Detection of Blueberry red ringspot virus in highbush blueberry cv. ‘Coville’ in Slovenia

Blueberry red ringspot virus (BRRSV) infects blueberries and is present in USA. It causes red ringspots or red blotches on one year old stems or older. In mid- to late summer reddish-brown spots develop on older leaves. In some blueberry cultivars also fruit symptoms, circular areas of light colour and/or fruit deformations, can be seen. In spring 2008 BRRSV was detected in symptomatic bark from blueberry cv. ‘Coville’ showing typical BRRSV symptoms. The obtained PCR product was sequenced and the identity of the virus confirmed. To our knowledge this was the first finding of BRRSV in Slovenia.Keywords: BRRSV, Vaccinium, PCR, detectio

Comparison of Raspberry bushy dwarf virus isolates from Hungary and Slovenia

In 2006 and 2007 samples of grapevine and Rubus species were collected and analysed by DAS-ELISA to survey the presence of Raspberry bushy dwarf virus (RBDV) in Slovenia and Hungary. Seven varieties of raspberry from one Hungarian collection orchard were found to be infected. In Slovenia the presence of RBDV was confirmed only in three samples of wild Rubus. None of the 133 samples from different locations in Hungary proved to be infected with RBDV, although this virus is found to be widely distributed in grapevine in neighbouring Slovenia. Serological characterisation with three monoclonal antibodies (R2, R5 and D1) was performed on positive samples. Selected positive samples were partially sequenced. The results of serological and molecular analyses were compared with the analyses of raspberry and grapevine isolates obtained in Slovenia from other projects and published RBDV sequences from the GeneBank database to study the variability among hosts and locations. Isolates from grapevine grouped separately from the black raspberry isolate and all the red raspberry isolates. RBDV isolates from Hungarian samples formed a subgroup within red and black raspberry group.Keywords: RBDV, variability, Rubus, raspberry, grapevine, sequences, monoclonal antibodie

An outbreak of Potato spindle tuber viroid in tomato is linked to imported seed

In 2011, an outbreak of the quarantine-regulated pathogen Potato spindle tuber viroid (PSTVd) occurred in a commercial glasshouse-grown tomato crop in Queensland, Australia. Phylogenetic studies showed that the genotype of this isolate grouped in a cluster of PSTVd genotypes from tomato and Physalis peruviana, and exhibited an interesting mutation (U257→A) that has previously been linked to lethal symptom expression in tomato. Transmission studies showed that the viroid could be mechanically transmitted from crushed fruit sap, but not from undamaged fruits. A low rate of asymptomatic infection was determined for plants in the affected glasshouse, demonstrating the efficacy of using symptoms to detect PSTVd infections in tomato. No PSTVd infections were detected in solanaceous weeds located outside of the infected glasshouse, excluding them from playing a role in the viroid epidemiology. Monitoring and subsequent testing of new tomato crops grown in the facility demonstrated successful eradication of the pathogen. A trace-back analysis linked the outbreak of PSTVd to an infected imported tomato seed-lot, indicating that PSTVd is transmitted internationally through contaminated seed

Molecular characterization of the coat protein gene of prunus necrotic ringspot virus infecting peach in Montenegro

In 2011 and 2012, two major peach-growing areas in Montenegro were surveyed for the occurrence of eleven peach viruses. Samples collected from 105 peach and nectarine trees were tested by Reverse transcription-polymerase chain reaction (RT-PCR) using sets of primers specific for the detection of Apple chlorotic leaf spot virus (ACLSV), Apple mosaic virus (ApMV), Cherry mottle leaf virus (CMLV), Prunus necrotic ringspot virus (PNRSV), Prune dwarf virus (PDV), Peach mosaic virus (PMV), Peach rosette mosaic virus (PRMV), Tobacco ringspot virus (TRSV) and Tomato ringspot virus (ToRSV). The occurrence of Strawberry latent ringspot virus (SLRSV) was examined using nested RT-PCR, while a Real-time quantitative RT-PCR method was applied for detection of Plum pox virus (PPV). PPV, PNRSV and PDV were detected in 42.9, 24.8 and 0.9 % of samples. Mixed viral infections were recorded in 6.7 % of samples, while results showed the absence of ACLSV, ApMV, PMV, CMLV, SLRSV, PRMV, TRSV and ToRSV from all assayed samples. In particular, the PCR products of complete coat protein (CP) gene was cloned and sequenced from fourteen PNRSV isolates. A high identity (87.5–100 %) was found between CP nucleotide sequences of Montenegrin isolates and other PNRSV isolates from different hosts and geographic regions retrieved from GenBank. CP nucleotide sequence comparison, as well as phylogenetic reconstruction confirmed the clustering of the isolates into three molecular groups (PV-96, PV-32 and PE-5), whereby Montenegrin isolates were separated into two phylogroups (PV-96 and PE-5). Comparative sequence and phylogenetic analysis showed that clustering of various isolates was not associated with geographic and host origin

The role of Schmidt 'Antonovka' in apple scab resistance breeding

'Antonovka' has long been recognised as a major source of scab (Venturia inaequalis) resistance useful for apple breeding worldwide. Both major gene resistances in the form of the Rvi10 and Rvi17 and quantitative resistance, collectively identified as VA, have been identified in different accessions of 'Antonovka'. Most of the 'Antonovka' scab resistance used in apple-breeding programmes around the world can be traced back to Schmidt 'Antonovka' and predominantly its B VIII progenies 33,25 (PI 172623), 34,6 (PI 172633), 33,8 (PI 172612) and 34,5 (PI 172632). Using genetic profile reconstruction, we have identified "common 'Antonovka' " as the progenitor of the B VIII family, which is consistent with it having been a commercial cultivar in Poland and the single source of scab resistance used by Dr. Martin Schmidt. The major 'Antonovka' scab resistance genes mapped to date are located either very close to Rvi6, or about 20-25 cM above it, but their identities need further elucidation. The presence of the 139 bp allele of the CH-Vf1 microsatellite marker known to be associated with Rvi17 (Va1) in most of the 'Antonovka' germplasm used in breeding suggests that it plays a central role in the resistance. The nature and the genetic relationships of the scab resistance in these accessions as well as a number of apple cultivars derived from 'Antonovka', such as, 'Freedom', 'Burgundy' and 'Angold', are discussed. The parentage of 'Reglindis' is unclear, but the cultivar commercialised as 'Reglindis' was confirmed to be an Rvi6 cultivar