Remodeling of Chlamydomonas Metabolism Using Synthetic Inducers Results in Lipid Storage during Growth

Authors

Nishikant Wase, University of Nebraska-LincolnFollow
Boqiang Tu, University of Nebraska-LincolnFollow
Girish Kumar Rasineni, University of Nebraska - Lincoln
Ronald Cerny, University of Nebraska - LincolnFollow
Ryan Grove, University of Nebraska - Lincoln
Jiri Adamec, University of Nebraska-LincolnFollow
Paul N. Black, University of Nebraska-LincolnFollow
Concetta DiRusso, University of Nebraska - LincolnFollow

ORCID IDs

0-0002-8955-3300 Nishikant Wase

0000-0002-3999-1986 Boqiang Tu,

0000-0002-7821-8021 Girish Kumar Rasineni

0000-0002-3765-2470 Ronald Cerny,

0000-0002-1309-3360 Ryan Grove

0000-0003-4899-4406 Jiri Adamec

0000-0002-6272-6881 Paul N. Black

0000-0001-7388-9152 Concetta DiRusso

Document Type

Article

Date of this Version

11-2019

Citation

Plant Physiology, November 2019, Vol. 181, pp. 1029–1049

Comments

PMCID: PMC6836844

(c) 2019 American Society of Plant Biologists

Abstract

Microalgae accumulate lipids during stress such as that of nutrient deprivation, concomitant with cessation of growth and depletion of chloroplasts. By contrast, certain small chemical compounds selected by high-throughput screening in Chlamydomonas reinhardtii can induce lipid accumulation during growth, maintaining biomass. Comprehensive pathway analyses using proteomics, transcriptomics, and metabolomics data were acquired from Chlamydomonas cells grown in the presence of one of two structurally distinct lipid activators. WD10784 stimulates both starch and lipid accumulation, whereas WD30030-treated cells accumulate only lipids. The differences in starch accumulation are largely due to differential effects of the two compounds on substrate levels that feed into starch synthesis and on genes encoding starch metabolic enzymes. The compounds had differential effects on photosynthesis, respiration, and oxidative stress pathways. Cells treated with WD10784 showed slowed growth over time and reduced abundance of photosynthetic proteins, decreased respiration, and increased oxidative stress proteins, glutathione, and reactive oxygen species specific to this compound. Both compounds maintained central carbon and nitrogen metabolism, including the tricarboxylic acid cycle, glycolysis, respiration, and the Calvin–Benson–Bassham cycle. There were few changes in proteins and transcripts related to fatty acid biosynthesis, whereas proteins and transcripts for triglyceride production were elevated, suggesting that lipid synthesis is largely driven by substrate availability. This study reports that the compound WD30030 and, to a lesser extent WD10784, increases lipid and lipid droplet synthesis and storage without restricting growth or biomass accumulation by mechanisms that are substantially different from nutrient deprivation.