Molecular cloning and characterisation of cytoplasmic glutamine synthetase gene BcGS1 from non-heading Chinese cabbage.
BACKGROUND
Glutamine synthetase (GS; EC 6.3.1.2) is a key enzyme of nitrogen (N) assimilation, catalysing the synthesis of glutamine from ammonium and glutamate. Plants have two types of GS isoenzyme that are localised in different compartments: one in the cytosol (GS1) and the other in the chloroplast (GS2). GS1 is the major form of GS in plant roots and directly converts ammonium taken up by plant roots to glutamine.


RESULTS
The GS1 gene cDNA of non-heading Chinese cabbage (Brassica campestrisssp. chinensis Makino) cultivar 'Suzhouqing' was isolated by RT-PCR (real-time polymerase chain reaction) and (5'/3')-RACE (rapid amplification of cDNA ends) techniques. It was classified as GS1 by sequence alignment and motif search and named B. campestris ssp. chinensis Makino GS1 (BcGS1). Subcellular localisation analysis showed that BcGS1 was distributed in the cytoplasm of cells. BcGS1 was expressed in all parts, but mainly in the roots, which was verified by northern blotting analysis. Additionally, its expression was influenced by the N source concentration.


CONCLUSIONS
These results suggest that BcGS1 is a novel member of the GS family in plants. BcGS1 was significantly related to N assimilation in non-heading Chinese cabbage, demonstrating that this gene plays an important role in plant growth and development.
Sun
Feifei
F
State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
Yang
Xuedong
X
Li
Ying
Y
Hou
Xilin
X
D016960:Agrobacterium tumefaciens / Q000235:genetics; D000595:Amino Acid Sequence; D001937:Brassica / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D003600:Cytosol / Q000201:enzymology; D018076:DNA, Complementary; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005974:Glutamate-Ammonia Ligase / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000008:administration & dosage; D021141:Nucleic Acid Amplification Techniques; D019697:Onions / Q000166:cytology / Q000235:genetics; D009994:Osmolar Concentration; D010802:Phylogeny; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013997:Time Factors
D018076:DNA, Complementary; D007527:Isoenzymes; D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen