Fig. 3

GC distribution in ITS2 secondary structure. A An example of the ITS2 consensus secondary structure from genus Aegilops (family Poaceae). The four stems are labelled I–IV. The characteristic bulge in stem II, and the UGGU in stem III that are common to nearly all angiosperms, are indicated in red. Degree of conservation over the entire sequences is displayed using color grades ranging from green (conservative) to red (variable). B ITS2 sequence logo of the genus Aegilops is used to visualize the base composition in different sequence-structure partitions. The overall height of the letter stack in each position indicates the sequence conservation (measured in bits), while the height of letter within the stack represents the relative frequency of the bases at that position. C The statistics of GC contents and G-C base pair frequency in ITS2 sequence-structure partitions among the 165 investigated genera