title: The plant-growth-promoting bacterium Klebsiella sp. SBP-8 confers induced systemic tolerance in wheat (Triticum aestivum) under salt stress.
abstract: Plant-growth-promoting bacteria (PGPB) with 1-aminocyclopropane-1-carboxylatedeaminase (ACCD) activity can protect plants from the deleterious effects of abioticstressors. An ACCD bacterial strain, SBP-8, identified as Klebsiella sp., also having other plant-growth-promoting activities, was isolated from Sorghum bicolor growing in the desertregion of Rajasthan, India. ACCD activity of SBP-8 was characterized at biochemical, physiological, and molecular levels. The presence of AcdS, a structural gene for ACCD, was confirmed by the polymerase chain reaction. Strain SBP-8 showed optimum growth and ACCD activity at increased salt (NaCl) concentrations of up to 6%, indicating its potential to survive and associate with plants growing in saline soil. Inoculation of wheat plants with SBP-8 when grow in the presence of salt (150-200 mM) and temperature (30-40 °C) stressors resulted inamelioration of stress conditions by increasing plant biomass and chlorophyll content, and are duction in plant growth inhibition (10-100%) occurred due to salt and temperature stressors. Moreover, strain SBP-8 also caused Na(+) exclusion (65%) and increased uptake of K(+) (84.21%) in the host plant. This property can protect plants from adverse effects of Na(+) on plant growth and physiology. Thus, SBP-8 improves growth of the host plant and protects from salt stressors through more than one mechanism including an effect of ACCD activity and on K(+)/Na(+) ratio in plants. The colonization efficiency of strain SBP-8 was confirmedby CFU (colony-forming unit) count, microscopy, and ERIC-PCR based DNA-finger-printing approach. Therefore, and the use of efficient colonizing plant-growth-promoting bacteria may provideinsights into possible biotechnological approaches to decrease the impact of salinity and other stressors.
authors.affiliation: Department of Biological Sciences, Birla Institute of Technology and Science (BITS), Pilani 333031, Rajasthan, India.
authors.forename: Rajnish Prakash
authors.initials: RP
authors.lastname: Singh
authors.affiliation: Department of Biological Sciences, Birla Institute of Technology and Science (BITS), Pilani 333031, Rajasthan, India.
authors.forename: Prameela
authors.initials: P
authors.lastname: Jha
authors.affiliation: Department of Biological Sciences, Birla Institute of Technology and Science (BITS), Pilani 333031, Rajasthan, India. Electronic address: prabhatn.jha@gmail.com.
authors.forename: Prabhat Nath
authors.initials: PN
authors.lastname: Jha
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018533:Biomass; D002734:Chlorophyll / Q000032:analysis; D006358:Hot Temperature; D007194:India; D007709:Klebsiella / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D054712:Salinity; D055049:Salt Tolerance; D017422:Sequence Analysis, DNA; D014908:Triticum / Q000254:growth & development / Q000382:microbiology* / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D002734:Chlorophyll
keywords: ACC deaminase; ERIC–PCR; Induced systemic tolerance; Klebsiella sp; PGPR