With atmospheric CO₂ increasing, a large amount of CO₂ is absorbed by oceans and lakes, which changes the carbonate system and affects the survival of aquatic plants, especially microalgae. The main aim of our study was to explore the responses of Chlamydomonas reinhardtii (Chlorophyceae) to elevated CO₂ by combined transcriptome and metabolome analysis under three different scenarios: control (CK, 400 ppm), short-term elevated CO₂ (ST, 1000 ppm), and long-term elevated CO₂ (LT, 1000 ppm). The transcriptomic data showed moderate changes between ST and CK. However, metabolic analysis indicated that fatty acids (FAs) and partial amino acids (AAs) were increased under ST. There was a global downregulation of genes involved in photosynthesis, glycolysis, lipid metabolism, and nitrogen metabolism but increase in the TCA cycle and β-oxidation under LT. Integrated transcriptome and metabolome analyses demonstrated that the nutritional constituents (FAs, AAs) under LT were poor compared with CK, and most genes and metabolites involved in C and N metabolism were significantly downregulated. However, the growth and photosynthesis of cells under LT increased significantly. Thus, C. reinhardtii could form a specific adaptive evolution to elevated CO₂, affecting future biogeochemical cycles.

随着大气CO _{2 的}增加，大量的CO ₂被海洋和湖泊吸收，改变了碳酸盐体系，影响了水生植物特别是微藻的生存。我们研究的主要目的是通过结合转录组和代谢组分析在三种不同情况下探索莱茵衣藻（绿藻科）对升高的 CO ₂的反应：对照（CK，400 ppm）、短期升高的 CO ₂（ST，1000 ppm) 和长期升高的 CO ₂（LT，1000 ppm）。转录组数据显示 ST 和 CK 之间有适度的变化。然而，代谢分析表明脂肪酸 (FAs) 和部分氨基酸 (AAs) 在 ST 下增加。涉及光合作用、糖酵解、脂质代谢和氮代谢的基因整体下调，但在 LT 下 TCA 循环和 β-氧化增加。综合转录组和代谢组分析表明，与 CK 相比，LT 下的营养成分（FAs、AAs）较差，并且大多数参与 C 和 N 代谢的基因和代谢物显着下调。然而，LT下细胞的生长和光合作用显着增加。因此，C. reinhardtii可以对升高的 CO ₂形成特定的适应性进化，影响未来的生物地球化学循环。