Molecular Cloning And Functional Verification Of NPR1Gene In Poplar

As the model plant in forest product, poplar is widely cultivated in the world becauseof high rate of growth, strong adaptability and high yield. However, there are variouspoplar diseases and traditional resistant measures are imperfect. Researches on resistancemechanism and molecular breeding are promising. Systemic acquired resistance (SAR) is aplant immune response that is usually induced by local infection to protect the plant againstbacterial, fungal and viral infections and it is recognized to provide efficientbroad-spectrum disease resistance. The non-expresser of pathogenesis-related gene1(NPR1) is a significant regulator of systemic acquired resistance in plants which inducesPR genes with triggering of SA or pathogens. Over-expression of NPR1results inenhanced bacterial and fungal resistance.In this study, two homologous poplar genes were identified by bioinformatics analysisand cloned from Populus deltoids cv. Nanlin95. A phylogenetic tree was generated fromalignments of PtNPR1protein sequences and NPR1-like genes in other plants. Multipleprotein alignments were also constructed to analyze the distribution of crucial domains. Atthe same time, the over-expression vector was constructed and transformed into poplar.Transformed plants were filtered by antibiotic and confirmed by PCR analysis. The mainresults are summarized as follow:(1) Two homologous poplar genes, PtNPR1.1(JQ231218) and PtNPR1.2(JF732893),were cloned.(2) Protein sequences and phylogentic analysis of PtNPR1.1and PtNPR1.2showedhigh homology with NPR1in Arabidopsis.(3) The PtNPR1.1-GFP fusion expression vector were constructed and expressed inArabidopsis mesophyll protoplasts, where it localized to the cytoplasm.(4) Analysis of transcription levels revealed expression patterns of PtNPR1.1andPtNPR1.2were non-tissue-specific expression and induced by exogenous SA.(5) Promoters of PtNPR1.1and PtNPR1.2were cloned and cis-element analysisrevealed that the PtNPR1promoters contain RAV1AAT and W-boxes motifs, both ofwhich are known to related to SA signal pathway.(6) The over-expression vector PBI121+PtNPR1.2was constructed and transformedinto “Nanlin95”.2transformed plants were obtained after screening.