Submitted to: Annual International Plant & Animal Genome Conference
Publication Type: Abstract only
Publication Acceptance Date: 10/1/2008
Publication Date: 1/10/2009
Publication URL: www.intl-pag.org/
Citation: Osman, R., Clough, S.J. 2009. Differences and Similarities of Soybean Defense-Related Genes Suppressed by Pathogenic and Symbiotic Bacteria [abstract]. Annual International Plant and Animal Genome Conference. January 10-14, 2009, San Diego, CA. Available: http://www.intl-pag.org/pag/17/abstracts/W52_PAGXVII_364.html Interpretive Summary:
Technical Abstract: Bacterial effector proteins secreted through type III secretion systems (T3SS) play a crucial role in establishing plant and human diseases. Type III effectors have been shown to trigger defense responses when recognized by resistant plants, and to suppress defense responses in susceptible host plants. Here, we are reporting effects of T3SS effectors in a soybean-pathogen interaction (Pseudomonas syringae pv. glycinae) and a soybean-symbiont interaction (Bradyrhizobium japonicum). The pathogenic interaction was designed to examine the hypothesis that P. syringae pv. glycinae carrying the avirulence gene avrB suppresses defense responses in a soybean host that lacks the corresponding R gene, RPG2. The symbiotic interaction was designed to address the hypothesis that B. japonicum carrying a functional T3SS suppresses the soybean host defense to establish symbiosis. In the pathogenic interaction, gene expression profiling using in-house soybean oligo microarrays, consisting of approximately 38,000 different genes, indicated that defense genes, transcription factors, genes involved in the phenylpropanoid pathway and signal transduction components were down-regulated in soybean susceptible plants when avrB was present compared to avrB-minus pathogen. In the symbiotic interaction, Affymetrix gene chip analysis of soybean root-hair response to a T3SS mutant and wild-type B. japonicum versus mock inoculation at 6, 12, and 18 hours post treatment identified 3051 transcripts as being differentially expressed. Preliminary analysis of these results identified transcripts related to redox, proteases, channels, ethylene, calcium, and glutathione as being more abundant in root hairs challenged with the T3SS mutant than wild type. Further details of differences and similarities of defense–related genes suppressed by pathogenic and symbiotic bacteria will be presented.