Dose-dependent RNAi-mediated geminivirus resistance in the tropical root crop cassava
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Cassava mosaic disease is a major constraint for cassava production in Africa, resulting in significant economic losses. We have engineered transgenic cassava with resistance to African cassava mosaic virus (ACMV), by expressing ACMV AC1-homologous hairpin double-strand RNAs. Transgenic cassava lines with high levels of AC1-homologous small RNAs have ACMV immunity with increasing viral load and different inoculation methods. We report a correlation between the expression of the AC1-homologous small RNAs and the ACMV resistance of the transgenic cassava lines. Characterization of the small RNAs revealed that only some of the hairpin-derived small RNAs fall into currently known small interfering RNA classes in plants. The method is scalable to stacking by targeting multiple virus isolates with additional hairpins.
KeywordsVirus resistance Cassava RNA interference Hairpin RNA processing
We thank Dr. John Stanley (John Innes Centre) for the ACMV clones, and Drs. Johannes Fütterer (ETH Zurich), Daniel Schöner (ETH Zurich) and Thomas Hohn (University of Basel) for helpful discussions. This work was supported by grants from the Eiselen-Foundation-Ulm and the Bill & Melinda Gates Foundation Grand Challenges in Global Health Initiative.
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