Development of PCR Based Methods to Reliably Distinguish Shock or Scorch Virus

Title: Development of PCR-Based Methods to Reliably Distinguish Shock or Scorch Virus-Infected Blueberry Plants.

Principal Investigator: Dr. Jim Mattsson, Simon Fraser University

Duration: April 1, 2020 to March 31, 2021

Project Summary:

Blueberry Shock Virus (BlShV) and Blueberry Scorch Virus (BlScV) are widespread in the Pacific Northwest as well as British Columbia.  Symptoms of BlShV and BlScV are initially very similar (i.e., sudden leaf and flower necrosis during the bloom period).  Blueberry bushes infected with BlScV will die over the course of one or more years after first showing symptoms, and aphid transmission of this virus necessitates removal of plants from the field to prevent spread of the disease.  However, BlShV-infected plants produce a second flush of leaves and appear normal by late summer, and plants of most cultivars recover completely by the following year.  Therefore, plants infected with this second virus, which is transmitted by pollen, are not typically removed from the field.

These viruses are distinguished using a lab-based test, which is then used to direct management decisions by growers.  A current problem is that this lab test is showing false negatives, meaning that plants with visual virus symptoms are testing negative for both viruses.  There are a few potential reasons for these false negatives, and this project aims to improve the current diagnostic tools to reliably distinguish BlScV and BlShV so that growers can efficiently control the these two virual diseases.

Objectives:

1. To characterize BlScV and BlShV coat protein genes from plant samples collected across a range of blueberry farms in BC;
2. To identify different virus strains and evaluate their impact on current detection methods; and

To improve diagnostic testing methodologies for both BlScV and BlShV.