Potato spindle tuber viroid (PSTVd) has been recently found in many solanaceous ornamental plant species. This study reports on the effectiveness of mechanical transmission between Brugmansia suaveolens, Solanum jasminoides, potato and tomato. Inoculation with 'infected' plant sap diluted in water, rubbing with contaminated finger tips and cutting with contaminated razor blades all resulted in transmission of PSTVd. Temperature, plant species and source of inoculum were found to be critical factors. An average temperature of 15°C only resulted in a few infections, whereas transmission at 20 and 25°C was more successful. Tomatoes were more susceptible to PSTVd than B. suaveolens, S. jasminoides and potatoes. Furthermore, S. jasminoides was a better source of inoculum than B. suaveolens. No transmission was obtained after repeated addition of inocula to tomato roots. These results indicate that PSTVd can be transmitted between plant species in practice by crop handling.

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High-throughput sequencing (HTS) technologies have become indispensable tools assisting plant virus diagnostics and research thanks to their ability to detect any plant virus in a sample without prior knowledge. As HTS technologies are heavily relying on bioinformatics analysis of the huge amount of generated sequences, it is of utmost importance that researchers can rely on efficient and reliable bioinformatic tools and can understand the principles, advantages, and disadvantages of the tools used. Here, we present a critical overview of the steps involved in HTS as employed for plant virus detection and virome characterization. We start from sample preparation and nucleic acid extraction as appropriate to the chosen HTS strategy, which is followed by basic data analysis requirements, an extensive overview of the in-depth data processing options, and taxonomic classification of viral sequences detected. By presenting the bioinformatic tools and a detailed overview of the consecutive steps that can be used to implement a well-structured HTS data analysis in an easy and accessible way, this paper is targeted at both beginners and expert scientists engaging in HTS plant virome projects.

Unusual virus-like symptoms were first observed in 2001 on grapevine cvs. Pinot gris and Sauvignonasse in vineyards from the western part of Slovenia. Symptomatic plants showed shortened internodes, poor leaf development, mottling, and deformations of leaves that resulted in poor growth of symptomatic plants. In 2003 and 2004, several samples were tested for Arabis mosaic virus, Cherry leafroll virus, Grapevine fanleaf virus, Raspberry bushy dwarf virus, Strawberry latent ringspot virus, Tomato black ring virus, Tomato ringspot virus, and Tobacco ringspot virus by DAS-ELISA, but none of them could be confirmed as the cause of the observed symptoms. During intensive visual inspections between 2002 and 2006, the symptoms were observed on most grapevine cultivars grown in the Primorska region but predominantly on the two previously mentioned cultivars. In Trentino, northern Italy, similar virus-like symptoms, i.e., chlorotic mottling, puckering and deformation of the leaves, reduced yield, and low quality of the berries were observed in grapevine plants cv. Pinot gris in 2003 and in cvs. Traminer and Pinot noir in 2009 (2). No common grapevine viruses could be associated with the disease. In 2012, a new trichovirus named Grapevine Pinot gris virus (GPGV) was found in Pinot gris plants using deep sequencing. The virus was also detected in symptomless plants (2). GPGV was later reported also from Korea causing inner necrosis of berries and poor fruit set in grapevine cv. Tamnara (1). In 2012, 42 leaf samples from mostly symptomatic grapevine plants of cvs. Pinot gris, Pinot noir, and Muscat blanc were collected at three locations in the Primorska region. Total RNA was extracted from leaves using the MagMAX Express magnetic particle processor with MagMAX-96 Total RNA Isolation Kit and Plant RNA Isolation Aid in Lysis Binding Solution Concentrate (all by Life Technologies, Grand Island, NY). DNA fragments of 1,049 bp corresponding to the movement protein gene were successfully amplified by RT-PCR from 40 samples using primers GPgV5619 and GPgV6668 (2). Amplification products from three plants were cloned into the pGEM-T Easy vector (Promega, Madison, WI) and sequenced. The sequences were deposited in the EBI database under the accession numbers HG738850 to 52. All the nucleotide sequences shared 97.4 to 97.6% identity with GPGV from Italy (sequence FR877530) and 97.1 to 98.2% amino acid identity within the translated region. To our knowledge, this is the first report of GPGV in Slovenia. The disease seems to be spreading extensively in the Primorska region, causing considerable economic losses, and in 2013 it was also observed in other regions of Slovenia. Since the virus could be found in symptomless plants in Italy and in Slovenia, its role in the development of the disease should be further investigated. References: (1) I. S. Cho et al. New Dis. Rep. 27:10, 2013. (2) A. Giampetruzzi et al. Virus Res. 163:262, 2012.

Five isolates of a new member of the family Closteroviridae, tentatively named blackcurrant leafroll-associated virus 1 (BcLRaV-1), were identified in the currant. The 17-kb-long genome codes for 10 putative proteins. The replication-associated polyprotein has several functional domains, including papain-like proteases, methyltransferase, Zemlya, helicase, and RNA-dependent RNA polymerase. Additional open reading frames code for a small protein predicted to integrate into the host cell wall, a heat-shock protein 70 homolog, a heat-shock protein 90 homolog, two coat proteins, and three proteins of unknown functions. Phylogenetic analysis showed that BcLRaV-1 is related to members of the genus Closterovirus, whereas recombination analysis provided evidence of intraspecies recombination.