Cloning, sequencing, and promoter identification of Blueberry red ringspot virus, a member of the family Caulimoviridae with similarities to the "Soybean chlorotic mottle-like" genus.

The double-stranded DNA genome of Blueberry red ringspot virus (BRRV), a member of the family Caulimoviridae, was cloned and sequenced. The genome organization and relationships of the 8303 nt sequence revealed BRRV to be a tentative member of the genus that has been provisionally named "Soybean chlorotic mottle-like viruses", rather than a member of the genus Caulimovirus, in which it had been placed previously. Insertion of the putative 35S promoter homolog of BRRV into promoterless constructs carrying the UidA (beta-glucuronidase) gene resulted in high-level transient expression from cranberry and stable expression from transgenic tobacco. Sequences of 5'-RACE clones derived from transcripts from transgenic tobacco were consistent with the map position of the promoter.

Cloning and sequencing of peach rosette mosaic virus RNA1.

The complete nucleotide sequence of peach rosette mosaic nepovirus (PRMV) RNA1 has been determined. A grapevine isolate of PRMV from Michigan was propagated and purified and cDNA clones representing 99. 5% of the RNA1 were constructed. The cDNA and direct RNA sequence analysis revealed a RNA species of 8004 nucleotides, excluding a 3' polyadenylated tail. The 5'- and 3'-untranslated regions were 52 and 1474 nucleotides, respectively. Computer analysis of the PRMV RNA1 nucleotide sequence unveiled a single long open reading frame of 6477 nucleotides, which is capable of encoding a 240 kDa polyprotein. Analysis of the predicted amino acid sequence of RNA1 revealed amino acid motifs characteristic of a replicase, proteinase, NTP-binding protein and a proteinase cofactor. The order and identity of these putative proteins are consistent with other nepoviruses. Analysis of PRMV RNA1 further distinguishes the taxonomic subdivisions within the nepovirus group, confirms the subgroup three status of PRMV and lays the groundwork for a replicase-mediated resistance strategy.

An Anatomical Study of Prune Brown Line Disease and Immuno-localization of Tomato Ringspot Virus in Plum Bark.

Bark from the graft union of tomato ringspot virus (ToRSV) infected plum, symptomatic for brown line disease, showed anatomical changes characteristic of the wound response process. The wound tissue consisted of necrotic cells demarcated by pinkish purple necrophylactic periderm, whose function is to protect living tissues from detrimental effects associated with necrosing cells. However, formation of gray exophylactic periderm led to the sloughing off of the wound tissue and the necrophylactic periderm, resulting in discontinuity of the exophylactic periderm and secondary virus invasion into the wound site. The changes seen in the bark suggest that the hypersensitive response in plum rootstock bark to ToRSV is slow, allowing a systemic movement of the virus and development of a brown line (BL) along the scion and rootstock union. Necrophylactic periderm was not seen in the bark from the graft union of a healthy plum tree. In the graft union of a plum tree without a BL, but testing ToRSV-positive in the roots, localized areas of wound tissue with pinkish purple necrophylactic periderm developed only in the rootstock portion of the tree. Silver-enhanced protein A-colloidal gold immunolabeling was seen on the cell wall and in the cytoplasm of bark tissue from the BL region of scion and rootstock and leaves from the rootstock suckers.