Identification, Characterization, and Detection of Black raspberry necrosis virus

Area of Science:

• Plant Pathology
• Virology
• Molecular Biology

Background:

• A serious disease causing rapid decline and death in black raspberry (Rubus occidentalis) was observed in Oregon.
• Symptomatic plants exhibited mosaic symptoms, indicating a potential viral etiology.

Purpose of the Study:

• To identify and characterize the causal agent of the black raspberry decline disease.
• To develop a diagnostic method for the identified virus and determine its association with disease symptoms.

Main Methods:

• Double-stranded RNA extraction from symptomatic plants.
• Cloning and sequencing of viral RNA to determine genome organization and identify novel viruses.
• Development of a reverse-transcriptase polymerase chain reaction (RT-PCR) test for virus detection.
• Phylogenetic analysis to determine viral taxonomic placement.

Main Results:

• A novel virus, tentatively named Black raspberry decline-associated virus (BRDaV), was identified with two genomic RNAs (7,581 and 6,364 nucleotides).
• BRDaV shares genome organization with Strawberry mottle virus (genus Sadwavirus), with a unique C-terminal domain in RNA 1 poly-protein potentially involved in DNA repair.
• BRDaV was consistently associated with decline symptoms, and RT-PCR confirmed its presence in affected Rubus tissue.
• BRDaV was concluded to be a strain of Black raspberry necrosis virus (BRNV), a previously described but unsequenced virus.
• The North American strain of BRNV is non-persistently vectored by large raspberry and green peach aphids.

Conclusions:

• Black raspberry decline-associated virus (BRDaV) is identified as a strain of Black raspberry necrosis virus (BRNV).
• BRNV, belonging to the genus Sadwavirus, is confirmed as the causal agent of a serious disease affecting black raspberries.
• The findings provide a basis for developing management strategies against BRNV through understanding its transmission and genetic makeup.