Poplar Pathogen Defense-related Gene Cloning And Functional Analysis

Compared with the poplar genome database JGI P. trichocarpa v1.0 (http://genome. jgi-psf. org/Poptr1/Poptr1. home. html), thirty-eight differential display sequences were annotated newly. Eleven sequences were found to be associated with plant defense or were functionally unknown. Upon examination by real-time quantitative PCR, two of 11 differential display (DD) sequences - 69-III-4 and 69-II-6 -were found to be induced intensively by the pathogen. According to the genome annotation database for the species, 69-III-4 is associated with lipoxygenase (LOX) and 69-II-6 refers to a DNA damage-repair/toleration protein. In this study, we set up a sort of simple real time RT-PCR method and analyzed the reliability using ANOVA method .In the present study, we cloned two lipoxygenase genes, PdLOX1 and PdLOX2 (GenBank accession no. DQ131178, DQ131179). from Populus deltoides cv. 'Lux' (1-69/55). A prokaryotic expression analysis of PdLOX1 and PdLOX2 revealed that the encoded exogenous proteins were identical to the predicted molecular weights and possessed the expected lipoxygenase activities. Chromatogram analysis indicated that the two lipoxygenase mainly possess 13-LOX activity. Phylogenetic analysis of the derived amino acid sequences of known lipoxygenases revealed that PdLOX1 and PdLOX2 were members of the type 2 13-LOX family of genes. This class of lipoxygenases is known to be involved in biotic and abiotic stress. Using real-time RT-PCR, we evaluated PdLOX1 and PdLOX2 expression following exposure to a Poplar fungal pathogen (Marssonina brunnea f. sp. Multigermtubi), mechanical injury, methyl jasmonate (MeJA), or salicylic acid (SA). We report that both PdLOX1 and PdLOX2 expression levels were increased following exposure to M. brunnea f. sp. Multigermtubi, with the pathogen exerting a relatively stronger influence on PdLOX1 expression. Furthermore, expression levels of the two genes were also up-regulated by mechanical damage and exposure to MeJA. In contrast, both PdLOX1 and PdLOX2 expression was down-regulated by SA treatment. We propose that the two novel lipoxygenases may play an important role in Poplar resistance to biotic and abiotic stress. According DD sequences and poplar genome database, we cloned a DNA damage-repair/toleration, PdDRT100. A prokaryotic expression analysis of PdDRT100 revealed that complementation of E. coli reck Mutation. PdDRT100 were increased following exposure to fungal pathogen and SA. In present study, we cloned a PGIP gene homolog from Populus deltoids.The sequence was highly homologous to Arabidopsis PGIP1, 2. Candidate genes in the QTLs involved in poplar black spot disease were identified based on populus gemone database. Using real-time RT-PCR, we analyzed expression level of 19 candidate gene in I-69(resistance)...