Skip to main content
ARS Home » Pacific West Area » Davis, California » Crops Pathology and Genetics Research » Research » Research Project #441217

Research Project: Paradox Walnut Canker Etiology

Location: Crops Pathology and Genetics Research

Project Number: 2032-22000-017-032-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Oct 1, 2021
End Date: Jun 1, 2022

Objective:
Identify potential pathogens associated with Paradox Canker Disease (PCD).

Approach:
Identify nucleic acid sequences from microorganisms, including viruses, that may be present in PCD-symptomatic walnut tree bark samples and absent in comparable healthy bark samples. The required symptomatic and healthy samples were preserved from a PCD graft transmission experiment and included: bark used to transmit the disease, bark into which PCD was transmitted, and control (healthy) bark. Total nucleic acids will be extracted and purified from the samples. To identify bacterial, fungal, and oomycete microorganisms that may be present in the samples, rRNA gene amplification, sequencing, and diagnostic bioinformatics will be conducted. Conduct metatranscriptomic sequencing and associated bioinformatics to identify microorganisms, including viruses, that may be present in the samples. Strategic sample extraction and purification and use of walnut and plant pathogen sequence database resources will be required to favor detection of potential pathogen sequences and exclude walnut sequences. Additional bark samples will be collected from repeat graft transmission experiments and commercial orchards affected by PCD, as needed, to confirm findings.