Aarhus, Denmark
May 7, 2012
Scientists at Aarhus University have studied symptom development and influence on yield of five Potato virus Y types in five potato varieties. The results show that the five virus types produce different symptoms in the potato varieties and with different severity.
In Denmark, Potato virus Y – also known as PVY – is the most common of the potato viruses, and it causes large yield losses. PVY is not only a Danish phenomenon. It is present throughout the world, causing heavy losses in potatoes and other solanaceous species such as tobacco and chilli.
The virus can be classified into types with different biological characteristics. This means that each type has a biological characteristic that the other types do not have. The five types included in the study were PVYO, PVYN, PVYC, PVYNTN, and PVYW.
- The PVY-types develop different symptoms and of varying severity (weak or strong symptoms) in the different potato varieties. It is an interaction between the genetic composition of the individual PVY-type and the genetic background of the potato varieties, including their content of resistant genes, informs Steen Lykke Nielsen, Head of Research Unit at Aarhus University.
Field trial
The experiment included a comparison of five potato varieties infected with five types of PVY. The five potato varieties were Fakse, Folva, Kennebec, Royal and Saturna. In the experiment, the development of symptoms in the five varieties and the impact on yields were assessed. The influence of the virus types were compared with non-infected healthy control plants.
Development of symptoms was visually assessed during the growing season and compared with plants of the healthy control plot.
The influence of the PVY-types on yields was assessed on the basis of a comparison of the weight and number of tubers per plant from the virus-infected plants and the healthy plant.
The five PVY-types are not equally harmful
The results show – not surprisingly – that PVY has a significant influence on yield - both on the average weight of tubers and the average number of tubers harvested per plant. However, there are big differences in how aggressively the five PVY-types attack the potato plants.
- The results confirm that infection of PVY has a large influence on yield, both measured as weight gain and number of tubers. However, there are large differences in the adverse effects of the different PVY-lines, says Steen Lykke Nielsen.
The original type of Potato virus Y (PVYO) was shown to give the highest yield loss of the five types. PVYO gives a significantly lower yield in all the five varieties both in tuber weight and number of tubers per plant. At the other end of the scale, PVYN and PVYC appear hardly to influence on the yield in any of the five varieties.
Besides loss of profits, the study also shows that the five selected potato varieties all develop symptoms of PVY infection. However, there is a considerable difference between type and severity of the symptoms the individual varieties develop. This very much depends on the PVY-type they are infected with.
The study was funded by the Potato Levy Fund and was made in cooperation with the national potato advisor Lars Bødker from the Knowledge Centre for Agriculture.
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