Data of head traits in the parents and the RIL population.

<p>Data of head traits in the parents and the RIL population.</p

Leaf traits of heading Chinese cabbage and non-heading Chinese cabbage and their recombination lines.

<p>Leaf traits of heading Chinese cabbage and non-heading Chinese cabbage and their recombination lines.</p

The correlation coefficients between different traits and years.

**<p>Significant at P≤0.0001.</p

Frequency distributions of 6 head traits in the RIL lines and their parental lines.

<p>The vertical axis of each figure represents the number of RIL lines. Arrows show the mean values for the parental lines Bre and Wut.</p

Linkage relationship between the QTLs for head traits.

<p>The names of QTLs are described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0076059#pone-0076059-t003" target="_blank">Table 3</a>. The black and grey arrow heads indicate the locations of QTLs in 2011 and 2012, respectively. The locations of the QTLs for qTr and qLW in the two years are the same and indicated by white arrow heads.</p

Recombination map and linkage map.

<p>(A) Recobination map of 150 RILs; (B) Pairwise recombination fractions and LOD scores; (C) Genetic linkage map after filtering markers that recombination rates higher than 20%.</p