Project description:We aim to understand the global transcriptional response of hybrid poplar NM6 (Populus nigra x Populus maximoviczii) to infection by two biotrophic Melampsora fungi, M. larici-populina and M. medusae f. sp. deltoidae separately and simultanously. Transcript profilling revealed 699 differentially expressed genes whose expression level was equal or higher than 2-fold between infected and noninfected tissues. In the mixed infection, our results showed an additive response of the two pathogens. Genes regulated as a result of Melampsora infection were generally induced and mainly involved in primary/secondary metabolism that include cell wall reinforcement and lignification, defense-related processes like pathogenesis-related and stress response, signal perception and transduction mechanisms and regulation of transcription. Keywords: Stress response
Project description:To investigate the function of poplar WRKY23, we generated PtWRKY23-overexpressing and -underexpressing (RNAi) plants. Transgenic plants were inoculated with Melampsora rust or mock-inoculated for assessment of rust-resistance and for gene expression profiling using the poplar Affymetrix GeneChip® to study the consequences of PtWRKY23 overexpression and underexpression. Transcriptome analysis of PtWRKY23 overexpressors revealed a significant overlap with the Melampsora-infection response. Transcriptome analysis also indicated that PtWRKY23 affects redox homeostasis and cell wall-related metabolism. Experiment Overall Design: Leaf discs from wildtype, WRKY23-overexpressor and WRKY23-RNAi plants were inoculated with Melampsora medusae f. sp. tremuloidae (Mmt) or were mock-inoculated (control). At five days post-inoculation, tissues were harvested for RNA extraction and hybridization to Affymetrix GeneChips®. Three biological replications were performed for each line and each inoculation or mock-inoculation. A total of 15 Affymetrix GeneChips® were used in this study. Data for the WRKY23-overexpressor plants were processed separately from the data for the Mmt-inoculated WRKY23-RNAi plants. The raw data for the Mmt-inoculated wildtype plants were the same in both cases. Experiment Overall Design: This part of the study includes 12 RNA samples consisting of three biological replicates for each of the mock-inoculated or Mmt-inoculated WT and WRKY23-overexpressing plants.