Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2005
Publication Date: 4/30/2005
Citation: Dowd, P.F., Johnson, E.T. 2005. Association of a specific cationic peroxidase isozyme with maize stress and disease resistance responses, genetic identification and identification of a cDNA coding for the isozyme. Journal of Agricultural and Food Chemistry 53(11):4464-4470. Interpretive Summary: Fungal toxins (mycotoxins) in corn cause hundreds of millions of dollars in losses each year. Both insects and fungi contribute to the problem. A protein was identified that is associated with fungal resistance in several corn lines tested, and that also occurred in insect resistant material. A cDNA clone that produced the protein was also identified. Incorporation of the gene that produces the protein into corn through breeding or genetic engineering may result in more resistant material that accumulates lower levels of mycotoxins, thereby providing safer food for animals and people.
Technical Abstract: The presence of a pI 9.0 cationic peroxidase isozyme from milk stage pericarp of six susceptible and five resistant inbreds was correlated significantly with previously reported field data on percentage infection by Aspergillus flavus in the inbreds and their hybrids. The isozyme was constitutively expressed in some additional maize tissues and lines examined, and frequently induced by mechanical damage, heat shock, Fusarium proliferatum, and/or Bacillus subtilis in other lines tested. Native/IEF 2D electrophoresis identified the isozyme as the previously genetically identified px5. A cDNA clone expressed in black Mexican sweet (BMS) maize cell cultures produced the pI 9.0 isozyme. In addition to potential use in marker assisted breeding, enhanced expression of this cationic peroxidase through breeding or genetic engineering may lead to enhanced disease or insect resistance.