Wednesday, November 15, 2006 - 8:15 AM

Aflatoxin Accumulation in Maize with Different Isolates of Aspergillus flavus.

Kerry L. Mayfield1, T. Isakeit2, Gary Odvody3, and F. J. Betran1. (1) Texas A&M Univ, Soil and Crop Sciences, College Station, TX 77843-2474, (2) Texas A&M, College Station, TX 77845, (3) Texas Agricultural Experiment Station, 10345 Agnes, Corpus Christi, TX 78406

Screening for aflatoxin resistance is conducted in the field under inoculation with Aspergillus flavus, commonly with one isolate (NRRL3357).  Our objective was to determine if there is interaction between genetically-different isolates of A. flavus and several genotypes of maize.  Two experiments, one with hybrids and one with inbreds, were conducted at three Texas locations in 2004 and 2005. Inbreds and hybrids were selected for maturity and previous response to aflatoxin.  Genotypes were inoculated using the silk channel inoculation method using isolates L1, F1, I5 (isolated from soil in a maize field in San Patricio County, Texas) and NRRL3357.  Different plants within the same row were inoculated with the different isolates.  Plants inoculated with the different isolates were identified using colored tape.  Plots were hand harvested, shelled and ground prior to quantification of AF using Vicam AflatestTM.  Significant differences for aflatoxin among genotypes and isolates were detected in both trials (inbreds and hybrids).  Isolates I5 and F1 produced more aflatoxin in genotypes than commonly used NRRL3357.  Genotype*isolate interaction was non significant for any location, and neither trial (hybrids and inbreds).  One isolate of A. flavus may be used in screening for resistance, however; results may be limited in years that are unfavorable for that isolate.