Transcriptomic response of marine dinoflagellate Prorocentrum cordatum to phosphorus deficiency.

Phosphorus is crucial for marine phytoplankton viability as a key biogenic element. Under phosphorus deficiency, dinoflagellates exhibit changes in their feeding regime, alterations in transporters functioning, a reduction in cell proliferation rate and, in some cases, a transition to sexual reproduction. In this study, we performed RNA-sequencing analysis to assess the transcriptomic response of the dinoflagellate Prorocentrum cordatum to phosphorus deficiency in the cultivation medium. The aim of this work was to elucidate shifts in P. cordatum life cycle under these conditions focusing on the increase in the percentage of cells with a relative nuclear DNA content of 2C and the appearance of 4C cells, which may indicate a transition to the sexual process. We identified 196 differentially expressed genes - 169 up-regulated and 27 down-regulated-in cells grown for 14 days under phosphorus-depleted conditions. Analysis revealed up-regulation of pathways for phosphate uptake and assimilation, along with activation of RNA, protein, and lipid metabolic processes. Additionally, mechanisms regulating the cell cycle and inducing meiotic division were triggered. We identified up-regulated genes encoding proteins involved in meiotic recombination, including those promoting crossover. These findings indicate that phosphorus limitation can induce shift to sexual phase in P. cordatum life cycle.