Biological and molecular evidence of papaya ring spot virus pathotype P from mid-hills of Meghalaya, India

Abstract

Papaya ring spot virus (PRSV) is the limiting factor of papaya production in India irrespective of agro-climatic conditions and it may cause crop losses up to 85–90%. In this study, diagnostic survey on PRSV was conducted in mid-hills of Ri-Bhoi district, Meghalaya, India during April to June, 2015. Reverse transcription polymerase chain reaction assay detected PRSV infection in 38 of 53 samples collected from surveyed locations with an average incidence of 71.7%. The representative isolate (PRSV-P:Umiam) from mid-hill Meghalaya was maintained in healthy papaya seedlings by standard sap inoculation method and typical symptoms were expressed within 21–24 days post inoculation. Studies on the physical properties revealed that the dilution end point of PRSV-P:Umiam at 10−2, longevity in vitro for 18 h and thermal inactivation point in between 50 and 55 °C. Among the cucurbitaceous hosts, pumpkin (Cucurbita pepo) alone exhibited chlorotic lesions on leaves within 20–25 days post inoculation. The partial coat protein (CP 750 bp) of PRSV-P:Umiam gene shared maximum nucleotide (~ 95%) and amino acid (~ 98%) identity with PRSV isolates reported from northern and eastern India. The CP based phylogeny clustered PRSV-P:Umiam with the PRSV isolates from north and east India.