title: FaRXf1: a locus conferring resistance to angular leaf spot caused by Xanthomonas fragariae in octoploid strawberry.
abstract: Angular leaf spot is a devastating bacterial disease of strawberry. Resistance from two wild accessions is highly heritable and controlled by a major locus on linkage group 6D. Angular leaf spot caused by Xanthomonas fragariae is the only major bacterial disease of cultivated strawberry (Fragaria ×ananassa). While this disease may cause reductions of up to 8 % of marketable yield in Florida winter annual production, no resistant cultivars have been commercialized. Wild accessions US4808 and US4809 were previously identified as resistant to the four genetic clades of X. fragariae, and introgression of the trait into commercial quality perennial-type germplasm was initiated. Previous reports indicated high heritability for the trait but proposed both single-locus and multi-locus inheritance models. The objective of this study was to determine the mode of inheritance of resistance, to identify causal loci, and to begin introgression of resistance into Florida-adapted germplasm. Resistance was observed in two years of field trials with inoculated plants that assayed four full-sib families descended from US4808 to US4809. Resistance segregated 1:1 in all families indicating control by a dominant allele at a single locus. Using a selective genotyping approach with the IStraw90 Axiom(®) SNP array and pedigree-based QTL detection, a single major-effect QTL was identified in two full-sib families, one descended from each resistant accession. High-resolution melt curve analysis validated the presence of the QTL in separate populations. The QTL was delimited to the 33.1-33.6 Mbp (F. vesca vesca v1.1 reference) and 34.8-35.3 Mbp (F. vesca bracteata v2.0 reference) regions of linkage group 6D for both resistance sources and was designated FaRXf1. Characterization of this locus will facilitate marker-assisted selection toward the development of resistant cultivars.
authors.affiliation: Department of Horticultural Science, IFAS Gulf Coast Research and Education Center, University of Florida, 14625 CR 672, Wimauma, FL, 33598, USA.
authors.forename: Jack A
authors.initials: JA
authors.lastname: Roach
authors.affiliation: Department of Horticultural Science, IFAS Gulf Coast Research and Education Center, University of Florida, 14625 CR 672, Wimauma, FL, 33598, USA.
authors.forename: Sujeet
authors.initials: S
authors.lastname: Verma
authors.affiliation: Department of Plant Pathology, IFAS Gulf Coast Research and Education Center, University of Florida, 14625 CR 672, Wimauma, FL, 33598, USA.
authors.forename: Natalia A
authors.initials: NA
authors.lastname: Peres
authors.affiliation: Atlantic Food and Horticulture Research Centre, Agriculture and Agri-Food Canada, 32 Main Street, Kentville, NS, B4N 1J5, Canada.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Jamieson
authors.affiliation: Wageningen UR Plant Breeding, P.O. Box 16, 6700AA, Wageningen, The Netherlands.
authors.forename: W Eric
authors.initials: WE
authors.lastname: van de Weg
authors.affiliation: Biometris, Wageningen University and Research Centre, P.O Box 16, 6700AA, Wageningen, The Netherlands.
authors.forename: Marco C A M
authors.initials: MC
authors.lastname: Bink
authors.affiliation: USDA-ARS, National Clonal Germplasm Repository, 33447 Peoria Road, Corvallis, OR, 97333, USA.
authors.forename: Nahla V
authors.initials: NV
authors.lastname: Bassil
authors.affiliation: Department of Horticultural Science, IFAS Gulf Coast Research and Education Center, University of Florida, 14625 CR 672, Wimauma, FL, 33598, USA.
authors.forename: Seonghee
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Horticultural Science, IFAS Gulf Coast Research and Education Center, University of Florida, 14625 CR 672, Wimauma, FL, 33598, USA. vwhitaker@ufl.edu.
authors.forename: Vance M
authors.identifier: http://orcid.org/0000-0002-2172-3019
authors.initials: VM
authors.lastname: Whitaker
mesh_terms: D002874:Chromosome Mapping; D018744:DNA, Plant / Q000235:genetics; D060467:Disease Resistance / Q000235:genetics*; D031985:Fragaria / Q000235:genetics* / Q000382:microbiology; D008040:Genetic Linkage; D005819:Genetic Markers; D005838:Genotype; D006239:Haplotypes; D010375:Pedigree; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D020641:Polymorphism, Single Nucleotide; D011123:Polyploidy; D040641:Quantitative Trait Loci; D014974:Xanthomonas
chemical_list: D018744:DNA, Plant; D005819:Genetic Markers