Outbreak of
Papaya ringspot virus in papaya orchards in St. Kitts
M. Chin1, L. Rhodes2 and P. Tennant1,3*
1 Biotechnology
Centre, University of the West Indies, Mona, Kingston 7, Jamaica
2 Caribbean
Agricultural Research and Development Institute (CARDI), Fortlands, Basseterre,
St. Kitts
3 Department
of Life Sciences, University of the West Indies, Mona, Kingston 7, Jamaica
*paula.tennant@uwimona.edu.jm
Accepted for publication 08/10/07
Fruit tree
production has become increasingly more important in the agricultural industry
of St. Kitts.
This is because of an
increasing demand for
local fruits resulting from an expanding local tourism sector. Papayas (Carica
papaya), along with bananas and mangoes, are commonly grown to provide the
sector with the ‘Kittian fruit plate’.
In
October 2002,
mosaic symptoms on leaves and ringspot blemishes on fruits were observed on
papaya trees in orchards at two locations along the northwest coast
of St. Kitts (Brimstone Hill and Fahies). Samples were
tested by
double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA, Agdia
Inc.) for Papaya ringspot virus (PRSV).
In addition, crude sap
extracts (1: 20) from affected leaf samples were mechanically inoculated onto
papaya seedlings. Symptoms
typical of PRSV (Purcifull et al., 1984), including
vein clearing followed by mosaic
development and leaf distortions, were observed in the inoculated plants within
2 weeks. All
original samples and the indicator plants tested positive in DAS-ELISA. Reverse
transcriptase polymerase chain reaction (RT-PCR) using primers to the capsid
protein gene (Slightom, 1991)
was performed. A single amplicon of the expected size
(~ 996 bp) was obtained with samples from both locations. RT-PCR
amplicons were subsequently cloned into the vector pEPT8 (Ling et al.,
1997) and sequenced. The two sequences were 99% identical and showed high
nucleotide identities (90 to 97%) with PRSV from Jamaica (DQ104812), Cuba
(DQ089482), Florida (AF196839), and Brazil (AF344650) and a lower identity of
89% identity with an isolate from Puerto Rico (AF196838). This is the first
confirmed report of PRSV in St. Kitts. Despite
eradiction measures and destruction of the infected crop, the pathogen has
subsequently spread throughout the island, wiping out approximately 90% of
production.
References
Ling KS, Zhu
HY, Alvizo H, Hu JS, Drong RF, Slightom JL, Gonsalves D, 1997. The coat protein
gene of grapevine leafroll associated closterovirus-3: cloning, nucleotide
sequencing and expression in transgenic plants.
Archives of Virology 142, 1101-1116.
Purcifull D,
Edwardson J, Hiebert E, Gonsalves D, 1984. Papaya ringspot virus.
Descriptions of Plant Viruses. No. 84. Wellesbourne, UK: Association of Applied
Biologists.
Slightom J, 1991. Custom PCR
engineering of a plant expression vector. Gene 100, 251-255.
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