Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 17, 2001
Publication Date: February 1, 2002
Interpretive Summary: Aflatoxin contamination of corn grain is a major problem for growers in the southeastern United States. This toxin is most commonly found in corn grown under high temperatures and drought conditions. Very few control strategies are available for growers to use to limit toxin development. One of the better methods of control is the use of resistance to aflatoxin contamination. Unfortunately, no commercial corn hybrids are available with resistance. This study was initiated to identify new sources of resistance to aflatoxin contamination. Seventy- eight corn inbred lines and advanced breeding lines were evaluated in five tests over three years for aflatoxin contamination. Ears were artificially inoculated with Aspergillus flavus, the fungus that produces aflatoxin in the grain. At harvest, grain was dried, ground, and aflatoxin levels determined. Aflatoxin levels were extremely high in 1998 which was the same year a major aflatoxin epidemic occurred in Southeast. In 1999 and 2000, more moderate aflatoxin levels were observed. Several lines that exhibited resistance to aflatoxin in some of the tests will be further evaluated in other environments. These lines provide potential new sources of resistance for developing aflatoxin resistant corn hybrids.
Technical Abstract: Seventy-eight corn inbred lines and advanced breeding lines were evaluated for resistance to aflatoxin contamination when artificially inoculated with Aspergillus flavus in 1998, 1999 (two tests), and 2000 (two tests) at Mississippi State, MS. The top ear of each plant was inoculated with the A. flavus isolate using the side-needle technique. Ears were harvested ca. 63 days after midsilk and aflatoxin contamination was determined using the Vicam AflaTest. Aflatoxin contamination in the inbreds was extremely high in 1998. Levels ranged from 139 to 21,090 ng/g. High ambient temperatures during silking may have contributed to these high aflatoxin levels. In 1999 under more moderate temperatures, aflatoxin contamination ranged from 14 to 1,278 ng/g in one test and 17 to 1,070 ng/g in another test. In 2000, aflatoxin levels ranged from 227 to 7,503 ng/g in one test and from 209 - 2,565 ng/g in another test. Several lines exhibited high levels of resistance to aflatoxin contamination. These lines will be evaluated further. They provide potential new sources of resistance which may be useful in moving aflatoxin resistance into commercial corn hybrids.