title: Genetic mapping, synteny, and physical location of two loci forFusarium oxysporumf. sp.tracheiphilumrace 4 resistance in cowpea [Vignaunguiculata(L.) Walp].
abstract: Fusarium wilt is a vascular disease caused by the fungusFusariumoxysporumf.sp.tracheiphilum(Fot) in cowpea [Vignaunguiculata(L.) Walp]. In this study, we mapped loci conferring resistance to Fot race 4 in three cowpea RIL populations: IT93K-503-1 × CB46, CB27 × 24-125B-1, and CB27 × IT82E-18/Big Buff. Two independent loci which confer resistance to Fot race 4 were identified,Fot4-1andFot4-2.Fot4-1was identified in the IT93K-503-1 (resistant) × CB46 (susceptible) population and was positioned on the cowpea consensus genetic map, spanning 21.57-29.40 cM on linkage group 5. TheFot4-2locus was validated by identifying it in both the CB27 (resistant) × 24-125B-1 (susceptible) and CB27 (resistant) × IT82E-18/Big Buff (susceptible) populations.Fot4-2was positioned on the cowpea consensus genetic map on linkage group 3; the minimum distance spanned 71.52-71.75 cM whereas the maximum distance spanned 64.44-80.23 cM. These genomic locations ofFot4-1andFot4-2on the cowpea consensus genetic map, relative toFot3-1which was previously identified as the locus conferring resistance to Fot race 3, established that all three loci were independent. TheFot4-1andFot4-2syntenic loci were examined inGlycine max, where several disease-resistance candidate genes were identified for both loci. In addition,Fot4-1andFot4-2were coarsely positioned on the cowpea physical map.Fot4-1andFot4-2will contribute to molecular marker development for future use in marker-assisted selection, thereby expediting introgression of Fot race 4 resistance into future cowpea cultivars.
authors.affiliation: Department of Botany and Plant Sciences, University of California Riverside, Riverside, CA USA.
authors.forename: Marti O
authors.initials: MO
authors.lastname: Pottorff
authors.affiliation: Zhejiang Academy of Agricultural Sciences, Hangzhou, People's Republic of China.
authors.forename: Guojing
authors.initials: G
authors.lastname: Li
authors.affiliation: Department of Botany and Plant Sciences, University of California Riverside, Riverside, CA USA ; Bill and Melinda Gates Foundation, Seattle, WA USA.
authors.forename: Jeffery D
authors.initials: JD
authors.lastname: Ehlers
authors.affiliation: Department of Botany and Plant Sciences, University of California Riverside, Riverside, CA USA.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Close
authors.affiliation: Department of Nematology, University of California Riverside, Riverside, CA USA.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Roberts
keywords: Candidate genes; Cowpea; Disease resistance; Fusarium wilt; Genomics; Synteny