title: Genetic and physical mapping of candidate genes for resistance to Fusarium oxysporum f.sp. tracheiphilum race 3 in cowpea [Vigna unguiculata (L.) Walp].
abstract: Fusarium oxysporum f.sp. tracheiphilum (Fot) is a soil-borne fungal pathogen that causes vascular wilt disease in cowpea. Fot race 3 is one of the major pathogens affecting cowpea production in California. Identification of Fot race 3 resistance determinants will expedite delivery of improved cultivars by replacing time-consuming phenotypic screening with selection based on perfect markers, thereby generating successful cultivars in a shorter time period. Resistance to Fot race 3 was studied in the RIL population California Blackeye 27 (resistant) x 24-125B-1 (susceptible). Biparental mapping identified a Fot race 3 resistance locus, Fot3-1, which spanned 3.56 cM on linkage group one of the CB27 x 24-125B-1 genetic map. A marker-trait association narrowed the resistance locus to a 1.2 cM region and identified SNP marker 1_1107 as co-segregating with Fot3-1 resistance. Macro and microsynteny was observed for the Fot3-1 locus region in Glycine max where six disease resistance genes were observed in the two syntenic regions of soybean chromosomes 9 and 15. Fot3-1 was identified on the cowpea physical map on BAC clone CH093L18, spanning approximately 208,868 bp on BAC contig250. The Fot3-1 locus was narrowed to 0.5 cM distance on the cowpea genetic map linkage group 6, flanked by SNP markers 1_0860 and 1_1107. BAC clone CH093L18 was sequenced and four cowpea sequences with similarity to leucine-rich repeat serine/threonine protein kinases were identified and are cowpea candidate genes for the Fot3-1 locus. This study has shown how readily candidate genes can be identified for simply inherited agronomic traits when appropriate genetic stocks and integrated genomic resources are available. High co-linearity between cowpea and soybean genomes illustrated that utilizing synteny can transfer knowledge from a reference legume to legumes with less complete genomic resources. Identification of Fot race 3 resistance genes will enable transfer into high yielding cowpea varieties using marker-assisted selection (MAS).
authors.affiliation: Department of Botany & Plant Sciences, University of California Riverside, Riverside California, United States of America.
authors.forename: Marti
authors.initials: M
authors.lastname: Pottorff
authors.forename: Steve
authors.initials: S
authors.lastname: Wanamaker
authors.forename: Yaqin Q
authors.initials: YQ
authors.lastname: Ma
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Ehlers
authors.forename: Philip A
authors.initials: PA
authors.lastname: Roberts
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Close
mesh_terms: D001483:Base Sequence; D001947:Breeding; D002874:Chromosome Mapping; D022202:Chromosomes, Artificial, Bacterial / Q000235:genetics; D032461:Chromosomes, Plant; D020451:Contig Mapping; D060467:Disease Resistance / Q000235:genetics*; D007887:Fabaceae / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D005670:Fusarium / Q000276:immunology*; D017343:Genes, Plant; D005819:Genetic Markers; D058977:Molecular Sequence Annotation; D010641:Phenotype; D010935:Plant Diseases / Q000382:microbiology*; D020641:Polymorphism, Single Nucleotide; D026801:Synteny
chemical_list: D005819:Genetic Markers