Distribution of putative genes encoding CHYs and hypothesized xanthophylls biosynthetic pathway in algae. A] The distribution of genes encoding BCH, CrtR and CYP97 homologs across 18 algal genome sequences. The number of putative homologs or paralogs in each corresponding genome is indicated by "+" with color codes, respectively. B] Hypothesized xanthophylls biosynthetic pathway in algae. The genes encoding putative BCH-, CrtR- or CYP97-homologs identified from different algae genomes were indicated with color arrows. Lutein and α-carotene are absent in red algae and Chromalveolates according to our results. Question mark indicates enzymes involved in xanthophylls biosynthesis are unclear.