Occurrence of symptomless source of Piper yellow mottle virus in black pepper (Piper nigrum L.) varieties and a wild Piper species.

摘要

Symptomless nature of Piper yellow mottle virus (PYMoV) infection in three varieties of black pepper (Piper nigrum) (Panniyur 1, Panniyur 5 and Panchami) and a wild species of Piper (Piper colubrinum) was confirmed by polymerase chain reaction (PCR) using PYMoV specific primers. The virus could be transmitted from these PYMoV-infected symptomless plants onto symptom producing black pepper cv. Karimunda through mealybug vector, Ferrisia virgata and by graft transmission. About 20-50% seedlings showed typical symptoms of the PYMoV at 30 days after mealybug inoculations while it was 75-94% at 90 days after inoculation. PCR test of the inoculated seedlings confirmed the presence of PYMoV in 50-64%, 76-100% and 80-100% of plants in 30, 60 and 90 days after inoculation, respectively. Similarly, 50-66%, 91-100% and 100% of graft-transmitted plants showed typical symptoms of the disease at 30, 60 and 90 days after grafting. PCR test of the graft-transmitted plants showed 100% PYMoV infection at 60 days after grafting. The results clearly demonstrated the existence of PYMoV-infected symptomless plants that can act as source for secondary spread of the virus in the field.