title: Improvement of growth, fruit weight and early blight disease protection of tomato plants by rhizosphere bacteria is correlated with their beneficial traits and induced biosynthesis of antioxidant peroxidase and polyphenol oxidase.
abstract: Five plant growth promoting rhizobacteria (PGPRs) of different genera, newly isolated from healthy tomato rhizosphere, were characterized with phosphate solubilizing and root colonizing ability. Treatment with these isolates recorded a significant increase in seed germination and seedling vigor as well as tomato growth and fruit weight which might be partly attributed to the ability of the PGPRs to produce IAA and enhance nutrient uptake and chlorophyll content in treated plants. More importantly, a strong protection against early blight disease was observed in PGPR-pretreated tomato plants infected with Alternaria solani which is in accordance with the presence of siderophores, HCN, chitinase and glucanase in the isolated PGPRs. Additionally, a significantly enhanced accumulation of antioxidant peroxidase (POX) and polyphenol oxidase (PPO) enzymes was observed in the PGPR-pretreated plants with or without pathogen infection in comparison with water or pathogen control. Notably, the highest increase in POX and PPO accumulations was recorded in tomato plants raised from seeds primed with TN_Vel-35 strain. A significant upregulation of POX and PPO in tomato plants subjected to similar treatment with TN_Vel-35 versus respective control was also noticed, further strengthening that the PGPR-induced POX and PPO biosyntheses also contribute to PGPR-mediated protection against early blight disease in tomato plants.
authors.affiliation: Applied Plant Pathology Laboratory, Department of Studies in Botany, University of Mysore, Manasagangotri, Mysore 570 006, Karnataka, India.
authors.forename: Anupama
authors.initials: A
authors.lastname: Narendra Babu
authors.affiliation: Laboratory of Plant and Microbe Interactions, Department of Studies in Biotechnology and Microbiology, Karnatak University, Dharwad 580 003, Karnataka, India.
authors.forename: Sudisha
authors.initials: S
authors.lastname: Jogaiah
authors.affiliation: Laboratory of Molecular Plant Pathology, Department of Biological and Environmental Sciences, Faculty of Agriculture, Yamaguchi University, Yamaguchi, Japan.
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Ito
authors.affiliation: Applied Plant Pathology Laboratory, Department of Studies in Botany, University of Mysore, Manasagangotri, Mysore 570 006, Karnataka, India. Electronic address: dr.knamruthesh@botany.uni-mysore.ac.in.
authors.forename: Amruthesh
authors.initials: A
authors.lastname: Kestur Nagaraj
authors.affiliation: Signaling Pathway Research Unit, RIKEN Center for Sustainable Resource Science, 1-7-22, Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan. Electronic address: son.tran@riken.jp.
authors.forename: Lam-Son Phan
authors.initials: LS
authors.lastname: Tran
mesh_terms: D004156:Catechol Oxidase / Q000235:genetics / Q000378:metabolism*; D005638:Fruit / Q000235:genetics / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology*; D018551:Solanum lycopersicum / Q000235:genetics / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology*; D008969:Molecular Sequence Data; D009195:Peroxidase / Q000235:genetics / Q000378:metabolism*; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology*; D058441:Rhizosphere
chemical_list: D004156:Catechol Oxidase; D009195:Peroxidase
keywords: Defense-related enzyme; Induced systemic protection; Nutrients uptake; Plant growth promoting rhizobacteria; Plant growth promotion; Tomato early blight