Tracking Plum pox virus in Chile throughout the year by three different methods and molecular characterization of Chilean isolates

During 2007, a survey was performed to detect and identify Plum pox virus (PPV) in Chilean stone fruit commercial orchards. A total of 1396 trees were analyzed and 45 (3.22 %) of them resulted positive. A fragment of 467 bp, corresponding to the replicase-coat protein (Nib-CP) region from the virus genome, was amplified and the the sequences obtained permitted the characterization of all isolates as PPV-D type, confirming that, so far, this is the only serotype present in Chile. To optimize virus detection, 27 PPV-positive trees were selected and sampled monthly from December 2006 until December 2007, collecting plant tissues available at the time of sampling (leaves, cuttings, buds and flowers). Each sample was analyzed by three different techniques: DASI-ELISA, RT-PCR and non-isotopic molecular hybridization (MH). The results showed that RT-PCR was more sensitive for detection in all months excepting January 2007, when the three techniques showed the same sensitivity. In general, MH showed a better sensitivity compared with DASI-ELISA. The best plant materials for analysis were: leaves, in February, March, September and October; phloem from cuttings in June; buds in July, and flowers in August.