Regional Differences in Production of Aflatoxin B1 and Cyclopiazonic Acid by Soil Isolates of Aspergillus flavus along a Transect within the United States

Horn, B. W. and Dorner, J. W. (1999) Regional Differences in Production of Aflatoxin B1 and Cyclopiazonic Acid by Soil Isolates of Aspergillus flavus along a Transect within the United States. Applied And Environmental Microbiology, 65 (4). pp. 1444-1449.

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Abstract

Soil isolates of Aspergillus flavus from a transect extending from eastern New Mexico through Georgia to eastern Virginia were examined for production of aflatoxin B1 and cyclopiazonic acid in a liquid medium. Peanut fields from major peanut-growing regions (western Texas; central Texas; Georgia and Alabama; and Virginia and North Carolina) were sampled, and fields with other crops were sampled in regions where peanuts are not commonly grown. The A. flavus isolates were identified as members of either the L strain (n 5 774), which produces sclerotia that are >400 mm in diameter, or the S strain (n 5 309), which produces numerous small sclerotia that are <400 mm in diameter. The S-strain isolates generally produced high levels of aflatoxin B1, whereas the L-strain isolates were more variable in aflatoxin production; variation in cyclopiazonic acid production also was greater in the L strain than in the S strain. There was a positive correlation between aflatoxin B1 production and cyclopiazonic acid production in both strains, although 12% of the L-strain isolates produced only cyclopiazonic acid. Significant differences in production of aflatoxin B1 and cyclopiazonic acid by the L-strain isolates were detected among regions. In the western half of Texas and the peanut-growing region of Georgia and Alabama, 62 to 94% of the isolates produced >10 mg of aflatoxin B1 per ml. The percentages of isolates producing >10 mg of aflatoxin B1 per ml ranged from 0 to 52% in the remaining regions of the transect; other isolates were often nonaflatoxigenic. A total of 53 of the 126 L-strain isolates that did not produce aflatoxin B1 or cyclopiazonic acid were placed in 17 vegetative compatibility groups. Several of these groups contained isolates from widely separated regions of the transect.

Item Type: Article
Additional Information: We thank R. Larry Greene for technical assistance and Milbra Schweikert for assistance with the mycotoxin analyses.
Author Affiliation: National Peanut Research Laboratory, U.S. Department of Agriculture, Agricultural Research Service, Dawson, Georgia 31742
Subjects: Crop Improvement
Divisions: General
Depositing User: Mr Siva Shankar
Date Deposited: 23 May 2012 10:31
Last Modified: 23 May 2012 10:31
URI: http://eprints.icrisat.ac.in/id/eprint/5677

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