Abstract: The full-length of Glutamin synthetase (termed PsGS) gene was cloned using RACE (rapid amplification of cDNA end) technology based on GS partial sequence obtained from a random clone in SSH library of Polygonum sibiricum Laxm.. The acquired 1 273 bp sequence includes a 5′ untranslated region of 178 bp, a 3′ untranslated region of 24 bp with poly (A), and an open reading frame (ORF) encoding 356 amino acids. Based on the comparison with amino acid sequences of other plant glutamin synthetase and the phylogenetic analysis of protein evolution, this gene was divided into glutamin synthetase family. The expression analyses by RT-PCR showed that PsGS expressed in leaves, stems and rhizomes of P.sibiricum Laxm.. Under the induction of 3% NaHCO₃, the expression of PsGS was significantly influenced, which suggested that PsGS might play an important role in alkali salt stress resistance.

Key words: Polygonum sibiricum Laxm., glutamin synthetase, alkali salinity stress, gene cloning, RT-PCR