Submitted to: International Congress of Plant Pathology Abstracts and Proceedings
Publication Type: Proceedings
Publication Acceptance Date: September 25, 2002
Publication Date: February 2, 2003
Citation: ABBAS, H.K., ZABLOTOWICZ, R.M., BRUNS, H.A. 2003. NON-TOXIGENIC ASPERGILLUS FLAVUS ISOLATES FOR REDUCING AFLATOXIN IN MISSISSIPPI DELTA CORN. INTERNATIONAL CONGRESS OF PLANT PATHOLOGY ABSTRACTS AND PROCEEDINGS. Vol. 2:43. Technical Abstract: The potential for two non-toxigenic isolates of Aspergillus flavus CT3 and K49 isolated from the Mississippi Delta to reduce aflatoxin contamination of corn was assessed in a field study. These two isolates exhibited comparable growth and aggressiveness as the toxigenic A. flavus isolate F3W4. The two non-toxigenic isolates did not produce aflatoxins or cyclopiazonic acid (CPS) in culture or when grown on various substrates as analyzed by HPLC, TLC, LC-MS, and ELISA or cultural techniques (fluorescence or ammonia vapor assay). In 2001 a six treatment field study using a commercial corn hybrid consisting of the control (autoclaved wheat) and five wheat-based inoculants (the toxigenic isolate F3W4, two non-toxigenic isolates CT3 and K49, and two mixtures of the non-toxigenic isolates with F3W4) was established as a randomized complete block design of four replicates. Inoculum consisted of the fungi fermented on autoclaved wheat for 48 hrs at 30C applied at a rate of 20 kg ha-1 at the V 5 - 6 leaf stage of development. Initial field results in 2001 indicated that inoculation with the toxigenic isolate increased aflatoxin contamination of corn by 167% (or 662 ppb) compared to the non-inoculated control (223 ppb). The two non-toxigenic isolates caused dramatic reduction in aflatoxin contamination in corn kernels [CT3 and K49 reduced aflatoxin levels by 86% (or 32 ppb) and 60% (or 94 ppb), respectively]. Mixtures of toxigenic and non-toxigenic isolates had little effect on aflatoxin levels. The results of the same experiment in 2002 will be discussed as well. These results showed that indigenous non-toxigenic isolates of A. flavus have potential as biocontrol agents to reduce aflatoxin contamination in Mississippi Delta corn.