First Report of Rose rosette virus Associated with Rose Rosette Disease Infecting Knockout Roses in Florida

Area of Science:

• Plant Pathology
• Virology
• Horticulture

Background:

• Roses are a significant ornamental crop in the U.S., with Florida being a major producer.
• Recent years have seen increased popularity of shrub roses, including Knock Out varieties, in Florida.
• Unusual virus-like symptoms, such as witches'-broom and distorted growth, were observed on Knock Out roses.

Purpose of the Study:

• To identify the causal agent of the observed virus-like symptoms on Knock Out roses in Florida.
• To confirm the presence and genetic identity of the suspected virus.
• To assess the occurrence of other rose-infecting viruses in the symptomatic plants.

Main Methods:

• Total RNA was extracted from symptomatic and non-symptomatic rose samples.
• Reverse-transcription (RT) followed by PCR with Rose rosette virus (RRV)-specific primers was performed.
• PCR amplicons were sequenced, and BLAST analysis was conducted for identification.
• Blot hybridization assays using RRV-specific probes were performed for confirmation.
• RT-PCR was used to test for Rose cryptic virus (RCV) and Blackberry chlorotic ringspot virus (BCRV).

Main Results:

• RT-PCR assays produced a 375 bp amplicon exclusively in symptomatic samples, confirming RRV presence.
• Sequencing and BLAST analysis revealed 99% identity to known RRV strains.
• Blot hybridization assays further confirmed RRV in all eight symptomatic samples.
• The eriophyid mite vector, Phyllocoptes fructiphilus, was not detected in the examined samples.
• Samples tested negative for RCV and BCRV.

Conclusions:

• This study confirms the association of Rose rosette virus (RRV) with symptomatic Knock Out roses in Florida.
• This is the first documented occurrence of RRV in roses within the state of Florida.
• The findings highlight the urgent need for quarantine and management strategies to protect Florida's economically important rose industry from RRV.