Molecular tools reveal underpinnings of phosphonate utilization by eukaryotic phytoplankton

Dissolved inorganic phosphate (DIP) is the preferred form of phosphorus (P) for marine organisms, but it can be limiting in surface waters over large swaths of the global ocean. In these DIP-deplete zones, dissolved organic phosphorus (DOP) comprises most of the total dissolved P pool as P esters (C-O-P bonds) and phosphonates (C-P bonds). Phosphonates were thought to be used solely by marine prokaryotes, though in recent studies we have shown utilization by some eukaryotic phytoplankton species. In this talk, I will discuss results from whole-cell transcriptomic analyses of three species of marine eukaryotic phytoplankton given phosphonates as the sole source of P. This work critically enhances our understanding of the metabolic capabilities of phytoplankton. This advance is especially important given the prediction that future oceans may become more stratified, further reducing vertical inputs of DIP and increasing the importance of DOP, including phosphonates, in supporting phytoplankton growth and possibly carbon export.