Maximum likelihood phylogenetic tree of the ketoacyl-ACP synthase (KAS) domains and proteins of fatty acid synthases (FASs) and polyketide synthases (PKSs). The phylogenetic tree was constructed using the WAG+G+I substitution model. The multiple-alignment contained 274 gap-free columns. Approximate likelihood ratio test (aLRT) values for branch support are indicated beside branches when aLRT > 50. GenBank accession numbers and protein ids (C-169) are indicated between brackets. For C-169 proteins, the number of ESTs corresponding to the gene is shown in red. The branch length scale bar below the phylogenetic tree indicates the number of substitutions per amino acid site. The functional domain architecture of proteins is shown on the right. Protein domain names are as follows: ACP, acyl carrier protein; AT, acyl transferase; DH, hydroxyacyl-ACP dehydrase; ER, enoyl-ACP reductase; KAS, ketoacyl-ACP synthase; KR, ketoacyl-ACP reductase; MT, methyltransferase; NRPS, non-ribosomal protein synthase terminal domain; PPT, phosphopantetheinyl transferase; TE, thioesterase.