Cloning, Characterization And Expression Of A Galactinol Synthase Gene From Cold Stressed Pepper (Capsicum Annuum Linn.)

When plants are exposed to cold or desiccation stress, the raffinose family oligosaccharides (RFOs) could accumulate as osmotically regulated substance to maintain osmotic pressure and enhance the ability of stress tolerance. Galactinol synthase (GS) catalyzes the first committed step in the biosynthesis of RFOs, plays a key regulatory role in the accumulation of raffinose, stachyose, and verbascose. Thus, investigating the expression pattern of GS under low temperature may offer important clue to study the plant response to cold stress.Full length cDNA sequence of a galactinol synthase family gene (GS) (Genbank locus: EF566470) was cloned from cold-stressed pepper (Capsicum annuum Linn.'Suchanghong') leaves using RT-PCR and rapid amplification of cDNA ends (RACE). The gene consists of 1444 bp encoding a protein of 336 amino acids. Phylogenetic analysis revealed that this gene is high homologous to reported GS genes of other plants. Southern blot analysis indicated that there may be other GS gene copies in the pepper genome. RT-PCR analysis showed that the mRNAs of this gene was induced in pepper leaves after 4℃or 10℃cold-treatment for 6 h, but not accumulated in cold -stressed stems and roots, no mRNA of this gene can be detected in pepper tissues under normal temperature. Northern blot analysis showed that , GS gene expressed only at cold acclimation after 6h , and with the longer duration at cold condition and the depress of the temperature ,the higher it expressed.The result of this study confirmed that GS gene can be induced by low temperature in pepper, and its expression amount is related to the temperature and its duration. Thus, the conclusion establishes favorable basic to do further research work about the physiological function of GS and RFOs in plants in the process of resisting adversity.The result of this study confirmed that GS gene can be induced by low temperature in pepper, and its expression is related to the temperature and the stress duration. The conclusion is beneficial to further research the physiological function of GS and RFOs in plant response to abiotic stress.