Host-induced gene silencing targeting the Aspergillus flavus omtA gene to reduce aflatoxin contamination in maize    
Y. RARUANG (1), O. Omolehin (2), Q. Wei (3), R. Brown (4), D. Bhatnagar (3), Z. Chen (2) (1) Louisiana State Univeristy AgCenter, U.S.A.; (2) Louisiana State University AgCenter, U.S.A.; (3) United States Department of Agriculture Agricultural Research Service, U.S.A.; (4) United States Department of Agriculture Agricultural Research Service, Canada

Maize (Zea mays L.) is susceptible to Aspergillus flavus infection, and subsequent contamination with aflatoxin, which is the most potent, naturally produced carcinogen. Currently, biocontrol using atoxigenic strains yielded limited success. In the present study, host-induced gene silencing (HIGS) was employed as a potential strategy to mitigate aflatoxin contamination in maize. The A. flavus omtA (aflP) gene, which encodes O-methyltrasferase, a key enzyme involved in the aflatoxin biosynthetic pathway, was selected as a possible target for suppression through HIGS. Using Agrobacterium transformation, an RNAi vector containing a portion of the omtA gene was introduced into immature B104 maize zygotic embryos. Twenty-eight transgenic plants were produced from twelve independent transformation events. Nineteen plants from six of the twelve transformation events, were confirmed by PCR to have the omtA gene. qRT-PCR analysis of RNA isolated from the transgenic leaf tissues showed a high level of variation in fungal target gene expression among the transgenic leaf tissues. Mature kernels from five of the events were also analyzed for changes in aflatoxin resistance using the kernel screening assay. The transgenic kernels from two of the events showed less aflatoxin (p=0.03 and p=0.06) than those kernels without omtA. The results from these preliminary studies suggest that silencing omtA gene can be used to reduce aflatoxin contamination in maize through HIGS.

Abstract Number: P10-337
Session Type: Poster