First report of potato tuber necrotic ringspot disease associated with PVY recombinant strains in Ireland

Keywords: Potato virus Y, enzyme-linked immunosorbent assay (ELISA), Irish potato crops

Potato tuber necrotic ringspot disease (PTNRD) as described by Kus et al., (1992) is found worldwide but has not previously been identified in Ireland. In recent years necrotic symptoms, veinal necrosis, spots, mottling, mosaics and chlorosis have been observed on potato foliage in different regions across Ireland. In 2011 and 2012 affected leaves were serologically tested by double antibody sandwich-enzyme-linked immunosorbent assay (DAS-ELISA) according to the method of Clarke et al., (1977). In some instances these symptoms were associated with PVY. Further analysis of PVY positive samples using RT-PCR, as described by Lorenzen et al., (2006) confirmed the presence of the recombinant strains PVY^NTN and PVY^N:O (Fig. 1). No tuber samples were available to determine if their presence was associated with PNTRD.

In 2013, foliage of the cultivar Nicola grown in County Carlow, Ireland showing mosaic, veinal necrosis and chlorosis (Fig. 2) was sampled and serologically and molecularly analysed as described above. Presence of PVY was confirmed by DAS-ELISA, and RT-PCR analysis confirmed the presence of both PVY^NTN and PVY^N:O. Tubers from the infected plants were harvested and, following storage at ambient temperature for 28 days, developed the typical superficial necrotic ringspot disease (Beczner et al., 1984) (Fig. 3). This is the first report of PTNRD associated with PVY recombinant strains in Ireland.