Multi-omics analysis of the molecular adaptation of bloom-forming diatom Chaetoceros curvisetus to different phosphorus regimes.

Imbalanced nitrogen and phosphorus loadings and disrupted phosphorus cycling have caused phosphorus fluctuations to dominate phytoplankton growth restriction in China's coastal waters in recent years. Chaetoceros curvisetus, a dominant bloom-forming diatom in the East China Sea and adjacent waters, exhibits strong sensitivity to phosphorus variability. Multi-omics screening under low phosphorus treatment yielded 151 differentially expressed genes (DEGs), 397 differentially expressed proteins (DEPs) and 191 differentially accumulated metabolites (DAMs). Major molecular adaptations featured reduced abundances of inorganic phosphate transmembrane transporters (proteome), together with enhanced alkaline phosphatase transcripts (transcriptome), a metabolic shift predicted to boost environmental phosphorus scavenging. Under medium phosphorus treatment, 93 DEGs, 340 DEPs and 314 DAMs were recovered; sodium-dependent phosphate transporter transcripts were strongly upregulated, consistent with improved phosphate scavenging capacity. Enrichment analysis identified major disruptions to photosynthesis and glycerophospholipid metabolism pathways. Under different phosphorus regimes, C. curvisetus exhibits concurrent changes in photosynthesis and the tricarboxylic acid cycle, together with nutrient transport and lipid metabolism, reflecting modified core cellular functions. Overall, this study unravels the multi-omics regulatory mechanisms of C. curvisetus responding to fluctuating phosphorus availability, and provides a fundamental framework for exploring how this diatom copes with environmental phosphorus shifts.