Mapping QTLs for root morphological traits inBrassica rapa L. based on AFLP and RAPD markers
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Root growth and thickening plays a key role in the final productivity and even the quality of storage roots in root crops. This study was conducted to identify and map quantitative trait loci (QTLs) affecting root morphological traits inBrassica rapa by using molecular markers. An F2 population was developed from a cross between Chinese cabbage (Brassica rapa ssp.chinensis) and turnip (B. rapa ssp.rapifera), which differed greatly in root characters. A genetic map covering 1837.1 cM, with 192 marker loci and 11 linkage groups, was constructed by using this F2 population. The F3 families derived from F2 plants were grown in the field and evaluated for taproot traits (thickness, length, and weight). QTL analysis via simple interval mapping detected 18 QTLs for the 3 root traits, including 7 QTLs for taproot thickness, 5 QTLs for taproot length, and 6 QTLs for taproot weight. Individually, the QTLs accounted for 8.4–27.4% of the phenotypic variation. The 2 major QTLs,qTRT4b for taproot thickness andqTRW4 for taproot weight, explained 27.4% and 24.8% of the total phenotypic variance, respectively. The QTLs for root traits, firstly detected inBrassica crops, may provide a basis for marker-assisted selection to improve productivity in root-crop breeding.
KeywordsBrassica rapa L. turnip Chinese cabbage molecular markers taproot characters quantitative trait loci
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- Ajisaka H, Kuginuki Y, Yui S, Enomoto S, Hirai M, 2001. Identification and mapping of a quantitative trait locus controlling extreme late bolting in Chinese cabbage (Brassica rapa L. ssppekinensis syn.campestris L.) using bulked segregant analysis: a QTL controlling extreme late bolting in Chinese cabbage. Euphytica 118: 75–81.CrossRefGoogle Scholar
- Chen H, 2001. Atlas of the traditional vegetables in China. Zhejiang Science and Technology Publishing House, China: 123–124.Google Scholar
- Kosambi DD, 1944. The estimation of map distances from recombination values. Ann Eugen 12: 172–175.Google Scholar
- Lincoln SE, Daly MJ, Lander ES, 1992. Construction of genetic maps with MAPMAKER/EXP 3.0. Whitehead Inst Tech Rep Whitehead Inst., Cambridge.Google Scholar
- Lu G, Zhuang XY, 2004. Changes of sink activity and soluble protein during tap-root thickening. J Zhejiang University 30: 39–43 (in Chinese with English Abstract).Google Scholar
- SAS Institute, 1989. SAS/STAT user’s guide, version 6, 4th edn. SAS Institute, Cary, N.C.Google Scholar
- Song KM, Slocum MK, Osborn TC, 1995. Molecular marker analysis of genes encoding morphological variation inBrassica rapa (syn.campestris). Theor Appl Genet 90: 1–10.Google Scholar
- Zobel R, 1986. Rhizogenetics (root genetics) of vegetable crops. HortScience 21: 956–959.Google Scholar