Overexpression of a galactinol synthase, TsGOLS2, in Arabidopsis thaliana enhances tolerance to high salinity and osmotic stresses
Zhibin Sun1, Zenglan Wang1, Xingyun Qi1, Pinghua Li, Chunxia Wu, Hui Zhang and Yanxiu Zhao *
Key Lab of Plant Stress Research, Life Science College of Shandong Normal University, 88 Wenhua East Road, Jinan 250014, China.
1these authors contributed equally to the work.
*Corresponding author: Tel: 86-531-86180002; E-mail: zhaoyx@sdnu.edu.cn.
Abstract
Galactinol synthase (GOLS), the key enzyme in the synthesis of raffinose family oligosaccharides (RFOs), catalyzes the condensation of UDP-galactose with myo-inositol to produce galactinol as the sole donor for the synthesis of RFOs. RFOs have been implicated in mitigating effects of environmental stresses on plants. We have cloned a galactinol synthase gene from Thellungiella salsuginea. The TsGOLS2 gene (1,322 bp) contained an open reading frame of 1011 bp and encodes 337 amino acids, with high homology to AtGolS2. TsGOLS2 was up-regulated by several abiotic stresses. Using molecular biological methods, we over-expressed TsGOLS2 in A. thaliana. The contents of galactinol and raffinose were significantly increased in transgenic plants. Salt-stressed transgenic Arabidopsis plants exhibited higher germination rate, photosynthesis ability and seedling growth. Following osmotic stress by high concentration of sorbitol, transgenic plants retained high germination rates and grew well during early development. These results indicated that over-expression of TsGOLS in A. thaliana improved the tolerance to high salinity and osmotic stress of transgenic plants.
Key Words: Thellungiella salsuginea; TsGOLS2; overexpression; galactinol; raffinose; stress tolerance.
