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Cadang-cadang is a disease caused by Coconut cadang-cadang viroid (CCCVd), a lethal viroid of Coconut (''Cocos nucifera''), Anahaw (''Livistona rotundifolia'') Buri (''Corypha utan''), and African Oil Palm (''Elaeis guineensis''). Cadang-cadang literally means 'dying dying' in Bicol. It was originally reported on San Miguel Island in the Philippines in 1927/1928. "By 1962, all but 100 of 250,000 palms on this island had died from the disease," indicating an epidemic.〔Haseloff, J.; Mohamed, N.A.; Symons, R.H. (1982) ''Viroid RNAs of cadang-cadang disease of coconuts''. Nature 299, 316-321.〕 Every year one million coconut palms are killed by CCCVd and over 30 million coconut palms have been killed since Cadang-cadang has been discovered. CCCVd directly affects the production of copra, a raw material for coconut oil and animal feed. Total losses of about 30 million palms and annual yield losses of about 22 000 t of copra have been attributed to Cadang-cadang disease in the Philippines.〔Zelazny, B. (1980). Ecology of Cadang-Cadang Disease of Coconut Palm in the Philippines. Phytopathology 70, 700-703.〕 == Characteristics == Viroids are small, single-stranded RNA molecules, ranging from 246 to 375 nucleotides long. Unlike viruses, they do not code for protein coats but contain genes for autonomous replication. With abilities to cause serious disease, they are more commonly found in a latent stage, and their mode of infection is mainly mechanical, though documented cases exist of vertical transmission through pollen and seed.〔Maramorosch, K. (1991). ''Viroids and Satellites: Molecular Parasites at the Frontier of Life''. Boston: CRC Press. ISBN 0-8493-6783-2.〕 The sequence and structure prediction of CCCVd has been documented. There are four low-molecular-weight RNA species (ccRNAs) found associated with cadang-cadang disease.〔Imperial, J.S.; Rodrieguez, J.B.; Randles, J.W. (1981). Variation in the Viroid-Like RNA Associated With Cadang-Cadang Disease: Evidence for an Increase in Molecular Weight With Disease Progress." Journal of General Virology 56, 77-85.〕 Of the four, two are related with the early stage of the disease: ccRNA 1 fast and ccRNA 2 fast. After several years, two other species appear and predominate: ccRNA 1 slow and ccRNA 2 slow. Moreover, they share sequence homology with other viroids.〔Haseloff,J.; Mohamed, N.A.; Symones, R.H. (1982). Viroid RNAs of cadang0cadnag disease of coconuts. Nature 299, 316-231.〕 Conditions for a viroid to infect its host include wounds on the host or infected pollen grain deposited into an ovule.〔 Not all of the mentioned conditions pertain to cadang-cadang. Tinangaja disease is caused by coconut trinangaja viroid (CTiVd), which has 64% sequence homology with CCCVd. This disease has been found in Guam. Coconuts from Asia and South Pacific have been found to have viroids with similar nucleic acid sequences of CCCVd. The pathogenicity of CTiVd is uncertain.〔Hanold, D. ''Detection of coconut cadang-cadang viroid-like sequences in oil and coconut palm and other monocotyledons in the South-west Pacific''. Annals of Applied Biology 118, 139-151.〕 C Coconut cadang-cadang viroid, also known as CCCVd, is responsible for a lethal disease of coconut plant first reported in the early 1930 in the Philippines. The name cadang-cadang comes from the word gadang-gadang that means dying in the local dialect.〔Hanold and Randles, Coconut Cadang-Cadang Disease and Its Viroid Agent, The American Phytopathological Society / Plant Disease / Vol. 75 No. 4, 1991.〕 CCCVd is the smallest known pathogen and it is biologically distinct from other viroids; it consists of circular or lineal single-stranded RNA with a basic size of 246 or 247, it is thought it can be transmitted by seed or pollen (with low transmission rates) and occur in almost all plant parts. Once infected, coconut palm shows yellow leaf spots and nut production ceases; from appearance of first symptoms to tree death, time ranges from around 8 to 16 years, but the pest is generally greater in older plants. It is estimated that over 30 million coconut palms have been killed by cadang-cadang since it was first recognised and the loss of production is valued at about $80 – $100 for each planting site occupied by an infected tree. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Cadang-cadang」の詳細全文を読む スポンサード リンク
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