Figure 2From: Synonymous codon usage bias is correlative to intron number and shows disequilibrium among exons in plantsSC frequency based on the third nucleotide is correlated differently with intron number in algal (A) and land plant (B-E) genomes. NNA, NNT, NNC and NNG are defined as the ratio of total SCs with A, T, C and G at the third position, respectively to 59 SCs. The equivalent relationships in the other genomes investigated are shown in Additional file 4: Figure S3.Back to article page