Variability of Potato Virus Y in Potato Crops in France

Abstract

A collection of 332 PVY isolates, originating from potato crops, was characterized in order to seek the newly described PVY variants, PVY N W and PVY Z. Serologically, 284 samples were found to contain only PVY O , 36 samples to contain only PVY N , whereas 12 samples were doubly infected by both PVY O and PVY N. All 36 isolates, serologically PVY N ‐typed and 16 isolates serologically PVY O ‐typed, induced vein necrosis on tobacco. The latter 16 isolates reacted like a Polish standard PVY N W isolate and are probably new members of that PVY subgroup; in the panel of samples, they originated from potato cultivars never previously reported as infected by PVY N W and their high incidence probably indicates that they are more widespread than commonly accepted. Indexing of 108 PVY O isolates on three potato cultivars (Desiree, Eersteling and Maris Bard) carrying hypersensitivity resistance genes to PVY O , PVY C and PVY Z , respectively, revealed the presence of various pathotypes. Two isolates reacted as two standard isolates, designated PVY ZE , originating from Spain and previously suspected to be PVY Z members; these isolates were able to overcome the hypersensitivity genes in the three potato cultivars and consequently were members of a newly recognized pathotype. Another isolate evoked the reactions expected after infection with PVY Z. Surprisingly, PVY C was only found in one sample that was doubly infected by PVY O.