Potato spindle tuber viroid

Discovery

It was discovered in 1971 by Theodor Otto Diener, who was a plant pathologist at the U.S Department of Agriculture's Research Center in Beltsville, Maryland. He named it viroid because it is 1/80th the size of a virus.

Strains and their symptoms

Different strains of PSTVd exist and symptoms range from mild to severe. Mild strains produce no obvious symptoms. Symptoms in severe strains are dependent on environmental conditions and are most severe in hot conditions. Symptoms may be mild in initial infections but become progressively worse in the following generations. Common symptoms of severe infections include color changes in the foliage, smaller leaves and spindle-like elongation. Sprouting also occurs at a slower rate than in unaffected potatoes. Infected tomatoes are slower to show symptoms which include stunted growth with a ‘bunchy top’ caused by shortened inter-nodes. Leaves become yellow or purple and often become curled and twisted. Necrosis eventually occurs in the veins of the bottom and middle leaves and the top leaves decrease in size. Fruit ripening is also affected leading to hard, small, dark green tomatoes.

Long distance spread of PSTVd usually occurs via infected seeds but transmission via aphids (Myzus persicae) also occurs but only in the presence of PLRV (potato leaf roll virus). Mechanical transmission also occurs once it has been introduced to an area.

Primary and secondary structure of PSTVd

PSTVd comprises 359 nucleotides. Used is the type genome V01465.

Course of infection

Systemic movement within the infected host is through the phloem.p.114, " In the first experimental investigation on viroid systemic movement within an infected plant, Palukaitis (99) showed that PSTVd moved from a photoassimilate-source leaf into sink organs in a pattern consistent with phloem transport. This was supported by in situ localization of PSTVd in the phloem (144)."

References

Bibliography

• Agrios, George N., 1936- Plant pathology (3rd edition) San Diego: Academic Press, 1988.
• Singh, R.P; Fletcher J.D.; "Background of disease (potato spindle tuber) and method of control", Agriculture and Agri food Canada, Crop & Food Research New Zealand Retrieved November 15, 2007
• DEFRA Plant Health
• "Pathogen and plant damage (potato spindle tuber)" Retrieved November 15, 2007, from George N. Agrois, Plant Pathology (3rd Ed) San Diego: Academic Press,(1988).

References

1. Diener TO. (August 1971). "Potato spindle tuber "virus". IV. A replicating, low molecular weight RNA". Virology.
2. (2006-03-02). "ARS Research Timeline - Tracking the Elusive Viroid".
3. [http://www2.oakland.edu/biology/chaudhry/pics/Viroids%5B1%5D.pdf Discovery of Viroids] {{webarchive. link. (2016-03-03)
4. Zimmer, Carl. (September 25, 2014). "A Tiny Emissary From the Ancient Past". [[New York Times]].
5. (1982). "Nucleic Acids and Proteins in Plants II : Structure, Biochemistry and Physiology of Nucleic Acids". Springer Berlin Heidelberg.
6. (2017-06-28). "First finding of ''Potato spindle tuber viroid'' (PSTVd) in seeds of ''Solanum sisymbriifolium'', originating in Asia - June 2017".
7. Mink, G. I.. (1993). "Pollen and Seed-Transmitted Viruses and Viroids". [[Annual Reviews (publisher).
8. (October 2002). "Potato spindle tuber viroid Strains of Different Pathogenicity Induces and Suppresses Expression of Common and Unique Genes in Infected Tomato". Molecular Plant-Microbe Interactions.
9. (February 2008). "Double-stranded RNA interferes in a sequence-specific manner with the infection of representative members of the two viroid families". Virology.
10. (2021-10-04). "Disease profile: Potato Spindle Tuber Viroid".
11. (June 1997). "Evidence for heterologous encapsidation of potato spindle tuber viroid in particles of potato leafroll virus". J Gen Virol.
12. (May 2022). "Transmission of potato spindle tuber viroid between Phytophthora infestans and host plants". Vavilovskii Zhurnal Genet Selektsii.
13. (9 October 2010). "Mechanical transmission of ''Potato spindle tuber viroid'' between plants of ''Brugmansia suaveoles'', ''Solanum jasminoides'' and potatoes and tomatoes". Eur J Plant Pathol.