Submitted to: Journal of Toxicology and Applied Pharmacology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2003
Publication Date: 8/1/2003
Citation: WILLIAMS, W.P., WINDHAM, G.L., BUCKLEY, P.M. ENHANCING MAIZE GERMPLASM WITH RESISTANCE TO AFLATOXIN CONTAMINATION. JOURNAL OF TOXICOLOGY TOXIN REVIEWS.2003. V.22.P.175-193. Interpretive Summary: Aflatoxin contamination is a major impediment to profitable corn production in the South. The presence of aflatoxin, a potent carcinogen produced by the fungus Aspergillus flavus, at levels exceeding 20 parts per billion restricts corn grain from interstate commerce. Growing hybrids with genetic resistance is generally considered the best way to reduce aflatoxin contamination of corn. USDA-ARS scientists at Mississippi State initiated research in the 1970s to identify and develop germplasm lines with resistance to aflatoxin contamination. The release of Mp313E, a line developed from 'Tuxpan', in 1988 marked the first release of an aflatoxin resistant germplasm line. A second line, Mp420, was released in 1991. Mp715 was released in 1999. In an experiment conducted in 2001, aflatoxin contamination for Mp715 was only 14 parts per billion compared to 9289 parts per billion for SC212M, a susceptible line. When used in crosses with other lines, the aflatoxin-resistant lines markedly reduce the levels of aflatoxin contamination in the resulting hybrids. Additional germplasm is being screened to identify new sources of resistance. These lines can be used in developing high yielding corn hybrids that have resistance to aflatoxin contamination.
Technical Abstract: Preharvest kernel infection by Aspergillus flavus and the subsequent accumulation of aflatoxin in maize grain are chronic problems in the southeastern United States. Aflatoxin is a natural carcinogen, and its presence markedly reduces the value of grain. Losses to aflatoxin contamination reach devastating levels some years. Development and deployment of maize hybrids with resistance to aflatoxin contamination is generally considered the most feasible method of reducing or eliminating the problem. Research to address the aflatoxin problem was initiated by USDA-ARS at Mississippi State, MS, in the late 1970s. The goals of the research were to identify and develop aflatoxin-resistant maize germplasm. First, reliable techniques for screening germplasm were developed. Then, germplasm from numerous sources was screened. The release of Mp313E in 1988 was the first release of maize germplasm with resistance to aflatoxin contamination. Two other germplasm lines, Mp420 and Mp715, were released in 1991 and 1999, respectively. Additional germplasm lines have been developed, but not yet released. Efforts are currently underway to identify other sources of resistance. When used in crosses with other lines, the aflatoxin-resistant lines markedly reduce the level of aflatoxin contamination in the resulting hybrids. Analysis of a diallel cross indicated that general combining ability was a significant source of variation in the inheritance of resistance to aflatoxin contamination. Efforts to combine resistance to aflatoxin combination and agronomic qualities using both conventional breeding methods and molecular marker assisted selection have been initiated.