Tomato zonate spot virus (TZSV) (proposed)
Significance: In 2005, a devastating virus-like disease was observed on field-grown tomatoes and chili peppers in Yunnan Province, China. Diseased plants exhibited concentric zoned ringspots on ripe fruits and necrotic lesions on leaves. Based on particle morphology, host range, and serological properties, the causal agent of this disease was determined to be a new species of tospovirus, tentatively named Tomato zonate spot virus (TZSV). Symptoms of TZSV infection varied widely, depending on the cultivar, stage of plant growth at the time of infection, and environmental conditions. Plants infected in the early stages of growth were severely stunted and failed to produce fruit. If older plants were infected, young fruit were often malformed and showed slightly sunken patches or rings of small necrotic flecks, while on ripe fruit the concentric ringspots were more conspicuous. Internal necrotic lesions, which developed on the stem of infected plants, sometimes resulted in plant death. Mechanical inoculation of experimental test plants revealed that members of the Solanaceae plant family were more susceptible to TZSV infection than plants of other families. However, during field surveys, leaves of carnation (Dianthus caryophyllus), taro (Colocasia esculenta), curly dock (Rumex crispus) and spinach (Spinacia oleracea) were also found displaying TZSV-like symptoms, and when tested, reacted positively to TZSV-specific antiserum. These results suggest that TZSV has a wide host range that includes both agricultural crops and ornamental plant species. Three thrips species (Frankliniella occidentalis, Thrips palmi and T. tabaci), potential vectors of TZSV, were also found in the fields surveyed, however, confirmation of disease transmission by these thrips is still under investigation.
Issues of Concern: Vegetable crops like tomato and pepper are hosts to dozens of different viruses, many with diverse biological properties and highly variable impacts. Keeping track of these viruses, their hosts, distributions, and potential pathways, make Phytosanitary regulation of these types of organisms difficult. However, given that TZSV is at this time only known from one part of China, its exclusion from other vegetable production areas may be a worthwhile objective.
Jia-Hong Dong, Xiao-Fei Cheng, Yue-Yan Yin, Qi Fang, Ming Ding,Ting-Ting Li, Li-Zhen Zhang, Xiao-Xia Su, Jenifer Huang McBeath and Zhong-Kai Zhang. 2008. Characterization of Tomato zonate spot virus, a new tospovirus in China. Archives of Virology Vol. 153 (No.5): 855-864.