Differential parental contribution and expression dominance in each allohexaploid line. Comparison of gene expression levels among the nascent allohexaploid wheat line (Allo-AT5 or Allo-AT9), their mid-parent values (MPVs) and those of their parental species (see Figure 2 for details). Genes were ordered on X-axis by their normalized expression levels in MPVs, and the gene expression level was presented as log-ratio of normalized microarray data. Red-TTR04 or TTH01, blue-TQ27, green--Allo-AT5 or Allo-AT9 at the S4 or S5 generation, the black curve--MPVs. A1-D1, expression levels of high diploid dominance expression genes in each allohexaploid line; A2-D2, expression levels of low diploid dominance expression genes; A3-D3, expression levels of high tetraploid dominance expression genes; A4-D4, expression levels of low tetraploid dominance expression genes. The inserted graphs illustrate the expression patterns among the tetraploid, diploid and the allohexaploid, wherein statistically differential expression is denoted by different vertical levels.