Gene Cloning, Structure Analysis And Function Identification Of Glucose-6-phosphate Dehydrogenase From Populus Suaveolens

Populus suaveolens is a species in section Tacamahaca and mainly distributed in the area of North America and Asia. In China, it is mainly distributed in the northern part of Daxing'an Mountain and the area of Mo'he. P. suaveolens, freezing-resistant arbor plants, can survive under a temperature of approximately -43.5 oC, and therefore is an ideal material to study the mechanism of freezing resistance of woody plants. Glucose-6-phosphate dehydrogenase (G6PDH) is the first and main regulated enzyme of the oxidative pentose phosphate pathway (OPPP), and it is a major source of reductant (NADPH) for biosynthetic processes and carbon skeletons for nucleotides synthesis. Moreover, its exepression is also involved in different abotic stresses. Therefore G6PDH playes important roles in the growth and development of plants. In the previous studies, it has been found that G6PDH activity was closely correlation with freezing resistance of P. suaveolens during freezing stress. In this present studies,PsG6PDH gene was cloned by RT-PCR and E-PCR from P. suaveolens and its structure and function was analyzed by bioinformatics. In addition, PsG6PDH was expressed in E. coli for verifying the integrity of its open reading frame (ORF), and then was transformed into tobacco. Finally, the changes in electrical conductity, MDA contents, SOD and POD activites as well as freezing resistance of transgenic tobacco plants with PsG6PDH were determined in order to explore the function of PsG6PDH expression. The main research conclusions were showed as follows:1. A tissue culture system of P. suaveolens was established. The optimal medium for inducing adventitious buds from fragrant poplar stem explants was modified MS (MMS) supplemented with 6-BA 0.5mg/l and NAA 0.1mg/l by orthogonal design. Shoots regenerated in vitro were obtained from propagated buds of explants and subcultured on MMS medium...