Source: Global Potato News
A new species of the genus potyvirus infecting potatoes was discovered by scientists working at Science and Advice for Scottish Agriculture (SASA) in Edinburgh. In a recent scientific paper they are proposing the name “potato yellow blotch virus” (PYBV) to identify the virus in future. It was discovered in a potato breeding line.
Plants infected by the virus show isolated yellow blotches on the leaves. The unusual yellow symptoms on the foliage could have been mistaken for other potato-infecting viruses (such as potato aucuba mosaic virus, potato mop-top virus or yobacco rattle virus), according to the scientists.
They say the PYBV genome analysis of the new virus shows that it is closely related to potato virus A (PVA). With a couple of exceptions, symptomatology and host range analysis of PYBV was found to be comparable to PVA on solanaceous and non-solanaceous plant species. The susceptibility of potato cultivars to PYBV and PVA was similar. A range of assays (ELISA and PCR-based) have been developed to identify PYBV and survey seed and ware potato crops. In over five years of investigation, PYBV has not been found in commercial seed or ware potato crops in Scotland.
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Probably misidentified in the past
According to Christophe Lacomme, a senior virologist at SASA (a member of the research team with Carolyn Nisbet from the Potato Quarantine Unit), further studies are required to fully understand the epidemiology of PYBV, but, he says “we propose that since PYBV is very rare, and closely related to PVA with comparable cultivar resistance, it will be expected to have a low impact in potato crops, and be of a lesser threat to the trade than other potato-infecting viruses of the same family.”
Lacomme points out that PYBV might have been misidentified in the past as PVA by certification authorities worldwide, especially if ELISA tests were performed using polyclonal anti-PVA antibodies. “It is important to gather further information about PYBV and to know more about its epidemiology (for example, incidence in crops, natural hosts, transmission efficiency by insect vectors and so forth) in different areas and climate,” he says. “As like other virus species of the same family, PYBV is likely to be transmitted by aphid vectors and carried through to progeny tubers.”
More discoveries possible
With potatoes being grown in new areas, exposure to viruses infecting other plant species may increase in future. According to Lacomme, this–and the use of high-throughput (next-generation) sequencing–may lead to the discovery of more existing, but as yet unknown virus species infecting potato.
“Collaboration between scientists, certification authorities and the trade is essential to estimate the risk posed by pathogens, assess their impact, and develop strategies for early detection,” says Lacomme.
Authorities must remain vigilant
Gerry Saddler, chief plant health officer for Scotland, congratulated the team on their work and acknowledged that the authorities must maintain vigilance across the range of pests and pathogens that have the potential to affect such an important food crop. He went on to say “Thankfully, although novel, PYBV does not appear to be common nor a serious pathogen of potato, but it’s discovery serves to demonstrate the effectiveness of the Scottish certifying authority in maintaining vigilance for new and emerging threats.”