Pospiviroidae

Pospiviroidae is a family of viroids characterized by their small, circular, single-stranded RNA molecules that lack a protein coat. Despite their simple structure, they are potent plant pathogens that manipulate the host plant's genetic expression to favor their own replication, leading to severe physiological disruptions.

This family includes several economically damaging pathogens, most notably the Potato Spindle Tuber Viroid (PSTVd) and Chrysanthemum Stunt Viroid (CSVd). These pathogens exhibit a broad host range, infecting various solanaceous crops like tomatoes and peppers, as well as several ornamental species, causing widespread agricultural losses globally.

Symptoms of Pospiviroidae infection are systemic and typically involve stunted plant growth, leaf curling, epinasty, and chlorosis. In infected potato plants, the tubers show characteristic spindle-shaped malformations and cracking, while in other hosts, the infection may lead to poor fruit set and significantly reduced overall yield.

Transmission of these viroids is highly efficient through mechanical means, such as the use of contaminated pruning tools, contact between adjacent plants, and through seeds or pollen in certain species. Because they are highly stable, they can persist on equipment and surfaces for extended periods, making them difficult to eradicate once established in a greenhouse or field.

Integrated management is the only effective approach to mitigating the damage caused by Pospiviroidae. Recommended practices include:

• Strict adherence to certified, viroid-free seed and transplant protocols.
• Regular and thorough sterilization of all agricultural tools with appropriate disinfectants.
• Immediate rouging and destruction of symptomatic plants.
• Implementation of robust biosecurity measures and pest control to minimize mechanical transmission vectors.