Photosynthesis and photoassimilation of glucose during photomixotrophic growth of Marchantia polymorpha cells in suspension culture

Even in the presence of glucose the growth of Marchantia polymorpha L. (cell line HYH‐2F) requires light, and growth is more sensitive to 10−6M 3‐(3, 4‐dichlorophenyl)‐1, 1‐dimethylurea than to 10−4 Antimycin A. The inability of the cells to grow in the dark is due to the low level of respiration. The respiration rate under light increased to four times the dark value. The values of the compensation ratio (the photosyntehtic rate/the respiration rate) for the oxygen exchange were below 1.0 daring the growth period, although oxygen evolution was found. At the early exponential phase, oxygen evolution was 0.373 μmol (mg cell dry weight)−1 h−1 [61.7 μmol (mg chlorophyll)−1 h−1]. M. polymorpha cells are unable to grow anaerobically in the light without a supply of carbon dioxide. When 1% carbon dioxide in nitrogen is supplied, photochemically produced oxygen and energy are sufficient for sustained growth although at significantly reduced yields in both cell dry weight and chlorophyll. Photosyntehtic CO2 assimilation rate was 0.13 μmol (mg cell dry weight)−1 h−1[11.3 μmol (mg chlorophyll)−1 h−1]. At least one‐third of the carbon atoms in cellular constituents seem to be derived from atmospheric carbon dioxide, which indicates that M. polymorpha cells grow photomixotrophicaily.