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United States Department of Agriculture

Agricultural Research Service

Research Project: Characterization, Etiology, and Disease Management for Vegetable Crops

Location: Vegetable Research

Title: First report of potato spindle tuber viroid naturally infecting greenhouse tomatoes in North Carolina

Authors
item Ling, Kai-Shu
item Li, Rugang
item Panthee, Dilip -
item Gardner, Randy -

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 7, 2012
Publication Date: January 2, 2013
Citation: Ling, K., Li, R., Panthee, D.R., Gardner, R.G. 2013. First report of potato spindle tuber viroid naturally infecting greenhouse tomatoes in North Carolina. Plant Disease. 97:148.

Interpretive Summary: In Spring of 2012, an unusual severe disease (plant stunting, chlorosis and small fruits) was observed on a limited number of tomato plants in a research greenhouse facility in western North Carolina, with a disease incidence of over 18%. Based on the symptom characteristics and negative results for viruses, a viroid infection was suspected and then confirmed to be infected by Potato spindle tuber viroid (PSTVd) using polymerase chain reaction, sequencing and infectivity test. To our knowledge, this is the first report of a natural occurrence of PSTVd on tomato in the eastern U.S. The diseased plants were contained and properly disposed. The broader geographic distribution of PSTVd on tomatoes in the U.S. and the potential latent infection in potato and a number of ornamentals emphasize the need for greater enforcement on plant and seed health tests for viroids, not only on potato, but also on tomato seeds and selected ornamental propagating cuttings.

Technical Abstract: In Spring of 2012, an unusual severe disease (plant stunting, chlorosis and small fruits) was observed on 18% of tomato plants (Solanum lycopersicum L.) in a research greenhouse facility in western North Carolina. Over time, the disease spread to other tomato plants inside the greenhouse. Initial screenings for possible viruses using ELISA or RT-PCR were negative. However, Real-time RT-PCR showed a positive for pospiviroid on eight diseased plants and one seed samples. Expected full viroid genomic RT-PCR products (360 bp) were generated. A consensus genomic sequence was obtained from 22 full genomic clones, which shared the highest nucleotide sequence identity of 96.9% to several isolates of Potato spindle tuber viroid (PSTVd). Similar disease symptoms were observed on two “Rutgers” tomato plants two weeks post mechanical inoculation and the presence of PSTVd was confirmed by real-time RT-PCR. The diseased plants were contained and properly disposed. In the U.S., natural infection of PSTVd on tomato was first identified in California in 2010. To our knowledge, this is the first report of a natural occurrence of PSTVd on tomato in the eastern U.S. The broader geographic distribution of PSTVd on tomato and the potential latent infection in potato and a number of ornamentals emphasize the need for greater enforcement on plant and seed health tests for viroids, not only on potato, but also on tomato seeds and selected ornamental propagating cuttings.

Last Modified: 9/21/2014
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