Comparative Transcriptomic Analysis Reveals Novel Insights into the Adaptive Response of Skeletonema costatum to Changing Ambient Phosphorus

Abstract

Phosphorus (P) is a limiting macronutrient for diatom growth and productivity in the ocean. Much effort has been devoted to the physiological response of marine diatoms to ambient P change, however, the whole-genome molecular mechanisms are poorly understood. Here, we utilized RNA-Seq to compare the global gene expression patterns of a marine diatom Skeletonema costatum grown in inorganic P-replete, P-deficient, and inorganic- and organic-P resupplied conditions. In total 34,942 unique genes were assembled and 20.8% of them altered significantly in abundance under different P conditions. Genes encoding key enzymes/proteins involved in P utilization, nucleotide metabolism, photosynthesis, glycolysis, and cell cycle regulation were significantly up-regulated in P-deficient cells. Genes participating in circadian rhythm regulation, such as circadian clock associated 1, were also up-regulated in P-deficient cells. The response of S. costatum to ambient P deficiency shows several similarities to the well-described responses of other marine diatom species, but also has its unique features. S. costatum has evolved the ability to re-program its circadian clock and intracellular biological processes in response to ambient P deficiency. This study provides new insights into the adaptive mechanisms to ambient P deficiency in marine diatoms.

Metatranscriptome analysis reveals environmental and diel regulation of a Heterosigma akashiwo (raphidophyceae) bloom

“…Consistent with this, in the sequenced metatranscriptome, several sets of H. akashiwo genes associated with P metabolism were up‐regulated in the bloom samples. First, we observed up‐regulated expression of inorganic phosphate transporter, pho4 and spts , genes that have been shown to facilitate efficient uptake of P under P‐limited conditions (Dyhrman et al ., ; Wurch et al ., ; Zhang et al ., ; Haley et al ., ). Second, utilization of DOP via AP to sustain growth has been documented in many phytoplankton species (Dyhrman et al ., ; Lin et al ., ).…”

The effects of phosphorus limitation on carbon metabolism in diatoms

“…P. tricornutum and T. pseudonana were chosen as the localization of the different isozymes are well predicted for these species [37,38]. The treatment was also similar in the three compared experiments ( P. tricornutum and S. costatum , 96 h P depletion [28,31]; T. pseudonana , 100 h P depletion [26]). Expression data were only available for a few carbon metabolism pathways for S. costatum .…”

Functional Differences in the Blooming Phytoplankton Heterosigma akashiwo and Prorocentrum donghaiense Revealed by Comparative Metaproteomics

“…Polyphosphate serves as both a major cellular phosphate reservoir and an energy storage pool that can be used as a source of ATP (65). Some phytoplankton species can acquire Pi to synthesize polyphosphate under Pi-sufficient conditions and degrade polyphosphate to release Pi through upregulation of VTC4 under Pi-deficient conditions (66,67). These results indicated that H. akashiwo initiates external phosphate transport and internal storage systems to adapt to low-Pi environments, thus supporting its bloom prior to that of P. donghaiense.…”

“…Protein phosphatase, acid phosphatase, and 3=(2=),5=-bisphosphate nucleotidase hydrolyze phosphoric esters, while phospholipase and phosphatidylinositol phospholipase C hydrolyze structural phospholipids to release phosphate (69)(70)(71). These enzymes and their homologs involved in DOP reutilization are found to be highly expressed under P-deficient conditions (66)(67)(68). The multiple but varied DOP utilization strategies enable H. akashiwo and P. donghaiense to adapt to low-Pi concentrations during their blooming periods.…”