AUTHOR=Xi Yimei , Kong Fantao , Chi Zhanyou 

TITLE=ROS Induce β-Carotene Biosynthesis Caused by Changes of Photosynthesis Efficiency and Energy Metabolism in Dunaliella salina Under Stress Conditions

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2020.613768

DOI=10.3389/fbioe.2020.613768

ISSN=2296-4185

ABSTRACT=<p>The unicellular alga <italic>Dunaliella salina</italic> is regarded as a promising cell factory for the commercial production of β-carotene due to its high yield of carotenoids. However, the underlying mechanism of β-carotene accumulation is still unclear. In this study, the regulatory mechanism of β-carotene accumulation in <italic>D. salina</italic> under stress conditions was investigated. Our results indicated that there is a significant positive correlation between the cellular ROS level and β-carotene content, and the maximum quantum efficiency (<italic>F</italic><sub><italic>v</italic></sub><italic>/F</italic><sub><italic>m</italic></sub>) of PSII is negatively correlated with β-carotene content under stress conditions. The increase of ROS was found to be coupled with the inhibition of <italic>F</italic><sub><italic>v</italic></sub><italic>/F</italic><sub><italic>m</italic></sub> of PSII in <italic>D. salina</italic> under stress conditions. Furthermore, transcriptomic analysis of the cells cultivated with H<sub>2</sub>O<sub>2</sub> supplementation showed that the major differentially expressed genes involved in β-carotene metabolism were upregulated, whereas the genes involved in photosynthesis were downregulated. These results indicated that ROS induce β-carotene accumulation in <italic>D. salina</italic> through fine-tuning genes which were involved in photosynthesis and β-carotene biosynthesis. Our study provided a better understanding of the regulatory mechanism involved in β-carotene accumulation in <italic>D. salina</italic>, which might be useful for overaccumulation of carotenoids and other valuable compounds in other microalgae.</p>