A research collaboration between the BC Blueberry Council, Simon Fraser University (SFU), and Phyto Diagnostics Company Ltd., supported by Genome BC, has identified why standard diagnostic tests have sometimes failed to detect viruses in visibly sick blueberry plants. The findings are expected to support the development of updated tools for growers.
British Columbia produces more than 90 percent of Canada's highbush blueberries, a crop that in 2019 was the province's highest-value agricultural export. Two main viral threats to blueberry production are Blueberry Scorch Virus and Blueberry Shock Virus. Both affect plants but are not harmful to humans. Plants infected with Scorch cannot recover and must be removed, while those affected by Shock can recover over time. Because both viruses cause similar symptoms, growers rely on the standard ELISA (Enzyme-Linked Immunosorbent Assay) test to distinguish between them.
© Genome British Columbia
In recent years, however, some plants showing symptoms tested negative for both viruses. "We took hundreds of samples from fields in the Fraser Valley in 2020, and up to 30 percent of sick plant samples came back negative for the viruses that are known to affect blueberry bushes. These inconclusive results led to uncertainty for our farmers," said Dr. Eric Gerbrandt, Research Director at the BC Blueberry Council and project co-lead.
To address the problem, the research team, led by Dr. Jim Mattsson of SFU's Department of Biological Sciences, used genomic sequencing to analyze samples from infected plants across BC. The sequencing revealed that existing Shock and Scorch viruses had evolved into new variants, explaining why standard ELISA tests had failed to detect them. Four previously undetected viruses were also identified, though researchers determined they do not cause disease in blueberries and are not a threat to growers.
Based on these findings, updated diagnostic tools are being developed. These include an improved ELISA test for new viral variants and more sensitive PCR tests capable of detecting lower levels of Shock and Scorch viruses. The PCR tests are intended to supplement ELISA testing, particularly for checking young plants before they are established in new fields.
"These viruses are one of the most economically significant challenges we face, and this work has helped bring the importance of viruses to growers' attention so they can better manage infected fields," Gerbrandt said.
The updated diagnostic tools are expected to be available for growers by the next growing season.
For more information:
Genie Tay
Genome British Columbia
Tel: +44 604 895 0663
Email: [email protected]
www.genomebc.ca