title: Effects of Pseudomonas aureofaciens 63-28 on defense responses in soybean plants infected by Rhizoctonia solani.
abstract: The objective of this work was to investigate the ability of the plant growth-promoting rhizobacterium Pseudomonas aureofaciens 63-28 to induce plant defense systems, including defense-related enzyme levels and expression of defense-related isoenzymes, and isoflavone production, leading to improved resistance to the phytopathogen Rhizoctonia solani AG-4 in soybean seedlings. Seven-dayold soybean seedlings were inoculated with P. aureofaciens 63-28, R. solani AG-4, or P. aureofaciens 63-28 plus R. solani AG-4 (P+R), or not inoculated (control). After 7 days of incubation, roots treated with R. solani AG-4 had obvious damping-off symptoms, but P+R-treated soybean plants had less disease development, indicating suppression of R. solani AG-4 in soybean seedlings. Superoxide dismutase (SOD) and catalase (CAT) activities of R. solani AG-4-treated roots increased by 24.6% and 54.0%, respectively, compared with control roots. Ascorbate peroxidase (APX) and phenylalanine ammonia lyase (PAL) activities of R. solani AG-4-treated roots were increased by 75.1% and 23.6%, respectively. Polyphenol oxidase (PPO) activity in soybean roots challenged with P. aureofaciens 63-28 and P+R increased by 25.0% and 11.6%, respectively. Mn-SOD (S1 band on gel) and Fe-SOD (S2) were strongly induced in P+R-treated roots, whereas one CAT (C1) and one APX (A3) were strongly induced in R. solani AG-4- treated roots. The total isoflavone concentration in P+Rtreated shoots was 27.2% greater than the control treatment. The isoflavone yield of R. solani AG-4-treated shoots was 60.9% less than the control.
authors.affiliation: Division of Applied Bioscience and Biotechnology, Institute of Agricultural Science and Technology, Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Woo-Jin
authors.initials: WJ
authors.lastname: Jung
authors.forename: Ro-Dong
authors.initials: RD
authors.lastname: Park
authors.forename: Fazli
authors.initials: F
authors.lastname: Mabood
authors.forename: Alfred
authors.initials: A
authors.lastname: Souleimanov
authors.forename: Donald
authors.initials: D
authors.lastname: L Smith
mesh_terms: D018506:Gene Expression Regulation, Plant; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology / Q000382:microbiology*; D010940:Plant Proteins / Q000235:genetics / Q000276:immunology; D018517:Plant Roots / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D011549:Pseudomonas / Q000502:physiology*; D012232:Rhizoctonia / Q000502:physiology*; D013025:Glycine max / Q000201:enzymology / Q000235:genetics / Q000276:immunology* / Q000382:microbiology*
chemical_list: D010940:Plant Proteins