title: Characterization of a glutamine synthetase gene DvGS2 from Dunaliella viridis and biochemical identification of DvGS2-transgenic Arabidopsis thaliana.
abstract: The salt-tolerant green alga Dunaliella has remarkable capability to survive in some extreme environments such as nitrogen starvation, which makes Dunaliella be a proper model for mining novel genes on nitrogen uptake or assimilation. In this study, a glutamine synthetase (GS) gene DvGS2 with amino acid identity of 72% to other homologous GS proteins, was isolated and characterized from Dunaliella viridis. Phylogenetic comparison with other GSs revealed that DvGS2 occupied an independent phylogenetic position. Expressional analysis in D. viridis cells under nitrogen starvation confirmed that DvGS2 increased its mRNA level in 12h. Subcellular localization study and functional analysis in a GS-deficient Escherichia coli mutant proved that DvGS2 was a chloroplastic and functional GS enzyme. In order to investigate the potential application of DvGS2 in higher plants, the transgenic studies of DvGS2 in Arabidopsis thaliana were carried out. Results showed that the transgenic lines expressed the DvGS2 gene and demonstrated obviously enhanced root length (29%), fresh weight (40%-48% at two concentrations of nitrate supplies), stem length (21%), leaf size (39%) and silique number (44%) in contrast with the wild-type Arabidopsis. Furthermore, the transgenic lines had higher total nitrogen content (35%-43%), total GS activity (39%-45%) and soluble protein concentration (23%-24%) than the wild type. These results indicated that the overexpression of DvGS2 in A. thaliana resulted in higher biomass and the improvement of the host's nitrogen use efficiency.
authors: Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, 99 Shangda Road, 200444 Shanghai, China.
authors: Chenguang
authors: C
authors: Zhu
authors: Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, 99 Shangda Road, 200444 Shanghai, China.
authors: Qianlan
authors: Q
authors: Fan
authors: Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, 99 Shangda Road, 200444 Shanghai, China.
authors: Wei
authors: W
authors: Wang
authors: Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, 99 Shangda Road, 200444 Shanghai, China.
authors: Chunlei
authors: C
authors: Shen
authors: Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, 99 Shangda Road, 200444 Shanghai, China.
authors: Xiangzong
authors: X
authors: Meng
authors: Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, 99 Shangda Road, 200444 Shanghai, China.
authors: Yuanping
authors: Y
authors: Tang
authors: Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, 99 Shangda Road, 200444 Shanghai, China.
authors: Bing
authors: B
authors: Mei
authors: Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, 99 Shangda Road, 200444 Shanghai, China.
authors: Zhengkai
authors: Z
authors: Xu
authors: Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, 99 Shangda Road, 200444 Shanghai, China. Electronic address: rentaosong@staff.shu.edu.cn.
authors: Rentao
authors: R
authors: Song
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D018533:Biomass; D000460:Chlorophyta / Q000235:genetics* / Q000378:metabolism; D017343:Genes, Plant / Q000235:genetics*; D005974:Glutamate-Ammonia Ligase / Q000235:genetics* / Q000378:metabolism; D058503:Mesophyll Cells / Q000378:metabolism; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000378:metabolism; D010802:Phylogeny; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D016415:Sequence Alignment; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen
keywords: Arabidopsis thaliana; CaMV; Cauliflower mosaic virus; Dunaliella viridis; EST; Expressed sequence tag; GS; Glutamine synthetase; IPTG; Isopropyl β-d-1-thiogalactopyranoside; Nitrogen use efficiency; ORF; Open reading frame; PNS; Plant nutrient solution; SD; Standard deviation; Transgenic; WT; Wild type; γ-GHA; γ-Glutamyl hydroxamate