Location: Crop Bioprotection ResearchTitle: Reducing production of fumonisin mycotoxins in Fusarium verticillioides by RNA interference Author
Submitted to: Mycotoxin Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/2017
Publication Date: 11/26/2017
Citation: Johnson, E.T., Proctor, R., Dunlap, C.A., Busman, M. 2017. Reducing production of fumonisin mycotoxins in Fusarium verticillioides by RNA interference. Mycotoxin Research. 34:29-37. https://doi.org/10.1007/s12550-017-0296-8.
Interpretive Summary: Corn ear molds produce harmful toxins under certain weather conditions and insect damage. One toxin producer, Fusarium verticillioides, can grow inside the ear before making the toxins, and is therefore difficult to control in the field. Gene segments were identified that caused dramatically lower levels of production of toxins when overexpressed in this ear mold. These reductions were produced in three geographically distinct ear mold strains from the U.S., indicating the gene segments could have broad effectiveness. These gene segments can now be tested for effective reduction of mycotoxins when expressed by corn, potentially resulting in safer corn for producers and consumers.
Technical Abstract: The fungus Fusarium verticillioides (Fv) is a maize pathogen that can produce fumonisin mycotoxins in ears under certain environmental conditions. Because fumonisins pose health risks to humans and livestock, control strategies with minimal risk to the environment are needed to reduce fumonisin contamination. Host-induced gene silencing is a promising technique in which double-stranded RNA expressed in the plant host is absorbed by an invading fungus and down-regulates genes critical for pathogenicity or mycotoxin production in the fungus. A key preliminary step of this technique is identification of DNA segments within the targeted fungal gene that can effectively silence the gene. Here, we used segments of the fumonisin biosynthetic gene FUM1 to generate double-stranded RNA in Fv. Several of the resulting transformants exhibited reduced FUM1 gene expression and fumonisin production. Similar reductions in fumonisin production resulted from double-stranded RNA constructs with segments of FUM8, another fumonisin biosynthetic gene. FUM1 or FUM8 silencing constructs were transformed into three isolates of Fv. Whole genome sequence analysis of seven transformants revealed that reductions in fumonisin production were not due to mutation of the fumonisin biosynthetic gene cluster and revealed a complex pattern of plasmid integration. These results suggest the cloned FUM1 or FUM8 gene segments could be expressed in maize for host-induced gene silencing of fumonisin production.