Fig. 2

Chloroplast genome structure and gene expression across tracheophytes. These 658 chloroplast genomes were downloaded from NCBI Organelle Resources. The X-axis indicates the taxonomy of the chloroplast genome species following the Angiosperm Phylogeny Group III system and NCBI taxonomy. The bar width represents 100 species. The Y-axis shows the chloroplast genes, which were classified by different chloroplast regions. Gray boxes indicate absence of genes. Red boxes indicate stop codons in genes. Blue boxes indicate unknown nucleotides (N) in genes. IR inverted repeat, LSC large single-copy region, SSC small single-copy region