A Fast-Reacting Bioassay for the Tobacco Veinal Necrosis Strain of Potato Virus Y (PVYN). M. SINGH, Postdoctoral Fellow; Agriculture and Agri-Food Canada, Research Branch, Research Station, P.O. Box 20280, Fredericton, New Brunswick E3B 4Z7, Canada. R. P. SINGH, Research Scientist, Agriculture and Agri-Food Canada, Research Branch, Research Station, P.O. Box 20280, Fredericton, New Brunswick E3B 4Z7, Canada. Plant Dis. 78:775-778. Accepted for publication 19 April 1994. Copyright 1994 Department of Agriculture, Government ol Canada. DOI: 10.1094/PD-78-0775.

Solarium brachycarpum Plant Introduction 498021 reacted with necrotic symptoms when inoculated with various isolates of the tobacco veinal necrosis strain of potato virus Y (PVYN). Symptoms consisted of necrotic local lesions, wilting of leaflets, collapse of petioles, and death of entire plants within 7-10 days after inoculation. Inoculating S. brachycarpum plants with isolates of the common strain, PVY°, produced mosaic symptoms within 13-16 days. Potato viruses M, S, and X did not cause any visible symptoms in S. brachycarpum plants, but potato virus A produced mosaic symptoms. Since the presence of potato virus X (PVX) in S. brachycarpum plants or simultaneous inoculation with PVX and PVY did not change the PVY symptomatology, there is no need to remove PVX from the sample, as is required for PVYN detection with the tobacco bioassay. Necrotic symptoms caused by PVYN isolates appeared at a temperature range of 20-35°C and at a light intensity of 48-72 to 140-196 μEs-1.m-2. Therefore, this plant is suitable for bioassay under a range of environmental conditions. S. brachycarpum developed symptoms typical of either PVYN or PVY0 isolates when inoculated with samples from potato foliage, sprouts, or tubers infected with those strains.

Keyword(s): Dot-immunobinding assay, indicator host for PVY, PVY strains