Cape gooseberry (Physalis peruviana) was first reported as a host of Potato spindle tuber viroid (PSTVd) in 2009 (4). In Slovenia, 10 young plants of cape gooseberry that were grown in a glasshouse were inspected in April 2011. Plants were multiplied from an adult plant of unknown origin. During sampling, the inspected plants showed no disease symptoms. Total RNA was extracted twice from leaves of five plants with an RNeasy Plant Mini Kit (QIAGEN, Hilden, Germany). Reverse transcription (RT)-PCR assay employing two pairs of semi-universal pospiviroid primers (Pospi1-RE/FW and Vid-RE/FW ) yielded amplicons of the expected size (approximately 196 and 360 bp) from each total RNA preparation. All four DNA products were sequenced directly (Macrogen, Amsterdam, the Netherlands). Sequence analysis confirmed the identity of a viroid as PSTVd. Further RT-PCRs using primer pairs of Shamloul et al. (2) and Di Serio (1) were made to obtain a full viroid sequence. The sequence was deposited in the NCBI GenBank under Accession No. JN543964. Sequence analysis confirmed the identity of the viroid as PSTVd. The Slovenian isolate had 358 nucleotides and was 100% identical to the cape gooseberry isolate from Germany (GenBank Accession No. EU862231) and the tomato isolate from New Zealand (GenBank Accession No. AF369530). The analyzed sample was the only sample of cape gooseberry taken from the start of the survey for PSTVd in 2006 because P. peruviana is rarely grown in Slovenia. To our knowledge, this is the first report of PSTVd infection of P. peruviana in Slovenia and the fourth reported case after the detection of PSTVd infection in Germany, Turkey, and New Zealand. This emerging host for PSTVd could potentially serve as a source of infection for tomato and potato, where the viroid can cause severe losses.
References: (1) F. Di Serio. J. Plant Pathol. 89:297, 2007. (2) A. M. Shamloul et al. Can. J. Plant Pathol. 19:89, 1997. (3) J. Th. J. Verhoeven et al. Eur. J. Plant Pathol. 110:823, 2004. (4) J. Th. J. Verhoeven et al. Plant Dis. 93:316, 2009.