Authors
Bihua Nie, Potato Research Centre, Agriculture and Agri-Food Canada (PRC-AAFC), Fredericton, New Brunswick E3B 4Z7, Canada, and National Center for Vegetable Improvement (Central China), MOE Key Laboratory of Horticultural Plant Biology, Hubei Provincial Research Center of Potato Engineering and Technology, Huazhong Agricultural University, Wuhan 430070, China;
Mathuresh Singh, Agricultural Certification Services, New Brunswick E3B 8B7, Canada;
Andrew Sullivan, Plant Propagation Centre, New Brunswick Department of Agriculture and Aquaculture, Fredericton, New Brunswick E3B 5H1, Canada;
Rudra P. Singh, retired, PRC-AAFC;
Conghua Xie, National Center for Vegetable Improvement (Central China), MOE Key Laboratory of Horticultural Plant Biology, Hubei Provincial Research Center of Potato Engineering and Technology, Huazhong Agricultural University; and
Xianzhou Nie, PRC-AAFC
Abstract
A field isolate of Potato virus Y (PVY) was collected in New Brunswick, Canada in 2007 due to unusual symptoms observed on different potato cultivars. To unveil the PVY strain identity, tobacco and potato bioassays, PVYO and PVYN-specific antibody-based enzyme-linked immunosorbent assays, and reverse-transcription polymerase chain reaction (PCR)-based genotyping were carried out. All the assays demonstrated that the isolate, designated as PVYO-FL in this study, belonged to the PVYO strain group. Greenhouse tests with the potato cvs. FL 1533 and Jemseg confirmed the severe nature of infection by PVYO-FL. The complete genome sequences of PVYO-FL and PVYO-RB, the latter a mild PVYO isolate, were determined. BLAST analysis revealed that the two isolates shared 97 and 98% sequence identities at the nucleotide and polyprotein levels, respectively. Further BLAST analysis unveiled that PVYO-FL shared 99.7% nucleotide sequence identity with PVYO-Oz, an isolate reported in New York, United States, whereas the PVYO-RB isolate shared 99.2% sequence identity with PVYO-139, a PVYO isolate reported in New Brunswick, Canada. A phylogenetic tree of available, full-length sequences of PVY isolates demonstrated two subgroups within the PVYO branch, one clustered with PVYO-RB and the other with PVYO-FL. Group-specific sense primers for differentiation of the two subgroups were developed and evaluated. A limited survey of potato tubers collected from a field plot at the Potato Research Centre, Agriculture and Agri-Food Canada, using the newly developed PCR primers, indicated that 65.3 and 2.4% of the PVYO-positive tubers were infected with PVYO isolates belonging to the PVYO-FL and PVYO-RB subgroups, respectively. Assessment of the pathogenicity of three representative isolates from each subgroup on the potato cv. Jemseg demonstrated that severe and mild symptoms were induced by the PVYO-FL-like and PVYO-RB-like isolates, respectively.
