Table of Contents
What are the common symptoms of infections in PSTVd?
Symptoms. Mild strains generally cause no obvious symptoms in potatoes. However severe strains in sensitive cultivars may cause foliage to be spindly, very upright, with overlapping leaflets and sometimes with upward rolling of terminal leaflets. Plants will be stunted.
How does potato spindle tuber disease infect a host?
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.
What causes potato spindle disease?
Viroids. In 1971, studies of the potato spindle tuber disease showed that it was caused by a small, naked, single-stranded, circular molecule of infectious RNA, which was called a viroid (see later). Viroids have been found to be the cause of several dozen plant diseases.
Which infectious agent causes potato spindle tuber disease?
In 1960s, potato spindle tuber was thought to be a viral disease. In 1971, the agent of the disease was characterised as a low-molecular weight infectious ribonucleic acid (RNA), which was named as ‘viroid’, specifically Potato spindle tuber viroid (PSTVd)).
Which of the following viruses may cause a persistent viral infection?
Varicella-zoster virus, measles virus, HIV-1, and human cytomegalovirus are examples of viruses that cause typical persistent infections.
Are prions smaller than viruses?
Prions, so-called because they are proteinaceous, are infectious particles—smaller than viruses—that contain no nucleic acids (neither DNA nor RNA).
What is Chrysanthemum stunt disease?
Chrysanthemum stunt viroid (CSVd) is the causal agent of a major disease in cultivated chrysanthemum and is distributed worldwide, wherever chrysanthemums are grown commercially. CSVd is most closely related in sequence to tomato apical stunt viroid and citrus exocortis viroid.
Is Potato spindle tuber viroid a virus?
Potato spindle tuber viroid (PSTVd) can reduce the yields of potato by 65% and tomatoes 40 to 50%. PSTVd has been reported around the world, including in Australia. In Victoria, it was detected only in tomatoes and then eradicated. A viroid is like a virus but has a simpler structure.
Does virus cause potato spindle tuber disease?
Potato spindle tuber disease is not caused by prions, virus and bacteria.
What are the three types of persistent viral infection?
There are three types of overlapping persistent virus-host interaction that may be defined as latent, chronic and slow infection.
Who discovered viroids?
Dr. Theodor 0. Diener
The pathogen is called a viroid by its discoverer, Dr. Theodor 0. Diener, to distinguish it from a virus.
Do Viroids have a protein coat?
Viroids are the smallest infectious pathogens known, comprised solely of a short circular RNA without protein coats.
Who discovered Virusoids?
In 1971, Theodor Diener, a pathologist working at the Agriculture Research Service, discovered an acellular particle that he named a viroid, meaning “virus-like.” Viroids consist only of a short strand of circular RNA capable of self-replication.
What is crystallization of virus?
The process of transforming the components of a virus into organised particles and thereby describing their molecular structure using X-Ray crystallography technique is called crystallisation. This enables one to study the characteristics of a virus.
How soon after being exposed to Covid are you contagious?
Close contact with someone with COVID-19 Evidence shows that most COVID-19 transmission occurs closer to when symptoms start, generally in the 1–2 days before and the 2–3 days after symptoms begin. However, spread is still possible for up to 10 days after infection.
How is PSTVd transmitted to host plants?
Because PSTVd is mechanically transmissible, it can be introduced into potential host plants via the hands, clothes, or equipment used by people working in or visiting the greenhouse.
What is the global distribution of PSTVd in the world?
The viroid is regulated as a quarantine pest or regulated non-quarantine pest (RNQP) by many countries worldwide. Given that PSTVd can be present in asymptomatic hosts, the current geographical distribution is unclear.
Where does the PSTVd virus replicate?
Like most conventional RNA or DNA plant viruses, PSTVd moves long distances in the phloem. PSTVd replication occurs in the nuclei of infected cells and is catalyzed by RNA polymerase II, a host-encoded DNA-dependent polymerase normally involved in mRNA synthesis.
How do you detect PSTVd infections?
PSTVd infections may be detected by visual inspection in the field or greenhouse, dependent on the circumstances, i. e. viroid variant, host species and cultivar, and environmental conditions.