Potato plant positive for PVYn has extended necroses on stem as well as on leaves. Is it typical for this virus or it can be a new strain of PVY?
Hi,
I would say it depends on the strain. Different PVY strains have differences in symptoms on solanaceae. Generally the PVY (N) is considered as "mild" (check the article) but I would say this depends on the interaction between virus and plant and their specificity. Stem necrosis is also plausible since is the main way to pass from leaves to tubers. Necrotic symptoms on stems can be found on the Crosslin et al. (2002) paper. Please have a look at the following material. An hypothesis might be that the virus is not expressed on leaves but still present, so the plant has resistance (or better saying tolerance) on leaves but not on stems, where symptoms are visible.
Article First Report of the Necrotic Strain of Potato virus Y (PVY N...
Article Blocking the systemic spread of potato virus y in the tissue...
Article Differential pathogenicity of two different recombinant PVYN...
https://www.creative-diagnostics.com/PVY-EIA-Kit-256241-468.htm
https://www6.inra.fr/pvy_organization_eng/content/download/3215/34356/version/1/file/tribodet+et+al.pdf
Article Strain-Specific Resistance to Potato virus Y (PVY) in Potato...
Best regards
Francesco Desiderio Thank you a lot. I think that environment is very important as well. We had extensive necrotic type of PVY symptoms at 2017 and 2019, but only mosaics at 2018, despite the same plant material (different generations with the same infection).
Alex Ignatov if you believe that the temperature range would have an impact, I would strongly reccomend you to test PVY in colder condition. As indicated from some papers, PVY resistance could be broken at higher temperature. When handling virus is always important to work in a controlled environment and never work above 28 or 30 °C, to avoid environmental stress on plants. Please check those papers, related to the temperature range.
Article Effect of temperature on resistance to Potato virus Y in pot...
Article Presence of necrotic strains of Potato virus Y in Mexican potatoes
Best regards
Dear Alex,
I'd like to add something more to valuable contributions of Dr. Desiderio.
As known, potato crops and their tubers are one of the most sensitive host to biotic and abiotic conditions. They even show symptoms to the merest unfavourable conditions. These symptoms vary to cultivars much more when compare other crops. So, PVYN symptoms vary with cultivar, plant age, environmental conditions and other PVY (PVYO) strain. Combination of PVYN and PVYO has generated PVYNTN, which can cause very severe and economically damaging symptoms of necrotic ringspots on tubers. Depending on virus strain and potato variety, symptoms vary from mild mosaic to severe foliar necrosis to plant death. Primary symptoms from the initial infection may differ from a secondary infection of the progeny plants. PVYN can appear symptomless or as a mild mosaic. Primary infection of PVYNTN shows mild mosaic, chlorotic foliage, crinkled leaves and necrotic rings on the tuber surface. Necrosis increases during storage and rings may become sunken, facilitating rotting. Secondary symptoms of PVYNTN show a distinct mosaic on leaves and severe necrosis on stems and veins leading to leaf drop.
Have you checked if it a mix infection?
Groundnut bud necrosis virus (GBNV) causes similar symptoms.
Mustafa A Adhab Thank you, we will test the plants for Tospovirus group. GBNV has never been reported in Russia before, and symptoms are similar, but not typical for GBNV.
Birol Akbaş Thank you for your comment. We are familiar with range of symptoms for PVYO , but PVVN is rather new strain here. Our methods do not differentiate additional variants of PVY. That is why I wonder if it can be something different from PVVN
Dear Alex, perhaps I could not express well. I mention PVYN +PVYO (=PVYNTN) combination can cause stem necrosis on some potato cultivars.
Francesco Desiderio Thank you for discussion. Average temperatures above 28-30oC are rare in our region, we have much more problems with insufficient for PVY range below 16oC, and virus cannot develop systemic infection at all. But, it seems that other factors are extremely important for symptoms variation. At 2016 (cold year) PVYo caused magnesium deficiency - like symptoms instead of ordinary mosaics.
Alex Ignatov thanks for the comments. I indeed think that virus-plant interaction is very specific and poorly explored. Environmental condition may have an important role in it and slightly changes in temperature, RH or light may influence the capability of the plant to "tolerate" the virus. Controlled environment is crucial to know if any of those factors may influence your test-plot results. Very interesting results about the magnesium deficiency-like symptoms! Here is some material about environmental-related researches on plant viruses (PVY included).
Article Environmental factors influencing aphid transmission of pota...
Article The Effects of High Temperature on Infection by Potato virus...
Article A Model to Explain Temperature Dependent Systemic Infection ...
https://www.cell.com/current-biology/pdf/S0960-9822(18)30412-3.pdf
https://www.apsnet.org/edcenter/disandpath/viral/introduction/Pages/PlantViruses.aspx
Best regards
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