Fig. 4

The evolution and RNA expression of two key enzymes in TAG synthesis. A Overview of the synthesis pathway from glycerol-3-phosphate to TAG. The gene number in the two sequenced microalgae and nine other heterokontophytes is shown in rectangle (from left to right, V. sp. H4302, V. stellata, V. sp. C74, Mo. sp. C73, Mo. sp. C141, Mi. gaditana, N. oceanica, E. siliculosus, S. japonica, P. tricornutum, T. pseudonana). The color of rectangle is reflection of relative size of the gene number in each row. Genes: GPAT, glycerol-3-phosphate acyltransferase; LPAT, 1-acyl-sn-glycerol-3-phosphate acyltransferase; PAP, phosphatidic acid phosphatase. (B) Phylogenetic tree of the DGAT gene family (Pfam motif: PF03982) from eleven heterokont genomes. Seven clades are identified based on the divergence distance and outgroup species (four non-Eustigmatophyceae species). C Phylogenetic tree of the PDAT gene family (Pfam motif: PF02450). D RNA expression of the PDAT gene family (upper panel) and the DGAT gene family (bottom panel) in V. cf. polyphem. NR, nitrogen repletion, 18 mM of initial nitrogen concentration (INC); NF, nitrogen-free, 0 mM of INC; NRC, nitrogen recovery, 15 days of NF culture, followed by transfer to 18 mM of INC medium; PF, phosphorus-free; SF, sulfur-free