Mechanisms for carbon fixation via photosynthesis in the diatom Phaeodactylum tricornutum Bohlin were studied recently but there remains a long-standing debate concerning the occurrence of C4 photosynthesis in this species. A thorough investigation of carbon metabolism and the evidence for C4 photosynthesis based on organelle partitioning was needed.Methods and Results:
In this study, we identified the flux ratios between C3 and C4 compounds in P. tricornutum using 13C-labelling metabolic flux ratio analysis, and stained cells with various cell-permeant fluorescent probes to investigate the likely organelle partitioning required for single-cell C4 photosynthesis. Metabolic flux ratio analysis indicated the C3/C4 exchange ratios were high. Cell staining indicated organelle partitioning required for single-cell C4 photosynthesis might exist in P. tricornutum.Conclusion:
The results of 13C-labelling metabolic flux ratio analysis and cell staining suggest single-cell C4 photosynthesis exists in P. tricornutum.Significance and Impact of the Study:
This study provides insights into photosynthesis patterns of P. tricornutum and the evidence for C4 photosynthesis based on 13C-labelling metabolic flux ratio analysis and organelle partitioning.