Abstract:
Citrus, comprising of mandarins, sweet oranges, grapefruit, limes and
lemons are the most important fruit crops grown in Sri Lanka. Among virus
diseases Citrus tristeza virus (CTV) causes drastic losses of yields. CTV
belongs to the genus Colesterovirus, is a flexuous rod virus with dimensions
of 2000 nm in length and 12 nm in diameter. Department of Agriculture
has released few mandarin varieties. Among that “Indu” plays a major role
in cultivation due to its more favorable characters. Identification of the
vector of CTV for “Indu” is essential for the disease management. CTV
infected “Indu” mandarin was indexed by direct antigen coating Enzyme Linked Immunosorbent Assay (Dac-ELISA). Total RNA extraction was
done by using silica fractionated method. CTV positive plant samples and
the aphids which were fasted and fed with CTV infected leaves were
amplified to Reverse Transcriptase Polymerase Chain Reaction (RT- PCR)
by using reverse primer CTV_AR18R and for PCR, CTV_AR18F and
CTV_AR 18R primers were used. These primers target polyprotein 18 gene
of the virus genome. It was observed that optimum annealing temperature
was 600C for both, plant samples and aphids. PCR products with
approximately 570 bp were obtained on agarose gel. It showed that
Toxoptera auranti is a potential vector of CTV in the wet zone of Sri Lanka.
