisms, we recently developed and tested the utility of the first large-scale peanut microarray, investigating the gene expression in different peanut tissues. Subsequently, as part of U.S. Peanut Genome Initiative supported by U.S. Industry and Peanut Growers, our group developed a large scale peanut EST project for the cultivated peanut and provided the genomic resources for use in marker development and gene discovery. Here we report the development of a peanut microarray based on these EST sequences as well as other publicly available peanut EST sequences. We employed this array in gene expression profiling experiments to identify candidate genes that confer resistance to Aspergillus infection due to up-expression in response to fungal infection using a resistant peanut line in comparison with a susceptible line. This study is a first step towards a comprehensive genome-scale platform for developing Aspergillus-resistant peanut cultivars.
Aspergillus flavus and A. parasiticus infect peanut seeds and produce aflatoxins, which are associated with various diseases in domestic animals and humans throughout the world. The most cost-effective strategy to minimize aflatoxin contamination involves the development of peanut cultivars that are resistant to fungal infection and/or aflatoxin production. To identify peanut Aspergillus-interactive and peanut Aspergillus-resistance genes, we carried out a large scale peanut Expressed Sequence Tag (EST) project which we used to construct a peanut glass slide oligonucleotide microarray. The fabricated microarray represents over 40% of the protein coding genes in the peanut genome. For expression profiling, resistant and susceptible peanut cultivars were infected with a mixture of Aspergillus flavus and parasiticus spores. The subsequent microarray analysis identified 62 genes in resistant cultivars that were up-expressed in response to Aspergillus infection. In addition, we identified 22 putative Aspergillus-resistance genes that were constitutively up-expressed in the resistant cultivar in comparison to the susceptible cultivar. Some of these genes were homologous to peanut, corn, and soybean genes that were previously shown to confer resistance to fungal infection. This study is a first step towards a comprehensive genome-scale platform for developing Aspergillus-resistant peanut cultivars through targeted marker-assisted breeding and genetic engineering