FIGURE 12.

HPPD1 is also regulated by dark hypoxia but γ-tocopherol content is decreased in dark hypoxic Chlamydomonas. A, abundance of CYC6, HPPD1, and HPPD2 transcripts. Independent cultures corresponding to Chlamydomonas wild-type strain CC4532 were grown in dark hypoxia. Cells were collected after reaching a density of 2–6 × 10⁶ cells/ml and analyzed for RNA abundance. Each symbol represents an independent experiment analyzed in technical triplicates. B, transcript abundance of genes encoding enzymes of the tocopherol biosynthesis pathway were determined by RNA sequencing in dark grown and dark anoxic Chlamydomonas strain CC4532 (38). The sizes of the circles are proportional to the relative abundance (RPKM) of the total transcript pool of genes encoding enzymes regulating the plastoquinone/tocopherol pathway as shown in Fig. 8. C, the tocopherol content in Chlamydomonas CC4532 that was either grown in the dark, normoxic (high) or in the dark, hypoxic (low) as indicated.