ISHS Acta Horticulturae 1010: III International Humulus Symposium
HISTORY, ORIGIN, AND DIVERSITY OF HOP STUNT DISEASE AND HOP STUNT VIROID |
| Author: | T. Sano |
| Keywords: | Hop stunt viroid, hop stunt disease |
| DOI: | 10.17660/ActaHortic.2013.1010.9 |
| Abstract:
Hop stunt disease first emerged in Japan and reported as “dwarf hop” or “cedar-shaped hop” in the 1940s and the early 1950s. The disease emerged in Korea in 1988 and was confirmed in North America in 2004 and in China in 2007. The diseased plants develop yellowish green leaves and drooped leaf petioles in early to mid-growing season, and results in stunting of main and lateral bines. Depending on hop variety, visual stunting becomes apparent only several years after the infection. More serious is the reduction of the alpha-acid content, which is occasionally accompanied by reduction in the total cone numbers per vine. The alpha-acid content of sensitive cultivars is reduced to less than one half. Viroids are the smallest known pathogens and cause severe to mild diseases in economically important crops. They are single-stranded, circular, and self-replicating non-coding RNAs with a size of 250 to 400 nucleotides. Viroid replication is dependent on host transcriptional machinery, and pathogenicity depends entirely on interactions with cellular components of the host. Hop stunt disease (HSD) is caused by the Hop stunt viroid (HpSVd), a member of the Pospiviroidae family. Infection of hops by Apple fruit crinkle viroid also exhibits similar disease symptoms. HpSVd was first discovered from the dwarfed-hop, but soon after, it was found to have infected cultivated grapevines, citrus and stone fruits, including plum, peach, apricot, almond and Jujube. HpSVd is now considered to be a ubiquitous and genetically variable pathogen that has spread among cultivated crops worldwide. Unfortunately, all the HpSVd isolates have a potential to cause hop stunt, and current HSD epidemics in Japan, USA, and China may have originated from inter-specific transmission of HpSVd from cultivated grapevines to hops. | |
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