Construction Of A Genetic Linkage Map And QTLs Analysis Of Main Quality Traits In Radish (Raphanus Sativus L.)

Radish(Raphanus sativus L.) is an important vegetable originated from China and has abundant germplasm.Quality traits are the important fields of breeding programs as the improvement of living standard. Construction of the molecular linkage map is the base for location of significant horticulture character. Mapping of radish main quality traits could elucidate the genetic base of quality traits and promote marker-assisted selection and breeding programs of high-quality. The study on genetic linkage map of radish was poor. QTLs (Quantitative Trait Loci) analysis of main quality traits in radish has not been reported. In this study, a genetic linkage map of radish was constructed with molecular markers and processed QTLs analysis of main quality traits in radish. The result could provide theoretical basis for parsed the genetic base of quality traits and promote breeding programs of high-quality.In this study, a genetic linkage map of radish was constructed with F2 population consisting of 169 individuals from a cross of inbred line NAU-XWH (R. sativus L.) (High nutrient quality)×inbred line NAU-LHZ (R.sativus L. var raphanistroid) (low nutritient quality) based on random amplified polymorphic DNA (RAPD) and Sequence related amplified polymorphism (SRAP) markers. A total of 139 marker loci which were assayed in the population,and the map consisted of 11 linkage groups which included 80 loci (30 RAPD and 50 SRAP),and spanned 739.5 cM of the Radish genome with an average distance of 9.2 cM between two markers.Fifty-nine markers were still unlinked, accounting for 42.4% of total markers. There were several big gaps and some little linkage groups in the map due to that RAPD markers are random distributed on the chromosome and the cross-over value between different sections of chromosome are heterogenous.Based on the genetic linkage map and WinQTLCart V2.5, the QTLs location analysis of crude fiber content, dry matter content, nitrate content, total soluble sugar content, protein content and Vc content traits of radish was generated. Seven putative QTLs for crude fiber content were detected and located on LG01, LG03, LG05 and LG07,respectively, which explained 10% of the total phenotypic variance; One putative QTLs for dry matter content trait were detected and located on LG06, which explained 5.3% of the total phenotypic variance; seven putative QTLs for nitrate content were detected and located on LG01,which explained 21.8% of the total phenotypic variance; two putative QTLs for total soluble sugar content were detected and located on LG01, which explained 12.5% of the total phenotypic variance; eleven putative QTLs for protein content were detected and located on LG01, LG03, LG05, LG6 and LG07,respectively, which explained 89.9% of the total phenotypic variance; none putative QTLs for Vc content were detected in this genetic linkage map.