Xu, Yanan ORCID: https://orcid.org/0000-0002-1697-6070 and Harvey, Patricia ORCID: https://orcid.org/0000-0001-7193-4570 (2019) Red light Control of β-Carotene isomerisation to 9-cis β-carotene and carotenoid accumulation in Dunaliella salina. Antioxidants, 29 (5):2019050218. ISSN 2076-3921 (Online) (doi:10.3390/antiox8050148)

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Abstract

Dunaliella salina is a rich source of 9-cis β-carotene, which has been identified as important in the treatment of retinal dystrophies and other diseases. We previously showed that chlorophyll absorption of red light photons in D. salina is coupled to oxygen reduction and phytoene desaturation and increases the pool size of β-carotene [1]. Here we show for the first time that growth under red light also controls conversion of extant all-trans β-carotene to 9-cis β-carotene by β-carotene isomerases. Cells illuminated with red light from a light emitting diode (LED) during cultivation contained a higher 9-cis β-carotene content compared to cells illuminated with white or blue LED light. The 9-cis/all-trans β-carotene ratio in red light treated cultures reached >2.5:1 within 48 hours and was independent of light intensity. Illumination using red light filters that eliminated blue wavelength light also increased the 9-cis/all-trans β-carotene ratio. With norflurazon, a phytoene desaturase inhibitor which blocked downstream biosynthesis of β-carotene, extant all-trans β-carotene was converted to 9-cis β-carotene during growth with red light and the 9-cis/all-trans β-carotene ratio was ~2:1. With blue light under the same conditions, 9-cis β-carotene was likely destroyed at a greater rate than all-trans β-carotene (9-cis/all-trans ratio 0.5:1). Red light perception by the red light photoreceptor, phytochrome, may increase the pool size of anti-oxidant, specifically 9-cis β-carotene, both by upregulating phytoene synthase to increase the rate of biosynthesis of β-carotene and to reduce the rate of formation of reactive oxygen species (ROS), and by upregulating β-carotene isomerases to convert extant all-trans β-carotene to 9-cis β-carotene.

Item Type:	Article
Additional Information:	© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Uncontrolled Keywords:	9-cis β-carotene; all-trans β-carotene; Dunaliella salina; red LED; blue LED; growth; light intensity; carotenoids; isomerisation
Subjects:	Q Science > QH Natural history > QH426 Genetics
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science Faculty of Engineering & Science > Algal Biotechnology Research Group Faculty of Engineering & Science > School of Science (SCI)
Last Modified:	25 May 2020 18:06
URI:	http://gala.gre.ac.uk/id/eprint/24023

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