Pear blister canker 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: 11/15/2018
Publication Date: 11/30/2018
Citation: Hammond, R. 2018. Pear blister canker viroid - Data Sheet. Center for Agriculture and Biosciences International (CABI) Invasive Species Compendium. https://www.cabi.org/isc/datasheet/43926.

Interpretive Summary: Pear blister canker viroid (PBCVd) is a small circular RNA molecule that infects several cultivars of pear and is the cause of pear blister canker disease. PBCVd was first reported in pear in France in the 1960’s, and has since been reported in cultivated pear, wild pear and quince worldwide; however, the geographic distribution may be underestimated because of symptomless infections in certain hosts. It is primarily mechanically transmitted through pruning tools and grafting to infective propagative materials, which is a potential pathway for spread. PBCVd is regarded as a quarantine pathogen in the United States and several other countries. Information provided in the datasheet summarizes geographic distribution, potential risks and routes of infection to new areas, biology and ecology of the pathogen, economic impacts, diagnostic methods, and prevention and control measures. This information will be of value to growers of crops known to be susceptible to PBCVd and to quarantine and regulatory officials.

Technical Abstract: Pear blister canker disease, first reported in France in the 1960’s, is caused by pear blister canker viroid (PBCVd). PBCVd, a member of the family Pospiviroidae, genus Apscaviroid, is a small, covalently closed, circular single-stranded, highly base-paired RNA molecule that ranges in size from 312 to 316 nucleotides, does not encode peptides or proteins, and uses host proteins for replication, movement, and processing of replication intermediates. Disease can occur in several cultivars of pear (Pyrus communis), its major host, but most pear cultivars are tolerant and do not produce symptoms of infection; pear indicator hosts however are severely affected. PBCVd was initially reported in pear and quince, followed by wild pear and nashi and can experimentally infect species in other genera (Chaenomeles, Cydonia, Sorbus, Malus). Transmission through mechanical inoculation from pruning tools and grafting to infective propagative materials is a potential pathway for spread; no animal vector is known and it is not known to be seed transmitted. PBCVd has been reported in several European countries, Malta, Tunisia, Turkey, Australia, Japan, China, and the Americas; the geographic distribution may be underestimated because of symptomless infections in certain hosts. PBCVd is listed as a quarantine pathogen in several countries and the disease is managed by disinfection of contaminated equipment and use of viroid-free propagation material. Information in the datasheet includes geographic distribution, potential risks and routes of infection to new areas, biology and ecology of the pathogen, economic impacts, diagnostic methods, and prevention and control measures.