title: Analysis of the Physiological and Molecular Responses of Dunaliella salina to Macronutrient Deprivation.
abstract: The halotolerant chlorophyte Dunaliella salina can accumulate up to 10% of its dry weight as β-carotene in chloroplasts when subjected to adverse conditions, including nutrient deprivation. However, the mechanisms of carotenoid biosynthesis are poorly understood. Here, the physiological and molecular responses to the deprivation of nitrogen (-N), sulfur (-S), phosphorus (-P) and different combinations of those nutrients (-N-P, -N-S, -P-S and -N-P-S) were compared to gain insights into the underlying regulatory mechanisms of carotenoid biosynthesis. The results showed that both the growth and photosynthetic rates of cells were decreased during nutrient deprivation, accompanied by lipid globule accumulation and reduced chlorophyll levels. The SOD and CAT activities of the cells were altered during nutrient deprivation, but their responses were different. The total carotenoid contents of cells subjected to multiple nutrient deprivation were higher than those of cells subjected to single nutrient deprivation and non-stressed cells. The β-carotene contents of cells subjected to -N-P, -N-S and -N-P-S were higher than those of cells subjected to single nutrient deprivation. Cells subjected to sulfur deprivation accumulated more lutein than cells subjected to nitrogen and phosphorous deprivation. In contrast, no cumulative effects of nutrient deprivation on the transcription of genes in the carotenogenic pathway were observed because MEP and carotenogenic pathway genes were up-regulated during single nutrient deprivation but were downregulated during multiple nutrient deprivation. Therefore, we proposed that the carotenoid biosynthesis pathway of D. salina is regulated at both the transcriptional and posttranscriptional levels and that a complex crosstalk occurs at the physiological and molecular levels in response to the deprivation of different nutrients.
authors.affiliation: Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, P. R. China.|Tianjin Key Lab of Industrial Microbiology, Tianjin University of Science and Technology, Tianjin, P. R. China.
authors.forename: Hexin
authors.initials: H
authors.lastname: Lv
authors.affiliation: Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, P. R. China.|Tianjin Key Lab of Industrial Microbiology, Tianjin University of Science and Technology, Tianjin, P. R. China.
authors.forename: Xianggan
authors.initials: X
authors.lastname: Cui
authors.affiliation: Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, P. R. China.|Tianjin Key Lab of Industrial Microbiology, Tianjin University of Science and Technology, Tianjin, P. R. China.
authors.forename: Fazli
authors.initials: F
authors.lastname: Wahid
authors.affiliation: Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, P. R. China.|Tianjin Key Lab of Industrial Microbiology, Tianjin University of Science and Technology, Tianjin, P. R. China.
authors.forename: Feng
authors.initials: F
authors.lastname: Xia
authors.affiliation: Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, P. R. China.|Tianjin Key Lab of Industrial Microbiology, Tianjin University of Science and Technology, Tianjin, P. R. China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhong
authors.affiliation: Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, P. R. China.|Tianjin Key Lab of Industrial Microbiology, Tianjin University of Science and Technology, Tianjin, P. R. China.
authors.forename: Shiru
authors.initials: S
authors.lastname: Jia
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D053898:Biosynthetic Pathways / Q000235:genetics; D002338:Carotenoids / Q000378:metabolism; D019069:Cell Respiration; D002478:Cells, Cultured; D002734:Chlorophyll / Q000378:metabolism; D000460:Chlorophyta / Q000166:cytology / Q000235:genetics* / Q000254:growth & development / Q000502:physiology*; D005786:Gene Expression Regulation; D066292:Lipid Droplets / Q000378:metabolism; D009747:Nutritional Physiological Phenomena; D010788:Photosynthesis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D000975:Antioxidants; D012333:RNA, Messenger; D002734:Chlorophyll; D002338:Carotenoids