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United States Department of Agriculture

Agricultural Research Service

Title: Germination Induces Accumulation of Specific Proteins and Antifungal Activities in Corn Kernels

Authors
item Guo, Baozhu
item Brown, Robert
item Lax, Alan
item Cleveland, Thomas
item Russin, J. - LOUISIANA STATE UNIV.
item Mehta, A. - NORTH CAROLINA STATE UNIV
item Selitrennikoff, C. - UNIV COLORADO HEALTH SERV
item Widstrom, Neil

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 25, 1997
Publication Date: N/A

Interpretive Summary: Contamination of food and feeds made from corn contaminated with aflatoxin, a poisonous compound produced by the fungus Aspergillus flavus, is a problem 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 protein induction and accumu- lation during germination of corn kernels and the antifungal activities of extracts from germinated kernels against Aspergillus flavus and Fusarium moniliforme. Five protein bands were present at higher concentrations in germinated kernels than in non-germinated kernels. One protein reacted with zeamatin antiserum and accumulated to a higher concentration in germinated kernels. Two protein bands from dry kernels which reacted with ribosome- inactivating-protein (RIP) antiserum as an inactive form. In germinated kernels, 2 protein bands which reacted with RIP antiserum were identified as the 2 active peptides. Bioassays of germinated kernel extracts from all 4 genotypes exhibited antifungal activity against A. flavus and F. moniliforme, with extracts from the susceptible genotypes showing greater inhibition zones. This study provides evidence of protein induction in corn kernels during the early stages of germination. This finding may result in the production of transgenic plants with desired resistance to Aspergillus, Fusarium, and mycotoxin production.

Technical Abstract: This study examined protein induction and accumulation during imbibition and germination of corn kernels as well as antifungal activities of extracts from germinating kernels against Aspergillus flavus and Fusarium moniliforme. Genotypes studied were GT-MAS:gk and Mp420, resistant to A. flavus infection and aflatoxin accumulation, and susceptible Pioneer 3154 and Deltapine G-4666. SDS-PAGE resolved 5 protein bands that were present at higher concentrations in germinated kernels than in non-germinated kernels. Western blot analyses revealed that one of these proteins reacted with the 22 kDa zeamatin antiserum and accumulated to a higher concentration in germinated kernels. Two protein bands from dry kernels which reacted with ribosome- inactivating-protein (RIP) antiserum were identified as the 32 kDa proRIP form and one 18 kDa of the 2 peptides that form active RIP. However, in germinated kernels, 2 protein bands which reacted with RIP antiserum were identified as the 2 peptides of molecular weight about 18 kDa and 9 kDa, respectively. Bioassays of germinated kernel extracts from all 4 genotypes exhibited antifungal activity against A. flavus and F. moniliforme, with extracts from the susceptible genotypes showing greater inhibition zones. This study provides evidence of protein induction in corn kernels during imbibition or the early stages of germination and the induced proteins may be related to our previous findings of germination-associated resistance in the corn kernel, especially in the susceptible kernels.

Last Modified: 12/18/2014
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