Fusarium wilt, a devastating disease caused by the soil-borne pathogen Fusarium oxysporum f. sp. fragariae, causes economic losses in strawberry (Fragaria × ananassa) worldwide. This disease was first identified in California in 2006 in fields where pre-plant fumigation with methyl bromide was no longer used. Fusarium wilt has since become a serious threat to production in California, which supplies a majority of strawberries produced in the US. A panel of 566 historically and commercially important F. × ananassa germplasm accessions were phenotyped for resistance in 2016 and 2017 by artificially inoculating field-grown plants with spores of a virulent isolate of F. oxysporum f.sp. fragariae found in California (AMP132) and were genotyped with 38,506 single-nucleotide polymorphisms (SNPs) using the iStraw35 Affymetrix Axiom array. In both years, Fusarium wilt resistance had high repeatability (0.983 and 0.896 in 2016 and 2017 respectively). Genome-wide association mapping using a diploid Fragaria vesca reference genome (v4.0) identified statistically significant (-log10(p-value) > 9) SNPs occurring in a 3 Mb region on chromosome 2 in both years, with these SNPs in linkage disequilibrium with resistance phenotypes. Genetic mapping in two self-pollinated mapping populations confirmed Mendelian segregation of a single dominant resistance gene. This R-gene, FoR2U-1, traces to early cultivars, predates the appearance of the disease in California by decades, and appears to provide strong resistance to the F. oxysporum isolate AMP132.
|Advisor:||Knapp, Steven J.|
|Commitee:||Brummer, Edward C., Gordon, Thomas R.|
|School:||University of California, Davis|
|Department:||Horticulture and Agronomy|
|School Location:||United States -- California|
|Source:||MAI 57/01M(E), Masters Abstracts International|
|Subjects:||Horticulture, Plant sciences, Plant Pathology|
|Keywords:||Fusarium, Oxysporum, Resistance, Strawberry|
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