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New strain of Plum Pox Virus found

A new strain of Plum Pox Virus (PPV), the most devastating viral disease of stone fruit, has been identified by researchers at INRA’s Fruit Biology and Pathology Unit in Bordeaux, Aquitaine in collaboration with Russian, Slovak and Spanish counterparts. Unlike almost all other known strains, the new strain can infect cherry trees. This finding was the subject of a study published in the international scientific journal Phytopathology.

Cherry tree orchard in blossom © INRA
Updated on 10/06/2014
Published on 09/10/2014

Plum Pox Virus (PPV), commonly known as sharka, affects apricot, peach, and plum trees, causing various symptoms and, in the worst cases, premature dropping of fruit. Depending on the variety of tree and its susceptibility to the virus, the viral strain and different agricultural parameters, losses can mount to 80% -100% of yield.

An international effort to identify the virus

The study began after cherry trees in Russia started showing symptoms of sharka. Russian researchers sent samples to their Slovak and French counterparts, who sequenced the genome and analysed the genetic sequences, respectively. Thanks to genetic comparisons, they were able to identify that a new strain of PPV was at the root of the problem. Lastly, Spanish researchers looked at serology-based techniques to detect the new strain. This broad collaboration allowed the scientists to in turn develop an effective technique of polymerase chain reaction (PCR) to detect the new PPV strain. PCR is a technology in molecular biology used to generate thousands of exact replicas of a given DNA fragment, which scientists can then use to run studies.

Mechanisms of infection still unknown

While cherry trees are often infected by several viruses at a time, they remain immune to the most common strains of sharka. That is, the virus cannot spread throughout the entire tree. That is why sharka is not currently a threat to cherry trees in Europe. This is not the case, however, with the new strain of PPV-CR (i.e. “Cherry Russia”), which can spread throughout the plant, and therefore poses a potential threat to European cherry trees. The mechanisms the new strain uses to infect cherry trees are still unknown, and more research is needed to boost knowledge of the strain’s capacity to infect.

The discovery of this new strain of CR leaves many questions unanswered. Scientists have not yet determined, for example, its epidemiological potential, and therefore do not know if it is capable of causing a serious epidemic. The damage the virus can inflict on European crops is therefore not easy to predict. Nevertheless, the identification of this new strain and the development of targeted detection techniques will help in forecasting, or even reducing, the risk of its spread to Europe.

reference

Glasa M, Prikhodko Y, Predaj a L, Nagyová A, Shneyder Y, Zhivaeva T, Subr Z, Cambra M, Candresse T. Characterization of sour cherry isolates of plum pox virus from the Volga Basin in Russia reveals a new cherry strain of the virus. Phytopathology,  2013 Sep;103(9):972-9. DOI: 10.1094/PHYTO-11-12-0285-R.