Prevalence of NRRL21882-like (Afla-Guard(R))Aspergillus flavuson sesame seeds grown in research fields in the Mississippi Delta

摘要

A collection of 500Aspergillus flavusisolates from four sesame varieties (S-34, S-35, S-38, and S-39) that were planted in field plots in the Mississippi Delta and in the Florida Panhandle were investigated because of low-level aflatoxin contamination detected in sesame seeds. A rapid molecular fingerprinting method was developed to assess the influence of prior applications of the atoxigenic Afla-Guard(R)biocontrol product whose active strain is NRRL21882 on theA. flavuspopulations within each field plot. Depending on sesame seed sampled, 66.7% to 95.9% ofA. flavusisolates from Mississippi belonged to the NRRL21882 genotype, which lacks the aflatoxin and cyclopiazonic acid biosynthesis gene clusters. In contrast, only 5.0% to 32.5% of the isolates from Florida had lost both gene clusters. The high incidence of NRRL21882-likeA. flavusin Mississippi sesame samples can be attributed to prior applications of Afla-Guard(R)in that local area. The results suggest the adaptability of this particular type of atoxigenicA. flavusbiocontrol strain in the field.