Different physiological and molecular responses of the green algae Chlorella variabilis to long-term and short-term elevated CO2

• Published in: Journal of applied phycology Vol. 32; no. 2; pp. 951 - 966
• Main Authors: Liang, Chengwei, Yang, Xiao, Wang, Lu, Fan, Xiao, Zhang, Xiaowen, Xu, Dong, Ye, Naihao
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.04.2020; Springer Nature B.V
• Subjects: Adaptation; Algae; Aquatic plants; Biomedical and Life Sciences; Carbohydrates; Carbon dioxide; Carbon fixation; Chlorella; Chlorella variabilis; Ecology; Fatty acids; Freshwater & Marine Ecology; Gene expression; Genes; Life Sciences; Lipids; Metabolism; Oxidation; Photosynthesis; Physiological responses; Physiology; Plant Physiology; Plant Sciences; Triglycerides; De novo transcriptomics; Chlorophyta; Elevated CO; Gene expression; Long term
• ISSN: 0921-8971; 1573-5176
• DOI: 10.1007/s10811-019-01943-1

Chlorella variabilis is a high-efficiency photosynthetic green plant, and its photosynthesis capacity is considerably higher than other plants. With increasing CO 2 concentration in the atmosphere C. variabilis may change the metabolism to respond to elevated CO 2. To investigate the response of C. variabilis when exposed to increased CO 2 concentrations, physiological and transcriptome analyses were carried out on C. variabilis that had been cultivated at 1000 ppm CO 2 for long (LT) and short (ST) periods of time and these were compared with samples from the control group (CT). The common responses of the ST and LT C. variabilis included increased pigment levels, and higher F v / F m and carbon fixation rates. These results indicated that current CO 2 levels could limit C. variabilis growth and photosynthesis . Transcriptome changes in the ST samples were coincident with the observed physiological responses, which suggested that carbon flow to the acetyl-CoA pool from photosynthesis enhanced the production of lipids and fatty acids. This was confirmed by the depressed β-oxidation levels, upregulation of fatty acids and triglyceride synthesis pathways, lower soluble carbohydrate contents, and lipid accumulation. However, we found no change or downregulation of genes involved in cellular metabolism in the LT samples, such as the genes participating in protein, fatty acid, and triglyceride synthesis. The results demonstrated that C. variabilis was generally sensitive to the ST condition, but hardly responded to the LT treatment and failed to evolve any specific adaptations.