2.10 Relative expression changes of homoeologous genes under UV-B stress
To detect the relative expression changes of homoeologous genes, the ratio of of At-homoeolog to Dt-homoeolog (At/Dt) at expression level was calculated for each pair of genes. The ratio with no statistical significance (P ≥ 0.05) was recorded as 1. Then, relative expression status of each homoeologous pair was classified into unbiased (At/Dt=1) and biased (At/Dt≠1) expression. Unbiased expression refers to the absence of expression bias between At- and Dt- homoeologs under CK and UV-B stress conditions (no bias) or only under UV-B stress (lost bias); biased expression refers to the existence of expression bias between At- and Dt- homoeologs under UV-B stress. For the latter case, which can further be classified into four situations: (1) no expression bias occurred under CK condition, but the expression of At-homoeolog dominated under UV-B stress (Get At bias); (2) no expression bias occurred under CK condition, but the expression of Dt-homoeolog dominated under UV-B stress (get Dt bias); (3) significant expression bias occurred between At- and Dt- homoeologs under CK condition, but the expression of At-homoeolog dominated under UV-B stress (At bias); (4) significant expression bias occurred between At- and Dt- homoeologs under CK condition, but the expression of Dt-homoeolog dominated under UV-B stress (Dt bias).
Results