An infectious agent associated with potato spindle tuber disease consists of free, low-molecular-weight RNA and has no p
The agent is a viroid. T. O. Diener discovered it while studying potato spindle tuber disease. Viroids consist of free RNA of low molecular weight and lack the protein coat found in viruses.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Viruses Viroids Prions and Lichens