title: Quantitative Trait Locus Analysis of Seed Germination and Seedling Vigor in Brassica rapa Reveals QTL Hotspots and Epistatic Interactions.
abstract: The genetic basis of seed germination and seedling vigor is largely unknown in Brassica species. We performed a study to evaluate the genetic basis of these important traits in a B. rapa doubled haploid population from a cross of a yellow-seeded oil-type yellow sarson and a black-seeded vegetable-type pak choi. We identified 26 QTL regions across all 10 linkage groups for traits related to seed weight, seed germination and seedling vigor under non-stress and salt stress conditions illustrating the polygenic nature of these traits. QTLs for multiple traits co-localized and we identified eight hotspots for quantitative trait loci (QTL) of seed weight, seed germination, and root and shoot lengths. A QTL hotspot for seed germination on A02 mapped at the B. rapa Flowering Locus C (BrFLC2). Another hotspot on A05 with salt stress specific QTLs co-located with the B. rapa Fatty acid desaturase 2 (BrFAD2) locus. Epistatic interactions were observed between QTL hotspots for seed germination on A02 and A10 and with a salt tolerance QTL on A05. These results contribute to the understanding of the genetics of seed quality and seeding vigor in B. rapa and can offer tools for Brassica breeding.
authors.affiliation: Wageningen UR Plant Breeding, Wageningen University and Research Center, Wageningen University Wageningen, Netherlands ; Centre for BioSystems Genomics Wageningen, Netherlands.
authors.forename: Ram K
authors.initials: RK
authors.lastname: Basnet
authors.affiliation: Wageningen UR Plant Breeding, Wageningen University and Research Center, Wageningen University Wageningen, Netherlands.
authors.forename: Anita
authors.initials: A
authors.lastname: Duwal
authors.affiliation: Wageningen UR Plant Breeding, Wageningen University and Research Center, Wageningen University Wageningen, Netherlands.
authors.forename: Dev N
authors.initials: DN
authors.lastname: Tiwari
authors.affiliation: Wageningen UR Plant Breeding, Wageningen University and Research Center, Wageningen University Wageningen, Netherlands ; State Key Laboratory of Crop Genetics and Germplasm Enhancement, Horticultural College, Nanjing Agricultural University Nanjing, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Xiao
authors.affiliation: Wageningen UR Plant Breeding, Wageningen University and Research Center, Wageningen University Wageningen, Netherlands ; Russian State Agrarian University, Moscow Timiryazev Agricultural Academy Moscow, Russia.
authors.forename: Sokrat
authors.initials: S
authors.lastname: Monakhos
authors.affiliation: Wageningen UR Plant Breeding, Wageningen University and Research Center, Wageningen University Wageningen, Netherlands.
authors.forename: Johan
authors.initials: J
authors.lastname: Bucher
authors.affiliation: Wageningen UR Plant Breeding, Wageningen University and Research Center, Wageningen University Wageningen, Netherlands ; Centre for BioSystems Genomics Wageningen, Netherlands.
authors.forename: Richard G F
authors.initials: RG
authors.lastname: Visser
authors.affiliation: Plant Research International Wageningen, Netherlands.
authors.forename: Steven P C
authors.initials: SP
authors.lastname: Groot
authors.affiliation: Wageningen UR Plant Breeding, Wageningen University and Research Center, Wageningen University Wageningen, Netherlands ; Centre for BioSystems Genomics Wageningen, Netherlands.
authors.forename: Guusje
authors.initials: G
authors.lastname: Bonnema
authors.affiliation: Wageningen UR Plant Breeding, Wageningen University and Research Center, Wageningen University Wageningen, Netherlands.
authors.forename: Chris
authors.initials: C
authors.lastname: Maliepaard
keywords: Brassica rapa; QTL mapping; candidate genes; salt stress; seed germination; seedling vigor