title: A Halotolerant BacteriumBacillus licheniformisHSW-16 Augments Induced Systemic Tolerance to Salt Stress in Wheat Plant (Triticum aestivum).
abstract: Certain plant growth promoting bacteria can protect associated plants from harmful effects of salinity. We report the isolation and characterization of 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase bacteriumBacillus licheniformisHSW-16 capable of ameliorating salt (NaCl) stress in wheat plants. The bacterium was isolated from the water of Sambhar salt lake, Rajasthan, India. The presence of ACC deaminase activity was confirmed by enzyme assay and analysis ofAcdSgene, a structural gene for ACC deaminase. Inoculation ofB. licheniformisHSW-16 protected wheat plants from growth inhibition caused by NaCl and increased plant growth (6-38%) in terms of root length, shoot length, fresh weight, and dry weight. Ionic analysis of plant samples showed that the bacterial inoculation decreased the accumulation of Na+content (51%), and increased K+(68%), and Ca2+content (32%) in plants at different concentration of NaCl. It suggested that bacterial inoculation protected plants from the effect of NaCl by decreasing the level of Na+in plants. Production of exopolysaccharide by theB. licheniformisHSW-16 can also protect from Na+by binding this ion. Moreover, application of test isolate resulted in an increase in certain osmolytes such as total soluble sugar, total protein content, and a decrease in malondialdehyde content, illustrating their role in the protection of plants. The ability ofB. licheniformisHSW-16 to colonize plant root surface was examined by staining the bacterium with acridine orange followed by fluorescence microscopy and polymerase chain reaction-based DNA finger printing analysis. These results suggested thatB. licheniformisHSW-16 could be used as a bioinoculant to improve the productivity of plants growing under salt stress.
authors.affiliation: Department of Biological Science, Birla Institute of Technology and Science Pilani, India.
authors.forename: Rajnish P
authors.initials: RP
authors.lastname: Singh
authors.affiliation: Department of Biological Science, Birla Institute of Technology and Science Pilani, India.
authors.forename: Prabhat N
authors.initials: PN
authors.lastname: Jha
keywords: ACC deaminase; AcdS; ERIC-PCR; exopolysaccharide (EPS); osmolytes; salt-stress