abstracts - INCDCSZ Brasov

DISSEMINATION OF POTATO VIRUS Y (PVY) ISOLATES UNDER FIELD
CONDITIONS
Schwärzel R., Gugerli P., Derron J., Reust W.
Swiss Federal Research Station for Plant Production, Agroscope Changins-Wädenswil ACW, case
postale 1012, CH-1260 Nyon
Hebeisen Thomas. Swiss Federal Research Station for Plant Production, Agroscope Reckenholz-
Tänikon ART, CH-8046 Zurich
Keywords: Potyvirus Y (PVY), PVY isolate, ELISA test, variety assessment
In the last few years, many new isolates of PVY (potyvirus Y) appeared in the potato fields in
Switzerland. New recombinations have been revealed by PCR methods (Rigotti and Gugerli, 2004).
The dissemination rate and the sensitivity of the cultivars changed fundamentally. Switzerland has
intensive trade exchange of potato seed with different European areas and countries. These exchanges
accelerate the dissemination of the different predominant PVY types. Early nineties, first PVY NTN
potato tuber ringspot disease symptoms on new breeding variety Lido have been observed in
Switzerland. In the beginning of this millenary, PVY Wilga has been detected.
The dissemination of six different PVY isolates on six different cultivars has been studied under field
conditions. The rectangular small potato plots, 800 seed tubers each, were separated by twelve meters
bands of oat. This cereal was sown at same time than potatoes but since oat grew before potatoes, it
could help reducing attractiveness for wing aphides and to move between plots at the beginning of the
growing season. In each variety plot, 4 % of a single PVY isolate infected potato plants were inserted.
For the control of the dissemination of PVY by wing aphids from one plot to another, PVY O and
PVY N antibody ELISA tests have been conducted separately.
Under these field conditions, PVY ring necrosis symptoms on tubers have been detected in promising
new varieties. Dissemination of different PVY isolates from one plot to another, isolated with oat
bands, was very low in 2005 and 2006. The cultivar Lady Christl was resistant to all PVY isolate
infections; Bintje and Charlotte were sensitive to PVY and very sensitive to PVY NTN and PVY Wilga
isolates. Charlotte was very sensitive to PVY N isolates in 2006. Spread of PVY O and PVY N was lower
then PVY NTN and PVY Wilga isolates. Ring necroses on tubers were mostly observed on Nicola and
rarely on Bintje, Desiree or Charlotte.
Some new PVY isolates were responsible for PVY ring necroses on tubers for sensitive varieties like
Nicola, Ditta, Erntestolz, Verdi, Juliette, Derby, Arielle and Amandine. The sensitivity of cultivars to
PVY is variable and differs according to the necroses tuber-sensitivity.
Introduction
Switzerland is a small mountain country with 7 million inhabitants and a large mountain area.
Arable land represents only one quarter of the total surface (40'000 km 2 ). Around 30 European potato
varieties are cultivated on these 12'000 ha with an average yield of 38 to 42t/ha. The seed production
covers about 1500 ha. Located in the centre of Europe, Switzerland is not a member of the European
Union.
In Switzerland the main potato production area is located on the Plateau, a long piece of land, 400 to
800 m above sea level between the Jura (a low-altitude mountain range) in the North and the Alps in
the South. Several kind of wing aphid populations, as virus vector, appears early in spring at the same
time as potato plant emergence. In Switzerland, the wing aphid development is very favourable, much
more then in northern part of Europe with constant cool, windy areas. For economical and rational
evolution reasons, the seed production in Switzerland has been transferred from isolated high altitude
above sea level areas to high-density potato growing areas on the Swiss plateau. The renewal rate of
seed potatoes is high with about 70%. Usually, 10 to 15 % of the seeds, mostly basic seed category,
are imported from Holland, Germany, or Bretagne (France), and exceptionally from North of France,
Belgium or Austria. Because of the regular potato import of variable origin and the fast dissemination
rate of the virus, Switzerland is characterized as a collector area of many types of potyvirus. Soft
viruses such as PVS, PVX, PVA and PVM, but also severs viruses such as PLRV and many types of
potyvirus Y isolates.
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