title: The bacterial superoxide dismutase and glutathione reductase are crucial for endophytic colonization of rice roots by Gluconacetobacter diazotrophicus PAL5.
abstract: Gluconacetobacter diazotrophicus is an aerobic diazotrophic plant-growth-promoting bacterium isolated from different gramineous plants. We showed that reactive oxygen species (ROS) were produced at early stages of rice root colonization, a typical plant defense response against pathogens. The transcription of the pathogen-related-10 gene of the jasmonic acid (JA) pathway but not of the PR-1 gene of the salicylic acid pathway was activated by the endophytic colonization of rice roots by G. diazotrophicus strain PAL5. Quantitative polymerase chain reaction analyses showed that, at early stages of colonization, the bacteria upregulated the transcript levels of ROS-detoxifying genes such as superoxide dismutase (SOD) and glutathione reductase (GR). To proof the role of ROS-scavenging enzymes in the colonization and interaction process, transposon insertion mutants of the SOD and GR genes of strain PAL5 were constructed. The SOD and GR mutants were unable to efficiently colonize the roots, indicated by the decrease of tightly root-associated bacterial cell counts and endophytic colonization and by fluorescence in situ hybridization analysis. Interestingly, the mutants did not induce the PR-10 of the JA-pathway, probably due to the inability of endophytic colonization. Thus, ROS-scavenging enzymes of G. diazotrophicus strain PAL5 play an important role in the endophytic colonization of rice plants.
authors: German Research Center for Environmental Health, Neuherberg, Germany. campbell-alqueres@helmholtz-muenchen.de
authors: Sylvia
authors: S
authors: Alquéres
authors: Carlos
authors: C
authors: Meneses
authors: Luc
authors: L
authors: Rouws
authors: Michael
authors: M
authors: Rothballer
authors: Ivo
authors: I
authors: Baldani
authors: Michael
authors: M
authors: Schmid
authors: Anton
authors: A
authors: Hartmann
mesh_terms: D003001:Cloning, Molecular; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D041821:Gluconacetobacter / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D005980:Glutathione Reductase / Q000235:genetics / Q000378:metabolism*; D017404:In Situ Hybridization, Fluorescence; D012275:Oryza / Q000382:microbiology*; D018517:Plant Roots / Q000382:microbiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species; D060888:Real-Time Polymerase Chain Reaction; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*; D013559:Symbiosis; D013997:Time Factors
chemical_list: D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase; D005980:Glutathione Reductase