Glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) is the first and main regulated enzyme of oxidative pentose phosphate pathway (OPPP), catalyzing the conversion of glucose-6- phosphate to 6-phospho-gluconolactone and playing important roles in the growth and development of plants. We preciously reported that the enhancement of freezing resistance of Populus suaveolens cuttings was clear related to the distinct increase in cytosolic G6PDH activity. Here, a 1697 bp cDNA fragment (PsG6PDH) was amplified by RT-PCR from cold-induced total RNA of the freezing-tolerant P. suaveolens. The sequence analysis showed that PsG6PDH coding region had 1 530 bp and encoded 510 predicted amino acid residues. Genomic Southern analysis revealed that the isoform is encoded by a few copies of the gene in the poplar genome. The cloned gene PsG6PDH was cloned into binary vector pBI121 and used to transform tobacco. PCR and Southern blotting results verified integration of this gene into the genome of tobacco. Moreove r, cold treatment experiments and membrane defense enzyme activity analysis confirmed that overexpression of the PsG6PDH gene could enhance the tolerance to cold or frigid stresses in transgenic plants.
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