Fig. 1

Tocochromanol biosynthesis pathway. The two precursor pathways and the carotenoid pathway are represented as black boxes. The six quantified tocochromanols and chlorophyll a are indicated in black nonitalicized text. The names of key a priori genes are bolded and italicized at the pathway step(s) catalyzed by their encoded enzymes, with the POR genes in red text. The key tocopherol precursor phytol is bolded in red. Compound abbreviations: DMGGBQ, 2,3-dimethyl-5-geranylgeranyl-1,4-benzoquinol; DMPBQ, 2,3-dimethyl-6-phytyl-1,4-benzoquinol; GGDP, geranylgeranyl diphosphate; GG-Chlorophyll, geranylgeranyl-chlorophyll a; HGA, homogentisic acid; HPP, p-hydroxyphenylpyruvate; MGGBQ, 2-methyl-6-geranylgeranyl-1,4-benzoquinol; MPBQ, 2-methyl-6-phytyl-1,4-benzoquinol; Phytyl-DP, phytyl diphosphate; Phytyl-P, phytyl monophosphate. Gene abbreviations: chlorophyll synthase (CHS); chlorophyll dephytylase1 (CLD1); farnesol kinase (FOLK); geranylgeranyl reductase (GGR); homogentisate geranylgeranyl transferase (HGGT); light harvesting protein-like 3 (LIL3); protochlorophyllide reductase (POR1, POR2, and POR3); tocopherol cyclase (VTE1); homogentisate phytyltransferase (VTE2); MPBQ/MGGBQ methyltransferase (VTE3); γ-tocopherol methyltransferase (VTE4); phytol kinase (VTE5); phytol phosphate kinase (VTE6); α-/β-hydrolase (VTE7). Figure updated from [55]