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ARS Home » Pacific West Area » Corvallis, Oregon » National Clonal Germplasm Repository » Research » Publications at this Location » Publication #326729
Title: FaRXf1: a locus conferring resistance to angular leaf spot caused by Xanthomonas fragariae in octoploid strawberry

Author
item ROACH, JACK - University Of Florida
item VERMA, SUJEET - University Of Florida
item PERES, NATALIA - University Of Florida
item JAMIESON, ANDREW - Agriculture And Agri-Food Canada
item VAN DE WEG, ERIC - Wageningen University And Research Center
item BINK, MARCO - Wageningen University And Research Center
item Bassil, Nahla
item LEE, SEONGHEE - University Of Florida
item WHITAKER, VANCE - Desiderio Finamore Veterinary Research Institute (FEPAGRO)

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2016
Publication Date: 3/9/2016
Citation: Roach, J., Verma, S., Peres, N., Jamieson, A., Van De Weg, E., Bink, M.C., Bassil, N.V., Lee, S., Whitaker, V. 2016. FaRXf1: a locus conferring resistance to angular leaf spot caused by Xanthomonas fragariae in octoploid strawberry. Theoretical and Applied Genetics. 129(6):1191-1201. doi: 10.1007/s00122-016-2695-1.

Interpretive Summary: Angular leaf spot is the only major bacterial disease of cultivated strawberry and may cause reductions of up to 8 % of marketable yield in Florida winter annual production. No resistant cultivars have been commercialized but resistance is found in wild accessions US4808 and US4809. The objective of this study was to determine the mode of inheritance of resistance, to identify causal regions in the strawberry genome, and to begin incorporating resistance into Florida-adapted germplasm. Resistance was observed in two years of field trials with inoculated plants that assayed four families descended from US4808 to US4809. Results of segregation in all the families indicated control by a single gene. Using a selective genotyping approach and pedigree-based analysis, a single major-effect DNA region was identified in two families, one descended from each resistant accession. We determined the location of the region encoding both resistance sources on one of the strawberry chromosomes. Characterization of this region will facilitate marker-assisted selection toward the development of new resistant cultivars.

Technical Abstract: 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.