Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/6/2008
Publication Date: 2/1/2009
Citation: Narayanan, N.N., Tasma, I.M., Grant, D.M., Shoemaker, R.C., Bhattacharyya, M.K. 2009. Identification of Candidate Signaling Genes Including Regulators of Chromosome Condensation 1 Protein Family Differentially Expressed in the Soybean - Phytophthora Sojae Interaction. Journal of Theoretical and Applied Genetics. 118(3):399-412. Interpretive Summary: Many millions of dollars are lost to soybean producers each year through stem and root rot. This loss could be better controlled if we knew more about the way soybean defends itself from the disease. The authors collected the gene messages produced by soybean immediately after infection with the root and stem rot pathogen. They compared these genes to genes expressed by soybean without pathogen infection. Using this approach they identified many unique genes that seemed to be involved in soybean's defense response. Many genes were known to be involved in plant response to pathogens, but many had no previously known function. This information will be important to researchers who are attempting to dissect the complex pathways plants utilize to mount defenses against diseases. This information may lead to new strategies for engineering disease resistance in soybean.
Technical Abstract: Stem and root rot caused by the oomycete pathogen, Phytopthora sojae, is a serious soybean disease. Use of Phytophthora resistance genes (Rps) in soybean cultivars has been very effective in controlling this pathogen. Resistance encoded by Rps genes is manifested through activation of defense responses. In order to identify candidate regulatory genes for expression of Phytophthora resistance in soybean, a cDNA library (Gm-c1084) was prepared from infected soybean etiolated hypocotyl tissues, and harvested two and four hours following P. sojae inoculation. An in silico comparison of 4,737 expressed sequence tags (ESTs) of this library with 152,000 ESTs originating from unstressed cDNA libraries resulted in identification of 206 genes, of which seven were P. sojae genes. Putative function of 83 of the 206 genes could not be predicted based on sequence comparison. Macroarray analyses led to identification of 114 soybean genes including 35 signaling-related genes and three P. sojae genes, transcripts of which were induced 1½-fold in P. sojae-infected tissues as compared to that in the water controls. Northern blot analyses confirmed the induction of five candidate regulatory genes, two novel p450 genes and one retrotransposon-like sequence that have showed 1½- or less fold transcript induction in infected tissues over that in water controls. Characterization of a cDNA library generated from P. sojae-infected tissues almost immediately following inoculation suggested the possible involvement of many signaling proteins in the expression defense-related pathways in the soybean-P. sojae interactions.