title: Characterization of the early response of the orchid, Phalaenopsis amabilis, to Erwinia chrysanthemi infection using expression profiling.
abstract: Erwinia chrysanthemi is a devastating bacterial pathogen in Phalaenopsis amabilis and causes soft-rotting disease by secretion of cell wall-degrading enzymes. However, the molecular mechanisms underlying the interaction of P. amabilis with E. chrysanthemi remain elusive. In this study, early molecular events of the plant in response to the pathogen attack were investigated. The alteration in reactive oxygen species accumulation and peroxidase activity occurred at the site of infection. Subsequently, a systematic sequencing of expressed sequence tags (ESTs) using suppression subtractive hybridization (SSH) was performed to obtain the first global picture of the assembly of genes involved in the pathogenesis. The majority of the SSH clones showed a high identity with genes coding for proteins that have known roles in redox homeostasis, responses to pathogens and metabolism. A notable number of the SSH clones were those encoding WRKY, MYB and basic leucine zipper transcription factors, indicating the stimulation of intracellular signal transduction. An orchid gene encoding trans-2-enoyl-CoA reductase (ECR) was the most abundant transcripts in the EST library. ECR is an enzyme catalyzing the very long chain fatty acids (VLCFAs) biosynthesis, and the full-length cDNA of the ECR gene (PaECR1) was obtained. Functional analysis of PaECR1 was conducted by virus-induced gene silencing to knock down the gene expression in P. amabilis. The PaECR1-silenced plants were more susceptible to E. chrysanthemi infection, implying potential roles for VLCFAs in the pathogenesis. In summary, the pathogen-responsive gene expression profiles facilitated a more comprehensive view of the molecular events that underlie this economically important plant-pathogen interaction.
authors.affiliation: Department of Biology, National Changhua University of Education, Changhua, Taiwan.
authors.forename: Shih-Feng
authors.initials: SF
authors.lastname: Fu
authors.forename: Tsung-Mu
authors.initials: TM
authors.lastname: Tsai
authors.forename: Ying-Ru
authors.initials: YR
authors.lastname: Chen
authors.forename: Ching-Pei
authors.initials: CP
authors.lastname: Liu
authors.forename: Lin-June
authors.initials: LJ
authors.lastname: Haiso
authors.forename: Li-Hsin
authors.initials: LH
authors.lastname: Syue
authors.forename: Hsin-Hung
authors.initials: HH
authors.lastname: Yeh
authors.forename: Hao-Jen
authors.initials: HJ
authors.lastname: Huang
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism / Q000382:microbiology; D016974:Dickeya chrysanthemi / Q000472:pathogenicity*; D004789:Enzyme Activation; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling / Q000379:methods*; D018506:Gene Expression Regulation, Plant; D055785:Gene Knockdown Techniques / Q000379:methods; D020868:Gene Silencing; D017343:Genes, Plant; D006706:Homeostasis; D054884:Host-Pathogen Interactions; D008969:Molecular Sequence Data; D029595:Orchidaceae / Q000235:genetics / Q000378:metabolism / Q000382:microbiology*; D010084:Oxidation-Reduction; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000235:genetics / Q000378:metabolism; D009195:Peroxidase / Q000235:genetics / Q000378:metabolism; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D009195:Peroxidase; D044925:Oxidoreductases Acting on CH-CH Group Donors; C434934:trans-2-enoyl-CoA reductase (NADPH)