''Peach latent mosaic

viroid Viroids are small single-stranded, circular RNAs that are infectious pathogens. Unlike viruses, they have no protein coating. All known viroids are inhabitants of angiosperms (flowering plants), and most cause diseases, whose respective economi ...

'' is a species of the genus ''

Pelamoviroid The ''Avsunviroidae'' are a family of viroids. There are four species in three genera (''Avsunviroid'', ''Elaviroid'' and '' Pelamoviroid''). They consist of RNA genomes between 246 and 375 nucleotides in length. They are single-stranded covalen ...

'', which belongs to the family ''

Avsunviroidae The ''Avsunviroidae'' are a family of viroids. There are four species in three genera (''Avsunviroid'', ''Elaviroid'' and ''Pelamoviroid''). They consist of RNA genomes between 246 and 375 nucleotides in length. They are single-stranded covalent ...

''. This family is characterized as having chloroplastic viroids with

hammerhead ribozyme The hammerhead ribozyme is an RNA motif that catalyzes reversible cleavage and ligation reactions at a specific site within an RNA molecule. It is one of several catalytic RNAs (ribozymes) known to occur in nature. It serves as a model system for ...

s. Peach latent mosaic viroid is a 336-351 nt

circular RNA Circular RNA (or circRNA) is a type of single-stranded RNA which, unlike linear RNA, forms a covalently closed continuous loop. In circular RNA, the 3' and 5' ends normally present in an RNA molecule have been joined together. This feature confer ...

which has a branched formation. This branched formation is stabilised by a

pseudoknot __NOTOC__ A pseudoknot is a nucleic acid secondary structure containing at least two stem-loop structures in which half of one stem is intercalated between the two halves of another stem. The pseudoknot was first recognized in the turnip yellow ...

between two kissing loops. Peach latent mosaic viroid was first described in the 1980s in Spain by a group of scientists. It is present in all

peach The peach (''Prunus persica'') is a deciduous tree first domesticated and cultivated in Zhejiang province of Eastern China. It bears edible juicy fruits with various characteristics, most called peaches and others (the glossy-skinned, non-fu ...

- and nectarine-producing areas of the world including Europe, Asia, North America and South America and the frequency of naturally occurring infection is high. Before the development of symptoms the disease is latent in peach trees for approximately 5–7 years. The symptoms of the disease include

necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dige ...

of buds, delayed shoot development, necrotic branches, premature ageing of trees, flower streaking, ripening deformations, enlarged rounded stones, circular discoloured areas on the fruit skin and in some cases mosaic, blotch, vein banding or calico appearance on infected leaves. Peach latent mosaic viroid is horizontally spread from plant to plant across a field by propagation of infected buds, pruning tools and green peach aphids. Vertical transmission of peach latent mosaic viroid through seeds can not occur.

References

External links

ICTV Online (10th) Report; ''Avsunviroidae''
{{Taxonbar, from=Q7157660 Viroids Viral plant pathogens and diseases Stone fruit tree diseases