Figure 3

Statistical interpretations of differential expression between parental diploids, their allopolyploid derivative, and an in silico mid-parent. The vertical axis represents relative expression level. Each taxon is labeled and color-coded with its corresponding error bar. Lanes 1 and 2 represent two separate genes with expression patterns like those in Figure 4 panels XI and II, respectively. For the first gene (lane 1), expression is higher in the D-genome than in the A-genome diploid parent. Expression in the D genome is statistically equivalent to that of the allopolyploid but not to the mid-parent (indicated by non-overlapping error bars), while expression in the allopolyploid is equivalent to both the mid-parent and the D-genome diploid. All three of the above, however, are differentially expressed relative to the A-genome diploid parent. The reverse situation is illustrated in lane 2, where expression in the D-genome parent is lower than that of the A-genome parent, rather than higher. Notice that in both lanes, expression in the allopolyploid mimics that of one parent, in this case the D genome, illustrating the general phenomenon of expression dominance of a single genome for both up- and down-regulated genes.