Fig. 3

LOD score profiles for bark texture (BT) QTL detected in the Populus Family 52–124. Specifically, BT QTL detected on a LG I, VIII and XIII and b LG II, VI, XII and XVIII using interval mapping (left) and the Multiple-QTL Model (MQM) with co-factor selection (right) across all experimental replicates at Oregon (OR) across 3 years and at West Virginia (WV) across 2 years. Chromosome-wide (CW) and genome-wide (GW) significance thresholds are shown with dashed lines (α = 0.05, 1000 permutations). Yellow, orange, and red solid lines represent LOD score profiles for 3-year-old replicated samples at Oregon, solid shades of green lines for 4-year-old samples, and shades of blue lines for 5-year-old samples. Dotted red and green lines represent LOD profiles for 4-year-old and 6-year-old samples at the West Virginia site. Two broken horizontal lines represent GW and CW LOD significance threshold after 1000 permutations at the p ≤ 0.05 significance level. The exact map and physical locations of QTL are shown in Additional file 4: Table S2