Tomato apical stunt viroid - Data Sheet

Authors: Hammond, Rosemarie

Submitted to: Center for Agriculture and Biosciences International (CABI) Invasive Species Compendium
Publication Type: Book / Chapter
Publication Acceptance Date: 6/20/2018
Publication Date: 6/22/2018
Citation: Hammond, R. 2018. Tomato apical stunt viroid - Data Sheet. Center for Agriculture and Biosciences International (CABI) Invasive Species Compendium. https://www.cabi.org/isc/datasheet/52804.

Interpretive Summary: Tomato apical stunt viroid (TASVd) is a small circular RNA molecule that infects crop and ornamental plants in the family Solanaceae in both production fields and in greenhouses. TASVd was first reported in tomato in Cote D’Ivore, Africa in 1980, but has since been reported in tomato and ornamentals in several countries worldwide. It is primarily a pathogen of tomatoes in which it is mechanically transmitted, is transmitted through seed, and is insect transmitted by bumblebees under greenhouse conditions. Infection in tomato leads to stunted plants and small and deformed fruit with up to 100% yield loss. TASVd does not produce symptoms in infected ornamental plants that may serve as a reservoir for infection through contact occurring during horticultural practices. Pathways for introduction include tomato seedlings, tomato seeds and ornamentals. Information is provided on potential risks and routes of infection to new areas, biology and ecology of the pathogen, seed borne aspects of the disease, economic impacts, diagnostic methods, and prevention and control measures. This information will be of value to growers of crops known to be susceptible and to quarantine and regulatory officials.

Technical Abstract: Tomato apical stunt viroid (TASVd), a member of the family Pospiviroidae, genus Pospiviroid, is a small, covalently closed, circular single-stranded, highly base-paired RNA molecule that ranges in size from 362 to 364 nucleotides. Viroids do not encode peptides or proteins, and use host proteins for replication, movement, and processing of replication intermediates, which distinguishes them from plant viruses. TASVd is primarily a pathogen of tomato (Solanum lycopersicum) and ornamental plants in the family Solanaceae in both production fields and in greenhouses. TASVd is easily mechanically transmitted, is transmitted through seed, and is insect transmitted under greenhouse conditions. Symptoms of TASVd infection in tomato include apical stunting, leaf epinasty, necrotic lesions, vein yellowing and small fruit. TASVd was first reported in tomato in Africa, but has since been reported in tomato and ornamentals in several countries worldwide. The incidence is sporadic and, in many cases, the viroid has been eradicated by destruction of infected material. It may have been spread through infected seed and by importation of asymptomatic ornamentals. Seedling and seed health testing using molecular methods is an important tool to prevent the introduction of TASVd. Information is provided on potential risks and routes of infection to new areas, biology and ecology of the pathogen, seed borne aspects of the disease, economic impacts, diagnostic methods, and prevention and control measures.