The green apple in the picture taken above seemed to have suffered from some kind of "skin allergy"!! It looks just like those itchy rashes on our own skin and the colour of those spots is somehow simliar. However, it is not "skin allergy"!! This is a kind of apple disease, Apple Scar Skin. It is one of the most destructive diseases affecting apple which is caused by Apple Scar Skin viroid (ASSVd). Fruit dappling appeared on several cultivars in Korea and has been distributed to major cultivated areas since 2001. ASSVd was identified from infected fruits by using nucleic acid sequence-based amplification with electrochemiluminescence (NASBA-ECL). Affected fruit bears small circular spots near the calyx end of the fruit. As the fruit matures, the spots enlarge and the spots increasingly contrast with the darkening background color of the fruit.
The mastermind of the apple disease mentioned earlier is VIRIOD!!
Well well well what are viriods?? Have any idea?
They are the smallest known agents of infectious disease. Whereas conventional viruses are made up of nucleic acid encapsulated in protein (capsid), viriods are uniquely characterized by the absence of a capsid. In spite of their small size, viroid ribonucleic acids (RNAs) can replicate and produce characteristic disease syndromes when introduced into cells.
Potatoes that suffered from PSTVd
Another example of plant disease caused by Viriods is Potato Spindle Tuber Viriod (PSTVd). Potato is the main host of this disease! Infected tubers are small, elongated, characteristically spindle or dumb-bell shaped, often with prominent bud scales evenly distributed over the surface. Futhermore, growth cracks may also occur.
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