QTL and meta-QTLs for maximum root length on chromosome 1. The meta-QTLs on the body of the chromosome are represented by bars of different intensities of gray. The lengths of the gray segments in each QTL bar are proportional to their probability of belonging to the meta-QTL of the same intensity of gray. Distances on the map are in megabases. A color version of the figure can be found in Supplementary Figure 3.