Article

Clay nanosheets for topical delivery of RNAi for sustained protection against plant viruses

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Abstract

Topical application of pathogen-specific double-stranded RNA (dsRNA) for virus resistance in plants represents an attractive alternative to transgenic RNA interference (RNAi). However, the instability of naked dsRNA sprayed on plants has been a major challenge towards its practical application. We demonstrate that dsRNA can be loaded on designer, non-toxic, degradable, layered double hydroxide (LDH) clay nanosheets. Once loaded on LDH, the dsRNA does not wash off, shows sustained release and can be detected on sprayed leaves even 30 days after application. We provide evidence for the degradation of LDH, dsRNA uptake in plant cells and silencing of homologous RNA on topical application. Significantly, a single spray of dsRNA loaded on LDH (BioClay) afforded virus protection for at least 20 days when challenged on sprayed and newly emerged unsprayed leaves. This innovation translates nanotechnology developed for delivery of RNAi for human therapeutics to use in crop protection as an environmentally sustainable and easy to adopt topical spray.

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Author information

Affiliations

  1. Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia

    • Neena Mitter
    • , Elizabeth A. Worrall
    • , Karl E. Robinson
    • , Ritesh G. Jain
    • , Christelle Taochy
    •  & Stephen J. Fletcher
  2. Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia

    • Peng Li
    • , G. Q. (Max) Lu
    •  & Zhi Ping Xu
  3. School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia

    • Christelle Taochy
    • , Stephen J. Fletcher
    •  & Bernard J. Carroll
  4. University of Surrey, Guildford GU2 7XH, UK

    • G. Q. (Max) Lu

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Contributions

N.M., Z.P.X. and G.Q.L. conceived the BioClay technology. N.M., E.A.W., K.E.R., B.J.C. and Z.P.X. wrote the manuscript. N.M., Z.P.X. and B.J.C. provided expertise and supervised the work. E.A.W. preformed the experiments on constructs and expression of dsRNA, dsRNA loading into LDH, breakdown of LDH and release of dsRNA, stability of dsRNA bound to LDH, dsRNA uptake studies and crop protection assays. K.E.R. preformed experiments on constructs and expression of dsRNA, dsRNA loading into LDH, stability of dsRNA bound to LDH and crop protection assays. P.L. preformed experiments on LDH synthesis and characterization. R.G.J. preformed experiments on the northern blot detection of dsRNA uptake. C.T. preformed experiments on the GUS reporter system. S.J.F. preformed all statistical and bioinformatics analyses. All authors edited the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Neena Mitter or Zhi Ping Xu.

Supplementary information

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    Supplementary Information

    Supplementary Figures 1–11, Supplementary Tables 1 and 2.