Submitted to: Toxins
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/19/2010
Publication Date: 4/26/2010
Citation: Brown, R.L., Chen, Z.-Y, Warburton, M., Luo, M., Menkir, A., Fakhoury, A., Bhatnagar, D. 2010. Discovery and Characterization of Proteins Associated with Aflatoxin-Resistance: Evaluating Their Potential as Breeding Markers. Toxins. 2(4):919-933. Interpretive Summary: The fungus named Aspergillus flavus produces a poison called aflatoxin when it infects corn kernels. Aflatoxin prevents the corn from being used commercially. The best strategy for controlling this problem is to develop corn that is resistant to aflatoxin contamination. Corn lines with natural resistance exist and others are being developed through breeding. To transfer resistance from these lines to ones of commercial value, breeding markers are needed. Towards this aim, a number of kernel resistance-associated proteins or RAPs and their corresponding genes have been identified by using proteomics to compare resistant with susceptible corn lines. These proteins comprise different functions: antifungal, stress-related, storage and possible regulatory functions. RAPs have also been further characterized by studies designed to determine their role in resistance to aflatoxin contamination and their potential as gene markers. Based on the information obtained there are several RAPs demonstrating potential to serve as markers in a marker assisted breeding strategy. Further studies are needed to determine their usefulness. Success could lead to the development of commercial lines with aflatoxin-resistance. This could result in future savings of millions of dollars to growers, due to the elimination of aflatoxin contamination of corn.
Technical Abstract: Host resistance has become a viable approach to eliminating aflatoxin contamination of maize since the discovery of several maize lines with natural resistance. However, to derive commercial benefit from this resistance and develop lines that can aid growers, markers need to be identified to facilitate the transfer of resistance into commercially useful genetic backgrounds without transfer of unwanted traits. To accomplish this, research efforts have focused on the identification of kernel resistance-associated proteins (RAPs) including the employment of comparative proteomics to investigate near-isogenic maize lines that vary in aflatoxin accumulation. RAPs have been identified and several further characterized through physiological and biochemical investigations to determine their causal role in resistance and, therefore, their suitability as breeding markers. Three RAPs, a 14 kDa trypsin inhibitor, pathogenesis-related protein 10 and glyoxalase I are being investigated using RNAi gene silencing and plant transformation. Several resistant lines have been subjected to QTL mapping to identify loci associated with the aflatoxin-resistance phenotype. Results of proteome and characterization studies are discussed.