Transcriptional responses of the marine diatom Chaetoceros tenuissimus to phosphate deficiency

The planktonic diatom Chaetoceros tenuissimus sometimes forms blooms in coastal surface waters where dissolved inorganic phosphorus (P) is typically deficient. To understand the molecular mechanisms for survival under Pdeficient conditions, we compared whole transcripts and metabolites with P-sufficient conditions using stationary growth cells. Under P-deficient conditions, cell numbers and photosynthetic activities decreased as cells entered the stationary growth phase, with downregulation of transcripts related to the Calvin cycle and glycolysis/gluconeogenesis. Therefore, metabolites varied across nutritional conditions. Alkaline phosphatase, phosphodiesterase, phytase, phosphate transporter, and transcription factor genes were drastically upregulated under dissolved inorganic P deficiency. Genes related to phospholipid degradation and nonphospholipid synthesis were also upregulated. These results indicate that C. tenuissimus rearranges its membrane composition from phospholipids to nonphospholipids to conserve phosphate. To endure in P-deficient conditions, C. tenuissimus modifies its gene responses, suggesting a potential survival strategy in nature.

Automated summary

The planktonic diatom Chaetoceros tenuissimus forms blooms in coastal surface waters with deficient dissolved inorganic phosphorus (P). In this study, the researchers compared whole transcripts and metabolites of Chaetoceros tenuissimus under P-deficient and P-sufficient conditions. They found that under P-deficient conditions, cell numbers and photosynthetic activities decreased, and genes related to the Calvin cycle and glycolysis/gluconeogenesis were downregulated. Genes related to phospholipid degradation and nonphospholipid synthesis were upregulated, suggesting a potential survival strategy for C. tenuissimus in P-deficient conditions.