In vitro elimination of Piper yellow mottle virus from infected black pepper through somatic embryogenesis and meristem-tip culture

Piper yellow mottle virus (PYMoV) is known to infect black pepper (Piper nigrum) in India and other parts of the world. In the present study, somatic embryogenesis and meristem-tip culture alone and in combination with the antiviral agent ribavirin were attempted to eliminate PYMoV from infected black pepper explants. Cyclic somatic embryos obtained from the micropylar region of matured seeds collected from PYMoV-infected black pepper plants of six varieties were regenerated and hardened in the greenhouse. Testing of somatic embryo-derived plants by PCR showed virus elimination in 55-100% of the plants of the different varieties of black pepper. PYMoV elimination was increased when cyclic somatic embryos were pre-treated with ribavirin before regeneration. A protocol for meristem-tip culture of black pepper plants was developed that consisted of excising the meristem from PYMoV-infected black pepper plants and inoculating it in the regeneration medium containing antibiotics (to remove endophytic bacterial contamination), followed by rooting and hardening of the plants. Testing of the meristem-derived plants showed PYMoV elimination in 84% of the plants. Further elimination of the virus was achieved when meristem-tip culture was combined with ribavirin treatment.