Pepino Mosaic Virus: A Globally Important Tomato Pathogen and a Rising Model in Molecular Virology

Pepino mosaic virus (PepMV); species: Potexvirus pepini; family: Alphaflexiviridae; order: Tymovirales.

PepMV virions are rod-shaped, non-enveloped, and flexuous particles. They encapsidate a monopartite, single-stranded, positive-sense RNA genome of approximately 6.4 kb, that encodes, in the sense orientation, a replicase, three triple gene block proteins, and the coat protein.

PepMV is widespread and causes a major disease in intensive tomato crops. Natural infections have also been reported in kachuma (also known as cachum or pepino dulce; Solanum muricatum), basil, wild tomato species, and weeds from various families growing near affected tomato crops. Experimentally, PepMV can infect plants of virtually all Solanaceae species.

Seven genetic types of PepMV are currently recognised: the original Peruvian (LP), European (EU), American US1, American US2, Chilean (CH2), the new Peruvian (PES), and Europe and the Asia-Pacific region (EAP).

PepMV is efficiently transmitted through mechanical means and shows a low rate of seed transmission. Insects, contaminated water, and agricultural tools have also been implicated in viral spread.

PepMV infections can range from asymptomatic to severe. Common symptoms in tomato plants include leaf blistering, chlorosis, mosaic patterns, and fruit bleaching, flaming, and marbling. Severe cases may exhibit necrosis in leaves, stems, and fruits. Symptom severity depends on the viral isolate, tomato cultivar, timing of infection, and environmental conditions.

No PepMV-resistant tomato varieties are currently available commercially. Therefore, preventive measures are commonly used strategies against PepMV. Cross-protection has proven highly effective and is widely employed for disease management.