Submitted to: Journal of Integrative Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/19/2008
Publication Date: 10/13/2008
Citation: Guo, B., Chen, Z., Lee R.D., Scully B.T. 2008. Drought stress and preharvest aflatoxin contamination in agricultural commodity: Genetics, genomics and proteomics. Journal of Integrative Plant Biology. 50(10):1281-1291.
Interpretive Summary: Aflatoxin contamination is considered one of the most serious food safety issues concerning human health worldwide. Chronic problems with preharvest aflatoxin contamination occur in the southern crops, corn, peanut, cottonseed, and tree nuts. Drought stress is a major contributor to preharvest aflatoxin contamination. Research experiments have demonstrated that higher levels of plant defense- or stress-related chemicals occurred in corn seeds of resistant varieties compared with susceptible ones, suggesting that field condition (drought stress or no stress) influences the production of these chemical compounds differently in different corn varieties. Because of the complexity of the toxin-producing fungus and plant interactions, biotechnology of genomics and proteomics will help the understanding of the genetic resistance mechanisms in the affected commodities by aflatoxin. Genetic improvement of crop resistance to drought stress is one component and will provide a good perspective on the efficacy of control strategy.
Technical Abstract: Throughout the world, aflatoxin contamination is considered one of the most serious food safety issues concerning health. Chronic problems with preharvest aflatoxin contamination occur in the southern US, and are particularly troublesome in corn, peanut, cottonseed, and tree nuts. Drought stress is a major factor to contribute to preharvest aflatoxin contamination. Recent studies have demonstrated higher concentration of defense or stress-related proteins in corn kernels of resistant genotypes compared with susceptible genotypes, suggesting that preharvest field condition (drought or not drought) influences gene expression differently in different genotypes resulting in different levels of “end products"--PR-proteins in the mature kernels. Because of the complexity of Aspergillus-plant interactions, better understanding of the mechanisms of genetic resistance will be needed using genomics and proteomics for crop improvement. Genetic improvement of crop resistance to drought stress is one component and will provide a good perspective on the efficacy of control strategy. Proteomic comparisons of corn kernel proteins between resistant or susceptible genotypes to A. flavus infection have identified stress-related proteins along with antifungal proteins as associated with kernel resistance. Gene expression studies in corn developing kernels are in agreement with the proteomic studies that defense-related genes could be up- or down-regulated by abiotic stresses.