First Report of Capsicum chlorosis virus Causing Yellow Stripes on Calla Lilies in Taiwan.

Tomato spotted wilt virus (TSWV) and Calla lily chlorotic spot virus (CCSV) are two recognized species of the Tospovirus genus in the family Bunyaviridae infecting calla lily (Zantedeschia spp.). During 2005, 15 virus isolates were collected from different calla lily plants exhibiting yellow stripes on their leaves in Ho-Li, a major calla lily-production township in Taiwan. After three successive local lesion passages on Chenopodium quinoa Willd., diseased leaf tissues individually infected by these isolates were preserved in liquid nitrogen and used for subsequent identification studies. Using the tospovirus genus-specific primers gL3637 and gL4435c designed from the L RNA, an 800-bp DNA fragment was amplified in reverse transcription-PCR from all 15 isolates. Moreover, leaf extracts of the diseased calla lilies and the C. quinoa plants inoculated with the 15 virus isolates reacted with antisera against the nucleocapsid proteins (NP) of Capsicum chlorosis virus (CaCV)-gloxinia and Watermelon silver mottle virus (WSMoV), but not to monoclonal antibodies against the NP of TSWV, CCSV, Peanut chlorotic fan-spot virus (PCFV), or Impatiens necrotic spot virus (INSV) in indirect ELISA. These results indicate that the 15 virus isolates are tospoviruses belonging to the WSMoV serogroup. Additionally, we amplified and sequenced the full-length N gene from these tospovirus isolates using primers WN2328 (5'-CCATTGGTTTGCCTCCG-3') and WN3534 (5'-CGTCGACAGAGCAATCGAGGC-3') designed from the S RNA of WSMoV. The deduced amino acid sequences of the N protein from these 15 tospovirus isolates showed a greater than 92% identity to that of CaCV (GenBank Accession No. NC-008301). Furthermore, results of phylogenetic analysis of the 15 isolates on the basis of amino acids sequences, both genetic distance and parsimony trees indicated that they were all genetically clustered within CaCV using INSV, TSWV, and WSMoV as outgroups. The results indicate that the virus causing yellow stripes in calla lilies is a strain of CaCV. To our knowledge, this is the first evidence that CaCV can naturally infect calla lilies and cause yellow stripe symptoms. Reference: (1) F.-H. Chu et al. Phytopathology 91:361, 2001.