First Report of Potato virus Y Strain N-Wilga Infecting Chrysanthemum in China.

Chrysanthemum (Chrysanthemum morifolium Ramat.) is a commercially important ornamental grown worldwide, and is also extensively used as an edible and medicinal plant. In the present work, viruses and viroids infecting chrysanthemum were investigated in China in 2012 and 2013. Typical viral symptoms were observed in field-grown chrysanthemum with leaf yellowing and mottled leaves in Wenjiang District, Sichuan Province, China. The incidence of these symptoms in the field was 12.3%. Chrysanthemum virus B (CVB), Tomato aspermy virus (TAV), Cucumber mosaic virus (CMV), Tobacoo mosaic virus (TMV), Chrysanthemum stunt viroid (CSVd), and Chrysanthemum chlorotic mottle viroid (CChMVd), which had previously been reported to infect chrysanthemum in China (2,3), were not detected by RT-PCR assay. Since these symptomatic chrysanthemum plants grew next to a tobacco field, viruses affecting tobacco were suspected as possible cause. Sixteen symptomatic leaves and 12 non-symptomatic leaves were collected and tested for Potato virus Y (PVY) presence using commercial PVY-specific DAS-ELISA kits (Catalog no. PSA20001, Agdia) Six samples were found positive for PVY. RT-PCR tests using specific primers for CP gene (CP-F 5'-ACTGTGATGAATGGGCTTATG-3'; CP-R 5'-GGCATATATGGTTCCTTTTTG-3') (4) amplified a single, expected 218-bp DNA fragment from chrysanthemum extracts from all six samples positive for PVY in ELISA. These six PCR fragments were sequenced and found 100% identical to each other. The sequence (GenBank Accession No. KJ174515) shared 99% identity with corresponding sequences of several PVY isolates (NC_001616, EF026076, HM590407, and JQ924288). The same six positive samples were subjected to a multiplex RT-PCR assay (1) to identify the PVY strain type, and all six PVY samples from Sichuan were found to belong to the PVY ^N-Wi strain. To our knowledge, this is the first report of the PVY ^N-Wi strain infecting chrysanthemum in Sichuan, China. References: (1) M. Chikh Ali et al. Plant Dis. 10:1370, 2013. (2) E. A. Nassar et al. Int. J. Virol. 8:14, 2012. (3) H. Yamamoto et al. J. Gen. Plant Pathol. 71:156, 2005. (4) J. Q. Zhang et al. J. Phytopathol. 161:92, 2013.