Renee S Arias
USDA-Agricultural Research Service, USA
Title: Host-Induced Gene Silencing (HIGS) of aflatoxin synthesis genes in peanut and maize: Use of RNA interference and genetic diversity of Aspergillus
Biography
Biography: Renee S Arias
Abstract
Approximately 4.5 billion people are chronically exposed to aflatoxins, these are powerful carcinogens produced by Aspergillus flavus and A. parasiticus. High levels of aflatoxins in crops result in approximately 100 million metric tons of cereals, nuts, root crops and other agricultural products being destroyed or diverted to non-human consumption each year. We have targeted silencing of 5-genes in the aflatoxin biosynthesis pathway of Aspergillus by RNA interference (RNAi) from the plant host to reduce/eliminate aflatoxin accumulation in peanut and maize seeds. Given that no method existed to analyze the effectiveness of RNAi against aflatoxins, and that testing of hundreds of plants in the field under aflatoxin-conducive conditions is not an option in this case, we developed a method of challenging with aflatoxigenic Aspergillus the RNAi treated seeds, and then analyze those seeds by ultra-performance liquid chromatography (UPLC). In parallel, we developed a workflow to obtain information of those isolates at the DNA sequencing level. This workflow includes fungal isolation, 25 InDel fingerprinting followed by cluster analysis, and whole genome sequencing of clade representatives. This method also allows analysis of small seed pieces for gene expression by real-time PCR (RT-PCR) and small RNA sequencing. Solving the aflatoxin problem in crops would be equivalent to increasing food production by millions of tons that could be safely consumed instead of being discarded or diverted to other uses.