Location: Crop Improvement and Protection Research
Project Number: 2038-22000-019-066-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Nov 1, 2024
End Date: Jun 30, 2027
Objective:
1. Etiology
a. Genomic and phenotypic characterization of all genotypes of Fusarium oxysporum f. sp. mori and Fusarium oxysporum f. sp. fragariae.
i. Genomic characterization to determine which strains are identical
ii. Phenotypic characterization on multiple cultivars to determine which have cross-pathogenicity to the host of the other forma specialis.
2. Detection
a. Develop and release qPCR and RPA assays to detect all blackberry-pathogenic strains Fusarium oxysporum
i. Screen historic strawberry isolates collected from nurseries using new qPCR and RPA markers to determine if these strains have been present and undiagnosed.
ii. Test a library of RPA extract samples from previous years and multiple different diagnostics labs.
3. Host resistance
a. Develop marker assisted selection tools for resistance to Fusarium oxysporum f. sp. fragariae
b. Evaluate race specificity of Fusarium oxysporum f. sp. mori
Approach:
1. Etiology
a. ARS will compare whole genome sequences of Fusarium oxysporum strains to determine the number of clonal lineages of strawberry and blackberry-pathogenic strains in California.
b. Researchers will test all strains for virulence on a variety of strawberry and blackberry cultivars.
2. Detection
a. Researchers will analyze whole genome sequences to identify genetic loci specific to each group of pathogenic strains. qPCR and RPA assays will be designed around these loci and tested both on DNA from isolated strains and infected/non-infected plant samples to determine the infective potential.
3. Host resistance
a. Researchers will cross resistant and susceptible parents and screen the progeny for resistance to the newly identified Fusarium oxysporum f. sp. fragariae race 2 strain from California. Each seedling will be genotyped and genome-wide association studies used to identify genetic loci associated with resistance. Molecular assays will be designed around these validated loci to be used for marker assisted selection.
b. Select blackberry cultivars will be screened for resistance to isolates of Fusarium oxysporum f. sp. mori
