FaRXf1: a locus conferring resistance to angular leaf spot caused by Xanthomonas fragariae in octoploid strawberry

• Published in: Theoretical and applied genetics Vol. 129; no. 6; pp. 1191 - 1201
• Main Authors: Roach, Jack A., Verma, Sujeet, Peres, Natalia A., Jamieson, Andrew R., van de Weg, W. Eric, Bink, Marco C. A. M., Bassil, Nahla V., Lee, Seonghee, Whitaker, Vance M.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-06-2016; Springer; Springer Nature B.V
• Subjects: Agriculture; Biochemistry; Biomedical and Life Sciences; Biometris; Biometris (PPO/PRI); Biotechnology; Chromosome Mapping; Disease Resistance - genetics; Diseases and pests; DNA, Plant - genetics; Fragaria; Fragaria - genetics; Fragaria - microbiology; Fragaria ananassa; Fruits; Gene loci; Genetic Linkage; Genetic Markers; Genotype; Germplasm; Haplotypes; Health aspects; Host-bacteria relationships; Humidity; Inheritances; Life Sciences; Observations; Original Article; Pathogens; PE&RC; Pedigree; Phenotype; Plant Biochemistry; Plant Breeding/Biotechnology; Plant Diseases - genetics; Plant Diseases - microbiology; Plant Genetics and Genomics; Plant immunology; Polymorphism, Single Nucleotide; Polyploidy; Prevention; Proteobacteria; Quantitative Trait Loci; Strawberries; Winter; Xanthomonas; Xanthomonas fragariae; Canada; Netherlands; Minnesota; Florida; United States > US; Diseased Leaf Area; Selective Genotyping; Angular Leaf Spot; Overhead Irrigation; Resistant Progeny
• ISSN: 0040-5752; 1432-2242
• DOI: 10.1007/s00122-016-2695-1

Key message
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.