Nutrient Limitation is the Main Regulatory Factor for Carotenoid Accumulation and for Psy and Pds Steady State Transcript Levels in Dunaliella salina (Chlorophyta) Exposed to High Light and Salt Stress

• Published in: Marine biotechnology (New York, N.Y.) N.Y.), 2008-09, Vol.10 (5), p.602-611, Article 602
• Main Authors: Coesel, Sacha Nicole, Baumgartner, Alexandra Cordeiro, Teles, Licia Marlene, Ramos, Ana Alexandra, Henriques, Nuno Miguel, Cancela, Leonor, Varela, João Carlos Serafim
• Format: Article
• Language: English
• Subjects: Abiotic stress; Accumulation; Adaptation; Alkyl and Aryl Transferases - genetics; Biomedical and Life Sciences; Biosynthesis; Carotene; Carotenoid biosynthesis; Carotenoids; Carotenoids - metabolism; Cell division; Cells; Chlorophyll; Chlorophyta - drug effects; Chlorophyta - genetics; Chlorophyta - metabolism; Chlorophyta - radiation effects; Chloroplasts; Culture Media - chemistry; Desaturase; Dunaliella salina; Engineering; Enzymes; Food; Freshwater & Marine Ecology; Gene Expression Regulation - drug effects; Geranylgeranyl-Diphosphate Geranylgeranyltransferase; Growth conditions; Harsh environments; Life Sciences; Light; Marine biology; Microbiology; Mineral nutrients; mRNA; nitrates; Nitrates - analysis; Nutrient availability; Nutrients; Organisms; Original Article; Oxidoreductases - genetics; Phytoene synthase; Polymerase chain reaction; Regulation; RNA, Messenger - metabolism; Salinity; Salt; Salts; Sodium chloride; Sodium Chloride - pharmacology; Steady state; Stress; Studies; Time Factors; Zoology; β-Carotene
• ISSN: 1436-2228; 1436-2236
• DOI: 10.1007/s10126-008-9100-2

Dunaliella salina (Dunal) Teodoresco (1905) is a green unicellular alga able to withstand severe salt, light, and nutrient stress, adaptations necessary to grow in harsh environments such as salt ponds. In response to such growth conditions, this microalga accumulates high amounts of β-carotene in its single chloroplast. In this study, we show that carotenoid accumulation is consistently inhibited in cells grown in nutrient-supplemented media and exposed either to high-light or medium-low-light conditions. Likewise, carotenogenesis in cells shifted to higher salinity (up to 27% NaCl) under medium-low-light conditions is inhibited by the presence of nutrients. The steady-state levels of transcripts encoding phytoene synthase and phytoene desaturase increased substantially in D. salina cells shifted to high light or high salt under nutrient-limiting conditions, whereas the presence of nutrients inhibited this response. The regulatory effect of nutrient availability on the accumulation of carotenoids and messenger RNA levels of the first two enzymes committed to carotenoid biosynthesis is discussed.