Papaya Ringspot Virus (PRSV) Causing Ringspot Disease on Papaya in Bali

Abstract

In a survey of papaya plantation in Tabanan, Bali, some papaya cultivars were found showing papaya ringspot disease symptomps i.e. yelowing and mottle on leaves; and ring spot on fruits. The analysis of enzyme linked immunosorbent assay (ELISA) of symptom leaf with papaya ringspot virus (PRSV) antiserum shown the disease was corresponding to the PRSV. The test results showed that PRSV infected papaya in Bali and detected in Tabanan. Previously, there has been no reports of the existence of this disease in the area of ​​Bali. The objective of the study were to observe the variations of disease symptoms caused by PRSV, mapping the disease spread in Bali, and  determine the molecular character of  PRSV Bali isolate. Surveys were conducted to observe the variations of disease symptoms and mapping the disease spread. Molecular method was used to determine the coat protein (CP) sequence. Analysis of leaf samples from diseased plants by reverse transcription-polymerase chain reaction (RT-PCR) was conducted using a pair of primers specific to PRSV. Study result shown the disease was detected in Bangli village, Tabanan regency with the infection index 73,33% (11/15), whereas samples from other survey sites not found infected with PRSV.  On samples that infected with PRSV were found yelowing and stunting on leaves; and ring spot on fruits. Amplicons of 905 bp were successfully amplified. Result from BLAST and sequence alignments showed that Bali isolate had considerable homology to the China (Accession No. KF 033092.1) isolate (99.45% na-level). Results of phylogenetic analysis using Maximum Parsimony approaches with 1000 bootstrap replications indicates that Bali isolate is in a clade with the China  isolates (Accession No. KF 033092.1, KF 033089.1, KF 033078.1).

Keywords: papaya , symptom, infection index, disease spread, molecular character.