As one of the most important marine primary producers, diatoms are effective in absorbing phosphorus and acclimating to fluctuating levels of phosphorus in the environment. However, their response mechanisms to changes in phosphorus conditions are not well understood. Previous studies on the regulation of intracellular phosphorus homeostasis in diatoms have largely focused on the presence and similarity of land plant phosphorus-regulated genes in diatoms. Full characterization of the regulatory network of diatom phosphorus homeostasis remains challenging. Our research group was the first to discover trypsin genes in algae, and find it plays a crucial role in nitrogen-phosphorus stoichiometric balance and phosphorus homeostasis. So far, only one of the ten trypsin genes, PtTryp2, in the model diatom Phaeodactylum tricornutum has been thoroughly investigated, revealing its role in regulating N:P ratio homeostasis. My research focused on another trypsin gene, PtTryp8, which we found to be significantly up-regulated in P. tricornutum when the cells were under phosphorus deprivation. Based on this finding, we successfully constructed a PtTryp8 knockout mutant strain and a PtTryp8-reintroduced strain of P. tricornutum, and demonstrated that PtTryp8 promoted the uptake of inorganic phosphate in P. tricornutum. At the same time, we used the data of gene expression profile to further explore the regulation of trypsin gene on phosphorus homeostasis.  This research establishes the basis for understanding the role of trypsin genes in P. tricornutum, offers guidance for refining the regulatory network of phosphorus homeostasis in diatoms, and introduces a fresh perspective for monitoring the response of diatoms to changes in nutrients in the marine environment.

Trypsin, CRISPPR-Cas9, phytoplankton,,Phosphorus homeostasis