Analysis Of Differentially Expressed Genes In Stem And Leaf Of Populus Simonii×P.nigra

Populus simonii×P.nigra is the hybrid species from the crossing of Populus simonii and Populus nigra, because it's quickly growing and good wood quanlity, it was widely used for board materials and paper industry. For the understanding of wood formation mechanism of poplar, the different expressed genes between stems and leaves of Populu simonii×P. nigra were detected by the cDNA-AFLP method. Results showed that a total of 4192 gene fragments were amplified and observed by Licor-4300 DNA analyzer from the cDNA of stems and leaves, a total of 2275 gene fragments were differential displayed genes between stems and leaves. In which 1039 gene fragments were from stem, and 1236 gene fragments were from leaves. A total of 402 differentially expressed gene fragments were found by silver staining method, and 217 unique sequences were obtained and deposited in GenBank as accession number JG567410-JG567590 and GW863844-GW863890. Blast-x analysis showed that 165 gene fragments encoded know function proteins, and 25 gene fragments encoded unknown function proteins and 27 gene fragments did not found homologous sequence in GenBank. Based on their putative protein functions, the 166 gene fragments were further classified into 12 functional categories which including metabolism, lignin biosynthetic process, transport, microtubule polymerization, cell wall biogenesis/degradation, cellulose biosynthesis, catabolic process, transcription regulation, signal transduction, protein biosynthesis, photosynthesis and other.Based on the analysis of bioinformation found that gene fragment of S-03 was laccase gene associated lignin synthesis, which share higher homologous with other gene, the 1413 bp cDNA fragment of laccase gene in Populus simonii×P. nigra named PsnLAC was obtained using RT-PCR, which including a 1020 bp open reading frame, and encoding 339 amino acid residues sharing higher homology with other plant laccase genes. The PsnLAC gene was introduced into tobacco by Atumefaciens mediated transformation, and PCR and RT-PCR analysis indicated that PsnLAC gene was integrated into tobacco genome, contrast untransformed plant, the transformants content higher lignin in tobacco stems, and could increase tolerance to salt stress.