QTL mapping of root and aboveground biomass in the Brassica C genome using a B. napus population carrying genome content introgressed from B. oleracea

Abstract

Root and aboveground biomass are important traits for resource acquisition and play an important role in the plant’s competitive ability and contribute to seed yield. A linkage map of the C genome of Brassica napus was constructed using a doubled haploid population, derived from cross between a B. napus line RIL144 carrying genome content introgressed from B. oleracea and a B. napus cultivar Hi-Q, and using SNP and SSR markers. The mapping population was evaluated for these two traits in a growth chamber set at 18/8 °C and 16 h photoperiod. Variation for both traits including transgressive segregation for root biomass was found. Ten QTL on chromosomes C1, C2, C6, C7 and C9 affecting root biomass and seven QTL on C1, C2, C4 and C8 affecting aboveground biomass were detected; among these, QTL allele of C2 and C6 of RIL-144 increased root biomass. Two additive × additive epistatic interactions were detected for aboveground biomass; the epistatic effects were 2–3 folds greater than the main effect of the QTL implying that gene interaction plays as an important role for this trait. BLASTn search of the C1, C2, C6 and C9 QTL regions showed homoeology with Arabidopsis thaliana chromosome At1, C9 QTL showed homoeology with At4 and At5, and C7 QTL showed homoeology with At2; these A. thaliana chromosome regions found to carry genes regulating root characteristics. Thus, the molecular markers identified and the knowledge of the genomic regions gained from this research can be used to improve the root and aboveground biomass traits of B. napus.