Potato spindle tuber viroid detected on ornamental Solanaceae in Italy
In Italy, a limited survey on the occurrence of Potato spindle tuber viroid (Pospiviroid, PSTVd – EPPO A2 List) in ornamental Solanaceae was conducted at the beginning of 2007. A total of 23 symptomless Solanum jasminoides plants were collected at random from 4 nurseries in Central and Southern Italy. Molecular tests were performed (RT-PCR, dot-blot hybridization, sequencing) and revealed the presence of PSTVd in 17 samples of S. jasminoides. The study was extended to 2 plants of S. rantonnetii growing in one of the nurseries surveyed and 1 plant tested positive. This was the first record of a natural infection of PSTVd in S. rantonnetii. As these preliminary studies stressed the need for simple, fast and economic diagnostic methods, a tissue-printing hybridization method was developed. To validate it, 94 samples of S. jasminoides and 106 samples of S. rantonnetii were collected from 3 glasshouses in Apulia. The incidence of PSTVd was 100 % in S.;jasminoides and 26.4% in S. rantonnetii (all plants were symptomless). Identical results were obtained when the same samples were tested by dot-blot hybridization and RT-PCR. The identity of the pathogen was also confirmed by sequencing PCR-products obtained from 5 samples. Although further studies have to be done, in particular on the specificity of the method, tissue-printing hybridization could be a useful tool for the routine detection of PSTVd in ornamental Solanaceae. Although limited to a small number of plants and localities, these preliminary studies have revealed a very high percentage of infected plants which underlines the need for large scale surveys in Italy and other European countries on the occurrence of PSTVd in ornamental plants, and the need to produce propagation material free of PSTVd.
Sources
Di Serio F (2007) Identification and characterization of Potato spindle tuber viroid infecting Solanum jasminoides and S. rantonnetii in Italy. Journal of Plant Pathology 89(2), 297-300.
Di Serio F, Silletti MR, Trisciuzzi VN, Guario A, Percoco A, Lillo AR (2007) [Potato spindle tuber viroid in ornamental Solanaceae and its detection by tissue printing hybridization assay.] Informatore Fitopatologico no. 12, 82-85 (in Italian).