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Identification of Unique or Elevated Levels of Kernel Proteins in Aflatoxin-Resistant Maize Genotypes Through Proteome Analysis

October 2002 , Volume 92 , Number  10
Pages  1,084 - 1,094

Z.-Y. Chen , R. L. Brown , K. E. Damann , and T. E. Cleveland

First and third authors: Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge 70803; and second and fourth authors: Southern Regional Research Center, USDA-ARS, New Orleans, LA 70179

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Accepted for publication 14 June 2002.

Aflatoxins are carcinogens produced by Aspergillus flavus and A. parasiticus during infection of susceptible crops such as maize (Zea mays L.). Resistant maize genotypes have been identified, but the incorporation of resistance into commercial lines has been slow due to the lack of selectable markers. Here we report the identification of potential markers in resistant maize lines using a proteomics approach. Kernel embryo proteins from each of two resistant genotypes have been compared with those from a composite of five susceptible genotypes using large format two-dimensional gel electrophoresis. Through these comparisons, both quantitative and qualitative differences have been identified. Protein spots have been sequenced, and based on peptide sequence homology analysis, are categorized as follows: storage proteins (globulin 1 and globulin 2), late embryogenesis abundant (LEA) proteins related to drought or desiccation (LEA3 and LEA14), water- or osmo-stress related proteins (WSI18 and aldose reductase), and heat-stress related proteins (HSP16.9). Aldose reductase activity measured in resistant and susceptible genotypes before and after infection suggests the importance of constitutive levels of this enzyme to resistance. Results of this study point to a correlation between host resistance and stress tolerance. The putative function of each identified protein is discussed.

Additional keywords: host resistance, resistance-associated proteins.

The American Phytopathological Society, 2002