Fig. 3

Summary of codon characteristics of protein-coding genes in the S. gemmata organelle genome. A and B represent the relative synonymous codon usage (RSCU) preference distribution maps for the mitochondrial and chloroplast genomes. The horizontal coordinates represent the 21 amino acids, and the vertical coordinates are the values of RSUC. C and D indicate a projection of ENC against GC3s based on protein-coding genes in chloroplasts and mitochondria, respectively. The solid line within the figure signifies the expected trendline of gene positions given codon usage solely driven by GC3s composition. Purple dots indicate genes related to photosynthesis (C) and respiratory chain (D), red dots indicate transcription and translation-related genes, and green dots indicate other genes