Abstract
Phosphorus (P) limits primary production in regions of the surface ocean, and many plankton species exhibit specific physiological responses to P-deficiency. The metabolic response of Micromonas pusilla, an ecologically relevant marine photoautotroph, to P-deficiency was investigated using environmental metabolomics and comparative genomics. The concentrations of some intracellular metabolites were elevated in the P-deficient cells (e.g., xanthine) and genes involved in the associated metabolic pathways shared a significant motif in the non-coding regions of the gene. The presence of the conserved motif suggests that these genes may be co-regulated, and the motif may constitute a regulatory element for binding a transcription factor (i.e., Psr1). A putative phosphate starvation response gene (psr1-like) was identified in M. pusilla with homology to well characterized psr1/phr1 genes in freshwater algae and plants. This gene appears to be present and expressed in other marine algal taxa, such as the abundant haptophyte Emiliania huxleyi, in chronically phosphorus-limited field sites. Results from the present study have implications for our understanding of taxon-specific roles in mediating P cycling in the ocean.
Footnotes
Competing interest statement: The authors declare that they have no conflict of interest