Analysis of early gene expressed during colonisation of Aspergillus flavus in wild varieties and organic crops of Brazil nuts

• Grant number: 12/50075-4
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: October 01, 2012
• End date: January 31, 2016
• Field of knowledge: Agronomical Sciences - Food Science and Technology - Food Science
• Principal Investigator: Benedito Corrêa
• Grantee: Arianne Costa Baquião
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Brazil nut tree (Bertholletia excelsa Humb. & Bonpl., 1808 ), from Amazon rainforest, is important economically in the production of Brazil nuts, an seed with protein and energy value. There are two types of Brazil nut trees: 1- Native tree: Type "wild", coming from Amazon forest; 2- Cultivated and organic tree: Culture produced by grafting of selected genotypes by Embrapa and organic certification. The presence of aflatoxins is considered a difficulty in the export of Brazil nuts and Aspergillus flavus is the most important fungi associated with the production of aflatoxins in Brazil nuts. A. flavus is cosmopolitan, common in tropical countries, and their toxins are considered by International Agency for Research on Cancer, as highly carcinogenic to humans. Techniques based on molecular analysis have been successful in identifying fungal species and the detection of genes involved in biosynthesis of mycotoxins. The detection and quantification of the expression of regulatory genes involved the biosynthesis of mycotoxins are an important tool to studying the genetic capacity to produce different levels of mycotoxins by fungal species. Then, the analysis of gene expression may also contribute to the identification of factors that act in the production of aflatoxins. In this sense, the real-time PCR has been used because it ensures fast, high specificity, and quantification of gene expression analysis. However, there is no scientific report involving the expression of genes responsible for the biosynthetic pathway of aflatoxins in Brazil nuts. Considering these aspects, the aims of this work are: 1- Determine aflatoxigenic potential of 30 Aspergillus flavus strains isolated from Brazil nuts; 2- Check expression profile of 14 genes of A. flavus involved in biosynthesis and regulating of aflatoxins production, using technique of Real Time RT PCR, 3- Correlate the toxigenic potential and gene expression in each culture medium analysed, 4- Compare the results of aflatoxins production and gene espression between two types of Brazil nuts (native and cultivated). (AU)