Abstract
The fungus Fusarium verticillioides 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 F. verticillioides. Several of the resulting transformants exhibited reduced FUM1 gene expression and fumonisin production (24- to 3675-fold reduction in fumonisin FB1). Similar reductions in fumonisin production resulted from double-stranded RNA constructs with segments of FUM8, another fumonisin biosynthetic gene (3.5- to 2240-fold reduction in fumonisin FB1). FUM1 or FUM8 silencing constructs were transformed into three isolates of F. verticillioides. 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.
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Acknowledgements
We are grateful to Marcie Moore, Heather Walker and Mark Doehring for technical assistance. The mention of trade names or commercial products in this paper is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U. S. Department of Agriculture over other firms or similar products not mentioned. USDA is an equal opportunity provider and employer.
Funding
This study was supported by USDA CRIS Projects 5010-42000-047 (-049 and -050)-00D base funds.
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Johnson, E.T., Proctor, R.H., Dunlap, C.A. et al. Reducing production of fumonisin mycotoxins in Fusarium verticillioides by RNA interference. Mycotoxin Res 34, 29–37 (2018). https://doi.org/10.1007/s12550-017-0296-8
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DOI: https://doi.org/10.1007/s12550-017-0296-8