A Chlorotic Spot Disease on Calla Lilies (Zantedeschia spp.) Is Caused by a Tospovirus Serologically but Distantly Related to Watermelon silver mottle virus

Abstract

A new tospovirus, Calla lily chlorotic spot virus (CCSV), was isolated from calla lilies (Zantedeschia spp.) in Taiwan. Chlorotic spots, ranging from light green to yellow, appear on the middle leaves of the affected plants. Virions measuring 75 to 105 nm, similar in size to tospovirus particles, were present in crude extracts and ultrathin sections of diseased leaves. Of 35 plant species inoculated mechanically, 24, including wax gourd (Benincasa hispida) and zucchini squash (Cucurbita pepo), were susceptible to the virus. CCSV was transmitted from infected wax gourd by Thrips palmi to healthy wax gourd and zucchini squash. The virus was weakly related to Watermelon silver mottle virus (WSMoV) in enzyme-linked immunosorbent assay (ELISA) and western blot tests. WSMoV-specific N gene primers, however, failed to produce DNA fragments from total RNA extracts of CCSV-infected plants in reverse transcription-polymerase chain reaction (RT-PCR). Results of RT-PCR show that the conserved regions of the L genes of tospoviruses are present in CCSV.