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United States Department of Agriculture

Agricultural Research Service

Title: Comparison of Kernel Wax from Corn Genotypes Resistant Or Susceptible to Aspergillus Flavus

Authors
item Russin, J. - LOUISIANA STATE UNIV.
item Guo, Baozhu
item Tubajika, K. - LOUISIANA STATE UNIV.
item Brown, Robert
item Cleveland, Thomas
item Widstrom, Neil

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 31, 1997
Publication Date: N/A

Interpretive Summary: A poisonous compound produced by the fungus Aspergillus flavus is a serious problem of contamination of food and feeds that threatens human and animal health. Developing strategies to reduce or eliminate aflatoxin contamination has become a priority in recent years. Our efforts have focused on enhancing host resistance to aflatoxin contamination. This study examined and compared kernel wax from our resistant line with that from kernels of several susceptible commercial hybrids. The resistant line had more pericarp wax than did the susceptible hybrids. Scanning electron microscopy revealed that kernels of this resistant line appeared rough and showed wax deposits that were abundant on kernel surfaces. Susceptible kernels appeared much more smooth and lacked the abundant surface deposits. In vitro bioassays showed that kernel wax reduced A. flavus colony diameter. Thin layer chromatography and computer image showed a distinctive composition for kernel wax of this resistant line. This represents the first report of specific kernel factors involved in resistance to A. flavus in corn and will be incorporated into our breeding program or used as a marker by breeders.

Technical Abstract: Kernels of corn genotype GT-MAS:gk are resistant to Aspergillus flavus. Earlier studies showed that this resistance was due in part to kernel pericarp wax. Experiments compared wax from GT-MAS:gk kerne th that from kernels of several susceptible commercial hybrids. GT-MAS:gk had more pericarp wax than did the susceptible hybrids. Scanning electron microscopy revealed that GT-MAS:gk kernels appeared rough and showed wax deposits that were abundant on kernel surfaces. Susceptible kernels appeared much more smooth and lacked the abundant surface deposits observed on GT-MAS:gk. In vitro bioassays showed that kernel wax from GT-MAS:gk reduced A. flavus colony diameter 35%. Colony diameters on medium amended with wax from susceptible kernels did not differ from controls. Thin layer chromatography and analyses of chromatograms using NIH Image software showed a distinctive composition for GT-MAS:gk kernel wax. This wax contained a peak unique to this genotype but also lacked a peak common to all susceptible hybrids. This represents the first report of specific kernel factors involved in resistance to A. flavus in corn.

Last Modified: 4/21/2014
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