ARS | Publication request: Aflatoxin Accumulation in BT and non-BT Maize Testcrosses

Submitted to: Journal of Crop Improvement
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 28, 2010
Publication Date: December 1, 2010
Citation: Williams, W.P., Windham, G.L., Krakowsky, M.D., Scully, B.T., Ni, X. 2010. Aflatoxin accumulation in BT and non-BT maize testcrosses. Journal of Crop Improvement. 24:392-399.

Interpretive Summary: The accumulation of aflatoxin, which is produced by the fungus, Aspergillus flavus, in corn is a major food and feed safety concern. Aflatoxin causes cancer in humans and is toxic to livestock, pets, and wildlife. The presence of aflatoxin in corn grain greatly diminishes its value and marketability. Growing corn hybrids with genetic resistance to aflatoxin accumulation is widely considered a desirable means of reducing aflatoxin contamination. Identifying corn germplasm with resistance is critical to the development and commercialization of such hybrids. Ten germplasm lines of corn with different levels of resistance to aflatoxin contamination were crossed with two proprietary germplasm lines that differed only in that one line was transformed to express a BT insecticidal protein found in the bacterium Bacillus thuringiensis. The resulting testcrosses were evaluated for aflatoxin accumulation. Aflatoxin accumulation was lower in the testcrosses with the BT line; however, the relative rankings of the ten germplasm lines were similar whether crossed to the BT or non-BT line. This information is useful for future germplasm screenings and development of corn hybrids with high levels of resistance to aflatoxin accumulation.

Technical Abstract: The accumulation of aflatoxin, which is produced by the fungus, Aspergillus flavus Link: Fries, in maize is a chronic problem in the southeastern United States. Its presence in grain greatly reduces its value and marketability. Aflatoxin accumulation is frequently associated with high temperatures, drought, and insect damage. Ten maize germplasm lines, some selected for resistance to aflatoxin accumulation, were crossed to transgenic [transformed with genes from Bacillus thuringiensis Berliner (BT) and expressing the Cry1Ab protein] and non-transgenic versions of LH287. Testcrosses were evaluated for ear damage from insect feeding and aflatoxin accumulation. Ear damage caused by insect feeding and aflatoxin accumulation were significantly less in BT than non-BT testcrosses. The germplasm line × BT/non-BT interaction was not significant. Lines selected for resistance to aflatoxin accumulation (Mp313E, Mp717, Mp04:97) exhibited the lowest levels of aflatoxin whether crossed to the BT or non-BT versions of LH287.