Detection of mixed virus infection with Papaya ringspot virus (PRSV) in Papaya (Carica papaya L.) Grown in Luzon, Philippines

Issue Date

4-2009

Abstract

The occurrence of mixed infection of other viruses with Papaya ringspot virus (PRSV) was determined by conducting a survey of papaya virus diseases in farmers' fields in 31 sites located in four papaya growing provinces in southern Luzon such as Laguna, Cavite Batangas and Quezon; and in three provinces in central Luzon such as Bulacan, Nueva Ecija and Tarlac. Virus infection was assessed based on symptoms, virus detection and virus transmission test. Out of 848 plants observed in the survey sites in southern Luzon, 70% had virus symptoms, while 30% did not show virus-like symptom. Generally, plants had symptoms of mosaic, leaf deformation, yellow-green leaf discoloration, oily streaks on petioles and ringspot on fruits. Among the 512 field-collected samples from all sites surveyed, 48 or about 9% reacted positively to Papaya mosaic virus (PapMV), 15 or 3% to Zucchini yellow mosaic virus (ZYMV), and 331 or 65% to PRSV in Enzyme-linked immunosorbent assay (ELISA). Among the 48 PapMV-positive samples, 24 were PRSV-positive, while 6 of 15 ZYMV-positive samples were also PRSV-positive. However, Reverse transcription-polymerase chain reaction (TR-PCR) analysis did not detect the presence of PapMV, ZYMV and Papaya leaf distortion mosaic virus (PLDMV) in field-collected samples. The transmissibility of PapMV and ZYMV tested in two serial passages of mechanical inoculation into healthy papaya seedlings, showed that at the first passage, 4% of inoculated papaya using virus source from field-colected samples reacted positively to PapMV in ELISA, while 7% to ZYMV. However, viruses were not detected in RT-PCR. Back-inoculated papaya in the second passage did not react positively to PapMV and ZYMV in both ELISA and RT-PCR. Although PampMV and ZYMV were detected in ELISA, the presence of the virus was not confirmed in RT-PCR and virus transmission test, together with PLDMV. Knowledge on the occurrence of mixed infection of other viruses with PRSV in non transgenic papaya would be useful in assessing the biosafety of PRSV-resistant transgenic ppaya conferred using PRSV genes; and in formulating effective disease management.

Source or Periodical Title

Philippine Journal of Crop Science

ISSN

0115-463x

Volume

34

Issue

1

Page

62-74

Document Type

Article

Frequency

tri-quarterly

Physical Description

tables/graphs

Language

English

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