What is viroids?
What Does viroids Mean
It called viroid to an infective agent that can cause disease in their host. Although they function in a similar way to viruses , unlike viruses , viroids lack lipids and proteins.
Discovered in 1978 , viroids are known to infect plants . On the other hand, viroids that affect animals (including humans ) were not discovered .
Since they lack metabolic activity outside the cells they infect, neither viroids nor viruses are living beings. It is important to mention that, thanks to the autocatalysis of genetic material, viroids manage to infect their hosts.
Viroids are composed of a short ribonucleic acid ( RNA ) chain , which can be rod-shaped or circular. Experts, who have already discovered about three hundred viroids, consider them to be the least complex infectious organisms in terms of their structure and genes .
There are many issues about viroids that are still unknown. It is not known, for example, how they manage to replicate, although it is noted that they usually reside in the nuclei of cells. Nor have viroids been found to code for proteins or their RNA to act as messenger RNA .
Able to infect herbaceous or woody plants of the dicotyledonous and monocotyledonous families, viroids affect higher plants. High temperatures and light contribute to its replication and to the manifestation of the symptoms of the infection , which can affect tomatoes, potatoes and citrus fruits, to name a few possibilities.
It is important to emphasize that there are many possible hosts for viroids; Similarly, there are various diseases associated with viroids, some of which are mentioned below:
* Cadang-cadang of the coconut tree : it is a disease found especially in the coconut tree. Globally, it tends to appear mainly in the central Philippines. This disorder was discovered in 1927 and since then it has caused the death of several million palm trees on the island, since it is estimated that the annual number of victims is around one million. With regard to its impact on trade, this viroid directly hurts coconut oil manufacturers. Since the symptoms appear slowly, over up to fifteen years , it is not easy to diagnose this disease in time;
* Exocortis of citrus fruits : broadly speaking, we can say that this disease is noticed when vertical cracks and scales appear on the rind of the fruit, in addition to dwarfism and yellow spots. To avoid exocortis it is necessary to carry out adequate control of the crops, something that farmers assure is not difficult to achieve . Among the species most affected by this disease are some varieties of grapefruit, lemon and lime. The aforementioned symptoms can be seen below the point where the graft holder and graft meet;
* Spindle tuber of the potato : although the symptoms vary according to the type of potato, the environmental conditions, the years that the infection has lasted and the strain of the viroid, it is possible to name certain general signs, such as a stunted appearance , a marked dwarfism, withered, darkened, rough and slightly rolled leaves. This disease is especially serious given the importance of the potato in the industry.
In the context of viroids, we often come across the concept of a prion , an infectious agent that is made up of a protein with the ability to generate aberrant molecular aggregates. Among the degenerative diseases that it can cause are Creutzfeldt-Jakob , bovine spongiform encephalopathy and scrapie .