title: Phytohormone signaling pathway analysis method for comparing hormone responses in plant-pest interactions.
abstract: BACKGROUND
  Phytohormones mediate plant defense responses to pests and pathogens. In particular, the hormones jasmonic acid, ethylene, salicylic acid, and abscisic acid have been shown to dictate and fine-tune defense responses, and identification of the phytohormone components of a particular defense response is commonly used to characterize it. Identification of phytohormone regulation is particularly important in transcriptome analyses. Currently there is no computational tool to determine the relative activity of these hormones that can be applied to transcriptome analyses in soybean.
  
  
  RESULTS
  We developed a pathway analysis method that provides a broad measure of the activation or suppression of individual phytohormone pathways based on changes in transcript expression of pathway-related genes. The magnitude and significance of these changes are used to determine a pathway score for a phytohormone for a given comparison in a microarray experiment. Scores for individual hormones can then be compared to determine the dominant phytohormone in a given defense response. To validate this method, it was applied to publicly available data from previous microarray experiments that studied the response of soybean plants to Asian soybean rust and soybean cyst nematode. The results of the analyses for these experiments agreed with our current understanding of the role of phytohormones in these defense responses.
  
  
  CONCLUSIONS
  This method is useful in providing a broad measure of the relative induction and suppression of soybean phytohormones during a defense response. This method could be used as part of microarray studies that include individual transcript analysis, gene set analysis, and other methods for a comprehensive defense response characterization.
authors: Bioinformatics and Computational Biology Program, Iowa State University, Ames, IA 50011, USA.
authors: Matthew E
authors: ME
authors: Studham
authors: Gustavo C
authors: GC
authors: MacIntosh
mesh_terms: D000818:Animals; D001487:Basidiomycota / Q000472:pathogenicity / Q000502:physiology; D018506:Gene Expression Regulation, Plant / Q000276:immunology*; D054884:Host-Pathogen Interactions; D009348:Nematoda / Q000472:pathogenicity / Q000502:physiology; D020411:Oligonucleotide Array Sequence Analysis; D010935:Plant Diseases; D010937:Plant Growth Regulators / Q000096:biosynthesis / Q000235:genetics*; D015398:Signal Transduction / Q000235:genetics* / Q000276:immunology; D013025:Glycine max / Q000235:genetics* / Q000276:immunology / Q000382:microbiology / Q000469:parasitology; D059467:Transcriptome
chemical_list: D010937:Plant Growth Regulators