Diatoms are of significance in the marine ecosystem, playing a pivotal role in the sustenance of marine life and the transfer of carbon from the surface ocean to deeper waters. Although numerous studies have investigated the effects of elevated carbon dioxide (CO2) on marine diatoms across both short- and long-term adaptation scales, the molecular mechanisms governing chitin metabolism in response to ocean acidification remain poorly understood. In this study, we employed an integrated approach combining transcriptomic, metabolomic, and physiological analyses to examine the marine diatom Thalassiosira weissflogii following 40-day acclimation to high-CO2 conditions. Physiological studies have demonstrated that ocean acidification has the capacity to result in an augmentation of the C/N ratio, chitin content, maximum PSII quantum yield (Fv/Fm), and photosynthetic pigment content of T. weissflogii. Analysis of chlorophyll fluorescence dynamics further demonstrated enhanced primary photochemical efficiency of PSII in the acidified treatment group. Consistent with this, the transcriptome results also showed that the photosynthesis-related pathways were upregulated to meet the increased material and energy requirements after adaptation to elevated CO2 levels. More importantly, it was determined that acidification treatment resulted in the upregulation of chitin synthesis and the downregulation of chitin degradation in T. weissflogii, consequently leading to an augmentation in chitin content. These findings indicate that ocean acidification (high CO2, low pH) prompts T. weissflogii to prioritize the allocation of carbon resources to the synthesis of chitin. The synthesis of chitin may reinforce cell wall formation as an adaptive response to ocean acidification. Our research provides new insights into the marine acidification adaptation strategies of T. weissflogii.
Cheng M., Liu C., Li D., Wang J., Duan D. & Shao Z., in press. Carbon allocation strategy of Thalassiosira weissflogii in response to elevated pCO2. BMC Plant Biology. Article.
