Sequence comparison and transmission of <Emphasis Type="Italic">Blackcurrant reversion virus</Emphasis> isolates in black,red and white currants with black currant reversion disease and full blossom disease symptoms

We collected samples from black, red and white currants showing symptoms of blackcurrant reversion disease (BRD) and full blossom disease (FBD), cultivated in the Czech Republic. Blackcurrant reversion virus (BRV) was detected in all symptomatic plants. After amplification, a substantial part of the 3′ non-translated region (3′-NTR) of RNA2 of 15 new isolates of BRV was sequenced and compared with sequences available in the literature and GenBank. We did not find significant sequence diversity among isolates associated with either FBD or BRD. BRV was graft-transmitted from FBD infected red currant to black currant where symptoms of BRD were observed. Further sequence analysis of BRV isolates resulted in a phylogenetic tree with four branches, each consisting of six to nine isolates. No correlation with geographic origin was visible on the tree as isolates from various countries occurred in all four branches. We also found no correlation between the host and the topology of the tree: most of black currant isolates occurred in branches 3 and 4, but also occurred in branches 1 and 2. Only one white currant and one red currant isolate occurred in branches 3 and 4, respectively. The sequence identity of the Czech isolates in this region ranged from 91.9 to 99.8%. The 17 plant species growing within and in the close vicinity of the BRD-infested plantation were tested negative for BRV by RT-PCR as natural hosts of BRV. BRV was successfully transmitted by mechanical inoculation from black currant to Nicotiana occidentalis and N. tabacum cv. Xanthi, the latter being a new host for BRV. The infection was confirmed by PCR and sequencing.     

Cytokinin, auxin, and abscisic acid dynamics during flower development in white and red currants infected with Blackcurrant reversion virus

Blackcurrant reversion virus (BRV) infection, characteristic by flower malformation, resulted at the early flower stage in elevated levels of bioactive cytokinins and their biosynthetic precursors in flowers of white currant ‘Blanka’ and red currant ‘Vitan’. In healthy flowers, flower-to-berry transition was accompanied by an increase in bioactive cytokinins that was not observed in infected flowers, which were incapable of further development. Auxin levels increased during flower development, in ‘Vitan’ only in flowers with normal morphology (both healthy and infected). BRV infection did not have a significant effect on cytokinin or auxin levels in the leaves of either cultivar, it coincided with a mild elevation in the content of abscisic acid in the flowers of both cultivars.     

A possible relationship between viral infection and chromosome damage in breeding boars

A cytogenetic analysis of peripheral blood lymphocytes was carried out on breeding boars (n = 5) on a farm where viral infections (porcine parvovirosis) had occurred. Several different types of chromosomal aberrations were observed including chromatid breaks (23.60 +/- 2.88%), exchanges (9.60 +/- 8.99%), and fragments (4.26 +/- 3.31%). In addition, 2.94 +/- 1.74% of cells in metaphase showed pulverization. Cells with multiple aberrations were seen in two of five boars. The chromosomal damage in the boars may have been induced by a genotoxic agent such as a viral infection, and may also be related to the reproductive impairment of the pigs.