Evaluation of NASH and RT-PCR for the detection of PVY in dormant tubers and its comparison with visual symptoms and ELISA in plants

Detection of the common strain of PW (PVY degrees) in field-grown dormant p otato tubers, by nucleic acid spot hybridization (NASH) and reverse-transcr iption polymerase chain reaction (RT-PCR) was compared with diagnosis by vi sual symptoms and enzyme linked immunosorbent assay (ELISA) on leaves of ei ght potato cultivars, differing in their symptom expression and virus conte nt. NASH and RT-PCR readily detected PVY degrees in dormant tubers. The per cent agreement between NASH and RT-PCR ranged from 77.6 to 100 for cvs. inc luded in this study (AC Novachip, Atlantic, Norchip, Red Pontiac, Russet Bu rbank, Russet Norkotah, Shepody and Superior). ELISA on leaves was almost a s good as NASH and RT-PCR on dormant tubers, but required dormancy break. O nly two cultivars, namely Red Pontiac and Russet Burbank, could accurately be assessed, based on the visual symptoms. A very high degree of discrepanc y was observed for PVY degrees diagnosis between visual symptoms and other detection procedures for varieties like Russet Norkotah and Shepody, which are known to be latent carriers of PVY degrees. The use of NASH and RT-PCR in large-scale post-harvest testing is feasible.