Student - November 30, 2006

Multiple resistance in plants at a stroke

Imagine being able to make plants resistant to lots of viruses with just one genetic intervention. It is possible, Wageningen virologists discovered. In December they publish details of the technology involved, RNA silencing, in the Journal of General Virology.

RNA silencing is a hot topic at the moment, says Dr Marcel Prince of the Virology Group. ‘Researchers working on medical applications of RNA silencing won a Nobel prize this year. There is less interest in what’s happening in plant sciences, and that’s a shame, because what we describe in this article is new.’

The article is based on the PhD work of Dr Etienne Bucher, who received his doctorate in May 2006 in Wageningen. In the project Wageningen researchers perfected the method of using RNA silencing to make plants resistant to viral diseases.
‘RNA silencing happens in plants in the wild,’ says Prins. ‘We use the same mechanism in the cell, and make it more effective by introducing a new gene into the genome. It is a method that has relatively few other effects on the plant.’

RNA silencing is the name given to the mechanism whereby the plant cell destroys RNA strands of an attacking virus. The genetic material of most plant viruses consists of RNA. Viruses reproduce by forcing their way into cells, introducing their RNA stands and then making the cell reproduce this RNA. A key role in this mechanism is played by a larger protein complex that attaches itself to the RNA strands and destroys them. If you attach a copy of a type of RNA to a protein, then that protein will recognise the particular RNA type as a molecule that must be destroyed. ‘We have shown that it is possible to attach different sorts of RNA to the protein,’ adds Prins. ‘And that by using a new gene with a protein attached to it you can produce a plant genome that can destroy various viruses. In this way you can make a plant resistant to all known virus diseases in one go.’

An additional advantage of the Wageningen method is that it can be used for all plant crops, and that it is surprisingly easy to give a plant the desired characteristics. Prins thinks that is why there is so much interest in the method: ‘I’ve been doing science for a while now, but I’ve never had so many requests for reprints as for this publication.’

The seed companies that were involved in the research have already used the technology: crops with multiple resistance are available thanks to RNA silencing. The advantages are obvious says Prins. ‘Insecticide use can be reduced considerably with these multi-resistant crops. Many insects that land on plants are not dangerous themselves, it’s the viruses they transmit that destroy harvests.’ Nevertheless the companies involved are unlikely to do much with the new crops in Europe. ‘They are frightened of the consumer reaction,’ explains Prins. ‘They don’t want to get their fingers burned.’