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A High Density Linkage Map Facilitates QTL Mapping of Flowering Time in Brassica rapa

Liu, Jing, Liu, Bo, Cheng, Feng, Liang, Jianli, Wang, Xiaowu, Wu, Jian
Horticultural plant journal 2016 v.2 no.4 pp. 217-223
Brassica rapa subsp. pekinensis, Chinese cabbage, chromosome mapping, doubled haploids, flowering date, genome, horticultural crops, life history, parents, quantitative trait loci, single nucleotide polymorphism
Flowering is a major developmental transition in the life-history of plants. Flowering time is under complex genetic control. In this study, 172 doubled haploid (DH) lines derived from a cross between two Chinese cabbage (Brassica rapa ssp. pekinensis) DH lines, Y177 and Y195, were used for a high density linkage map construction and quantitative trait locus (QTL) mapping for flowering time in B. rapa. Parents and DH lines were resequenced at depth of 5× and 0.5× coverage, respectively. In total, 22 747 SNPs were called from the resequencing data and combined into 1 708 bins to construct the genetic linkage map. The map length was 958.6 cM, containing 887 bins and the average interval between bin-markers was 1.08 cM. A total of six QTLs controlling flowering time were detected under four different conditions. Potential candidate flowering homologues located near QTLs were identified with the aid of B. rapa genome annotation.