Mobilization and Cellular Distribution of Phosphate in the Diatom Phaeodactylum tricornutum

Unicellular organisms that live in marine environments must cope with considerable fluctuations in the availability of inorganic phosphate (P(i)). Here, we investigated the extracellular P(i) concentration-dependent expression, as well as the intracellular or extracellular localization, of phosphatases and phosphate transporters of the diatom Phaeodactylum tricornutum. We identified P(i)-regulated plasma membrane-localized, ER-localized, and secreted phosphatases, in addition to plasma membrane-localized, vacuolar membrane-localized, and plastid-surrounding membrane-localized phosphate transporters that were also regulated in a P(i) concentration-dependent manner. These studies not only add further knowledge to already existing transcriptomic data, but also highlight the capacity of the diatom to distribute P(i) intracellularly and to mobilize P(i) from extracellular and intracellular resources.