Infection with toxigenic and atoxigenic strains of Aspergillus flavus induces different transcriptional signatures in maize kernels

The application of atoxigenic Aspergillus flavus strains in maize fields has been shown to be an effective\r\nstrategy for controlling contamination of aflatoxins, potent carcinogens produced by the fungus. This\r\nstudy monitored the expression levels of 18 defense genes against toxigenic and atoxigenic A. flavus\r\nstrains in developing maize kernels over a time course of 96 h after inoculation. A stronger\r\nupregulation of genes encoding pathogenesis-related proteins, oxidative stress-related proteins,\r\ntranscriptional factors and lipoxygenases were observed in response to the atoxigenic strain. On\r\nthe other side, this strain showed a significant enhanced growth in the later stages of infection,\r\nmeasured as copy number of the constitutive calmodulin gene. These results suggest that\r\noverexpression of maize-defense-associated genes observed in response to the atoxigenic strain\r\ncould contribute to an aflatoxin reduction. The identification of genes significantly affecting the\r\nresistance to A. flavus or aflatoxin accumulation would accelerate the development of resistant\r\ncultivars.