title: Distinct changes in soybean xylem sap proteome in response to pathogenic and symbiotic microbe interactions.
abstract: BACKGROUND
  Plant systemic signaling characterized by the long distance transport of molecules across plant organs involves the xylem and phloem conduits. Root-microbe interactions generate systemic signals that are transported to aerial organs via the xylem sap. We analyzed the xylem sap proteome of soybean seedlings in response to pathogenic and symbiotic interactions to identify systemic signaling proteins and other differentially expressed proteins.
  
  
  RESULTS
  We observed the increase of a serine protease and peroxidase in the xylem sap in response to Phytophthora sojae elicitor treatment. The high molecular weight fraction of soybean xylem sap was found to promote the growth of Neurospora crassa in vitro at lower concentrations and inhibit growth at higher concentrations. Sap from soybean plants treated with a P. sojae elicitor had a significantly higher inhibitory effect than sap from control soybean plants. When soybean seedlings were inoculated with the symbiont Bradyrhizobium japonicum, the abundance of a xyloglucan transendoglycosyl transferase protein increased in the xylem sap. However, RNAi-mediated silencing of the corresponding gene did not significantly affect nodulation in soybean hairy root composite plants.
  
  
  CONCLUSIONS
  Our study identified a number of sap proteins from soybean that are differentially induced in response to B. japonicum and P. sojae elicitor treatments and a majority of them were secreted proteins.
authors.affiliation: Donald Danforth Plant Science Center, St Louis, MO, 63132, USA. Senthil.Subramanian@sdstate.edu
authors.forename: Senthil
authors.initials: S
authors.lastname: Subramanian
authors.forename: Un-Haing
authors.initials: UH
authors.lastname: Cho
authors.forename: Carol
authors.initials: C
authors.lastname: Keyes
authors.forename: Oliver
authors.initials: O
authors.lastname: Yu
mesh_terms: D020369:Bradyrhizobium / Q000254:growth & development; D015180:Electrophoresis, Gel, Two-Dimensional; D018506:Gene Expression Regulation, Plant; D054884:Host-Pathogen Interactions / Q000235:genetics*; D010838:Phytophthora / Q000254:growth & development; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D020543:Proteome / Q000378:metabolism*; D013025:Glycine max / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D013559:Symbiosis / Q000235:genetics*; D053719:Tandem Mass Spectrometry; D052584:Xylem / Q000378:metabolism* / Q000382:microbiology
chemical_list: D020543:Proteome