RNA interference-based silencing of the alpha-amylase (amy1) gene in Aspergillus flavus decreases fungal growth and aflatoxin production in maize kernels

Authors: Gilbert, Matthew; Majumdar, Raj; Rajasekaran, Kanniah - Rajah; CHEN, ZHI-YUAN - Louisiana State University; Wei, Qijian - Mei Mei; Sickler, Christine; Lebar, Matthew; Cary, Jeffrey; FRAME, BRONWYN - Iowa State University; WANG, KAN - Iowa State University

Submitted to: Planta
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2018
Publication Date: 3/14/2018
Citation: Gilbert, M.K., Majumdar, R., Rajasekaran, K., Chen, Z.-Y., Wei, Q., Sickler, C.M., Lebar, M.D., Cary, J.W., Frame, B.R., Wang, K. 2018. RNA interference-based silencing of the alpha-amylase (amy1) gene in Aspergillus flavus decreases fungal growth and aflatoxin production in maize kernels. Planta. 247:1465–1473. https://doi.org/10.1007/s00425-018-2875-0.
DOI: https://doi.org/10.1007/s00425-018-2875-0

Interpretive Summary: Aspergillus flavus is a fungus that infects several several important food and feed crops, including corn, cotton and tree nuts. The fungus has the ability to produce toxic and carcinogenic compounds such as aflatoxins. Developing strategies and crops in an attempt to reduce A. flavus contamination and aflatoxin production is an area of intense research. One form of technology, called Host-induced gene silencing, shows great potential in reducing aflatoxin contamination in crops. In this strategy a host crop such as corn produces small biological molecules (called siRNA's) that can specifically target specific and crucial genes in the invading fungus and cause the target gene to be degraded. Here, we demonstrate that a corn line expressing these biological molecules effectively reduces gene expression in the fungus, thus resulting in decreased fungal growth and aflatoxin accumulation in the corn kernels. This work contributes to the development of a promising technology for reducing the negative economic and health impacts of A. flavus growth and aflatoxin contamination in food and feed crops. These findings will be useful to corn breeders and biotechnologists.

Technical Abstract: Aspergillus flavus is a saprophytic fungus and pathogen to several important food and feed crops, including maize. Once the fungus colonizes lipid-rich seed tissues, it has the potential to produce toxic secondary metabolites, the most dangerous of which is aflatoxin. The pre-harvest control of A. flavus contamination and aflatoxin production is an area of intense research, which includes breeding strategies, biological control, and the use of genetically-modified crops. Host-induced gene silencing, whereby the host crop produces siRNA molecules targeting crucial genes in the invading fungus and targeting the gene for degradation, has shown to be promising in its ability to inhibit fungal growth and decrease aflatoxin contamination. Here, we demonstrate that maize inbred B104 expressing an RNAi construct targeting the A. flavus alpha-amylase gene amy1 effectively reduces amy1 gene expression resulting in decreased fungal colonization and aflatoxin accumulation in kernels. This work contributes to the development of a promising technology for reducing the negative economic and health impacts of A. flavus growth and aflatoxin contamination in food and feed crops.