title: An SSR-based linkage map of yardlong bean (Vigna unguiculata (L.) Walp. subsp. unguiculata Sesquipedalis Group) and QTL analysis of pod length.
abstract: Yardlong bean (Vigna unguiculata (L.) Walp. subsp. unguiculata Sesquipedalis Group) (2n = 2x = 22) is one of the most important vegetable legumes of Asia. The objectives of this study were to develop a genetic linkage map of yardlong bean using SSR makers from related Vigna species and to identify QTLs for pod length. The map was constructed from 226 simple sequence repeat (SSR) markers from cowpea  (Vigna unguiculata (L.) Walp. subsp. unguiculata Unguiculata Group), azuki bean (Vigna angularis (Willd.) Ohwi & Ohashi), and mungbean (Vigna radiata (L.) Wilczek) in a BC(1)F(1) ((JP81610 × TVnu457) × JP81610) population derived from the cross between yardlong bean accession JP81610 and wild cowpea (Vigna unguiculata subsp. unguiculata var. spontanea) accession TVnu457. The markers were clustered into 11 linkage groups (LGs) spanning 852.4 cM in total length with a mean distance between adjacent markers of 3.96 cM. All markers on LG11 showed segregation distortion towards the homozygous yardlong bean JP81610 genotype. The markers on LG11 were also distorted in the rice bean (Vigna umbellata (Thunb.) Ohwi & Ohashi) map, suggesting the presence of common segregation distortion factors in Vigna species on this LG. One major and six minor QTLs were identified for pod length variation between yardlong bean and wild cowpea. Using flanking markers, six of the seven QTLs were confirmed in an F(2) population of JP81610 × TVnu457. The molecular linkage map developed and markers linked to pod length QTLs would be potentially useful for yardlong bean and cowpea breeding.
authors.affiliation: Program in Plant Breeding, Kasetsart University, Thailand.
authors.forename: Alisa
authors.initials: A
authors.lastname: Kongjaimun
authors.forename: Akito
authors.initials: A
authors.lastname: Kaga
authors.forename: Norihiko
authors.initials: N
authors.lastname: Tomooka
authors.forename: Prakit
authors.initials: P
authors.lastname: Somta
authors.forename: Takehiko
authors.initials: T
authors.lastname: Shimizu
authors.forename: Yujian
authors.initials: Y
authors.lastname: Shu
authors.forename: Takehisa
authors.initials: T
authors.lastname: Isemura
authors.forename: Duncan A
authors.initials: DA
authors.lastname: Vaughan
authors.forename: Peerasak
authors.initials: P
authors.lastname: Srinives
mesh_terms: D002874:Chromosome Mapping; D003433:Crosses, Genetic; D007887:Fabaceae / Q000235:genetics*; D005638:Fruit / Q000033:anatomy & histology* / Q000235:genetics; D018895:Microsatellite Repeats / Q000235:genetics*; D040641:Quantitative Trait Loci / Q000235:genetics*; D013045:Species Specificity