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Downregulation of transcription factor aflR in Aspergillus flavus confers reduction to aflatoxin accumulation in transgenic maize with alteration of host plant architecture

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We report success of host-induced gene silencing in downregulation of aflatoxin biosynthesis in Aspergillus flavus infecting maize transformed with a hairpin construct targeting transcription factor aflR.

Abstract

Infestation of crops by aflatoxin-producing fungi results in economic losses as well as negative human and animal health effects. Currently, the control strategies against aflatoxin accumulation are not effective to the small holder farming systems in Africa and this has led to widespread aflatoxin exposure especially in rural populations of sub-Saharan Africa that rely on maize as a staple food crop. A recent strategy called host-induced gene silencing holds great potential for developing aflatoxin-resistant plant germplasm for the African context where farmers are unable to make further investments other than access to the germplasm. We transformed maize with a hairpin construct targeting the aflatoxin biosynthesis transcription factor aflR. The developed transgenic maize were challenged with an aflatoxigenic Aspergillus flavus strain from Eastern Kenya, a region endemic to aflatoxin outbreaks. Our results indicated that aflR was downregulated in A. flavus colonizing transgenic maize. Further, maize kernels from transgenic plants accumulated significantly lower levels of aflatoxins (14-fold) than those from wild type plants. Interestingly, we observed that our silencing cassette caused stunting and reduced kernel placement in the transgenic maize. This could have been due to “off-target” silencing of unintended genes in transformed plants by aflR siRNAs. Overall, this work indicates that host-induced gene silencing has potential in developing aflatoxin-resistant germplasm.

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Acknowledgments

The authors wish to acknowledge financial support from the Bill and Melinda Gates Foundation through the Grand Challenge initiative (Grant No: OPP1058537) to Dr. Alakonya.

Conflict of interest

The authors declare no conflict of interest.

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Authors and Affiliations

  1. Institute for Biotechnology Research, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya

    Joel Okoyo Masanga, Sheila Cecily Ommeh & Amos Emitati Alakonya

  2. Plant Transformation Laboratory, Kenyatta University, P.O. Box 43844-00100, Nairobi, Kenya

    Joel Okoyo Masanga, Jonathan Mutie Matheka & Rasha Adam Omer

  3. Department of Microbiology, Kenyatta University, P.O. Box 43844-00100, Nairobi, Kenya

    Ethel Oranga Monda

Authors
  1. Joel Okoyo Masanga
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  2. Jonathan Mutie Matheka
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  3. Rasha Adam Omer
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  4. Sheila Cecily Ommeh
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  5. Ethel Oranga Monda
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  6. Amos Emitati Alakonya
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Corresponding author

Correspondence to Amos Emitati Alakonya.

Additional information

Communicated by E. Benvenuto.

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Masanga, J.O., Matheka, J.M., Omer, R.A. et al. Downregulation of transcription factor aflR in Aspergillus flavus confers reduction to aflatoxin accumulation in transgenic maize with alteration of host plant architecture. Plant Cell Rep 34, 1379–1387 (2015). https://doi.org/10.1007/s00299-015-1794-9

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  • DOI: https://doi.org/10.1007/s00299-015-1794-9

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