RNA turned into antiviral spray for plants

Nadezhda Bessonova, N+1

Australian scientists have developed a spray for plants that provides long-term suppression of viral genes based on the phenomenon of RNA interference. In the experiment, scientists protected tobacco plants from viruses for twenty days after a single spray. Such a spray can also be used to change the properties of plants, but scientists have so far concentrated on protecting crops from viruses and diseases. The description of the work is published in the journal Nature Plants (Mitter et al., Clay nanosheets for topical delivery of RNAi for sustained protection against plant viruses).

The suppression of viral genes is based on a natural plant protection system called RNA interference. When a cell is attacked by a virus, the cell "cuts" the double-stranded viral RNA into short RNA fragments, and uses them to recognize and completely destroy RNA chains of similar structure. In the absence of RNA, viral proteins are not formed, and thus the virus cannot reproduce.

RNA interference has been used for more than 10 years to suppress the activity of the desired genes both in the laboratory and in limited field studies. For example, the work of American scientists in 2015 demonstrated an RNA spray that kills insect pests. The disadvantage of this spray is its short–term effect - it is active for only a few days, since unprotected RNAs are rapidly destroyed. Farmers cannot afford to use this expensive spray with a frequency sufficient for the desired effect.

In the new work, the researchers combined RNA with clay nanoparticles: this composition, when sprayed, reliably adheres to the leaves of plants and withstands several watering. Positively charged clay particles bind and protect negatively charged RNAs from destruction. Over time, microscopic clay particles gradually break down, slowly releasing RNA. This approach made it possible to extend the protection of tobacco plants from viruses up to 20 days. Moreover, even new leaves that grew after spraying were protected – in plants and, for example, roundworms, the reaction to foreign RNA is systematic, spreading throughout the body.

The fight against viruses in agriculture is a big problem: farmers use toxic pesticides or switch to virus-resistant varieties created using genetic modification. Scientists note that at a reasonable cost, the new antiviral protection with silencer sprays can become an attractive alternative to pesticides and genetic modification of crops, which often takes a long time: the spray is non-toxic, and the RNA in the spray does not penetrate the skin and is quickly destroyed even when ingested. 

Portal "Eternal youth" http://vechnayamolodost.ru  12.01.2017