Resumo

Maize is the third most cultivated crop worldwide, and Brazil is currently, the fourth largest producer in the world. Fusarium verticillioides is commonly associated with maize and it is capable to produce high levels of fumonisins. Studies regarding the use of transgenic corn have shown that fumonisin contamination could be reduced due to the damage decrease caused by insects on grains. The aim of this study was to evaluate the effect of cry 1F toxin produced by Bacillus thuringiensis subsp. aizawai, expressed in the 2B710Hx (Herculex) corn hybrid on the fumonisin production and on FUM gene expression by F. verticillioides ICB 13BA (NCBI accession number; GU 989110). 2B710 Hx corn samples and its respective isogenic non-Bt were previously irradiated with 20 kGy in order to eliminate fungi contaminants from field. Plates were inoculated with 5 x 108 spores/mL and incubated at 25 oC and Aw of 0.99. After 10, 20 and 30 days, samples were analysed regarding FB1 and FB2 contamination and FUM1, FUM3, FUM6, FUM7, FUM8, FUM10, FUM11, FUM13, FUM14, FUM15, FUM17, FUM18, FUM19 and FUM21 gene expression. The statistical analyses were performed using the softwares R 2.9, Gamlss package and SAS 9.1. The results showed reduced fumonisin B1 contamination on 2B710 Hx during the 30 days of analyses (p< 0.005). Regarding FB2, there was no statistical difference between the isogenic and transgenic hybrids. There was no correlation between FUM gene cluster and fumonisin production according to Pearson’s correlation test (except for FUM19, p<0.005), nevertheless, FUM genes were, in general, less expressed on 2B710Hx as demonstrated by Mann-Whitney test (p<0.04). It is essential to perform more tests regarding the interaction between Bt proteins and Fusarium in order to contribute to fumonisin management.