Background/context:

RNA silencing is an intrinsic defence response of plants against viruses. As a counter-defence, diverse virus-encoded proteins can suppress RNA silencing. We have demonstrated that RNA silencing-based transgenic immunity to Potato virusY breaks down following infection by a heterologous virus expressing the 2b silencing suppressor. To obtain durable resistance, it is imperative that we devise novel generic transgene design features, which will prevent suppression of RNA silencing. This will lead to “unbreakable” resistance to plant viruses with broad applicability across many viruses and crops following demonstration of proof-of-concept for utilising these novel strategies in planta in an industry relevant model system for plant-virus interactions.

 Aim:

This project aimed to design and evaluate in planta transgene constructs for stable RNA mediated virus resistance, targeting viral suppressors of gene silencing. The project also sought to gain a more detailed understanding of host-virus interactions leading to gene silencing and its suppression for the development of additional plant protection strategies.

Major Outcomes:

This project demonstrated the following outcomes: 
• Breakage of viral resistance due to a viral suppressor of RNA silencing was demonstrated in transgenic plants 
• “Unbreakable” resistance to CMV was achieved using intron-spliced hairpin constructs targeting the viral
    coat protein and 2b silencing suppressor 
• Pyramiding of sequences from two unrelated viruses in a hairpin construct provided immunity to both
   viruses 
• RNA silencing or its suppression did not affect global genome methylation in tobacco

For more information contact:

Dr Ralf Dietzgen
The University of Queensland
Phone: +61 (0)7 3346 62703
Email:  r.dietzgen@uq.edu.au