Cloning And Sequencing Analysis Of NADH Dehydrogenase Genes From Chloroplast Of Poplar Tree

Conserved sequence of NADH dehydrogenase gene from Arabidopsis thaliana was used as a probe to search EST database and to assemble the sequence of NADH dehydrogenase gene for poplar using a bioinformatics software. Then, the chloroplast genome of poplar was cloned by designing a PCR degenerate primer. Based on the assembled poplar EST sequence, a new primer was designed by sequence assembly to obtain complete cDNA sequence of NADH dehydrogenase gene from poplar via RT-PCR. The results showed that the amino acid sequence of this gene was consisted of1,058base pairs. Its non-coding sequences at5’and3’ends were100and202base pairs respectively. Its open reading frame consisted of756base pairs, coding252amino-acid residues and with a molecular weight of28.4kD. The authors deduced that it should be the sequence for ndhK subunit, and therefore was named as YsDDRA. The analysis of its coded protein via EXPASY database showed YsDDRA had multiple casein kinase Ⅱ phosphorylation sites and N-glycation sites. Thus, it was expected that the coded protein of this sequence would go through processing and modification procedures after translation to be a functional peptide when being synthesized. Previous studies found the ndhk subunit was relevant to cyclic electron transport of PSI system, which could enhance the salt resistance of plants. Therefore, the results of this study will be fundamental in molecular improvement and discovery of molecular mechanism of salt resistance of poplar.