Comparative effects of wild type Stenotrophomonas maltophilia and its indole acetic acid-deficient mutants on wheat.
The present investigation evaluated the role of Stenotrophomonas maltophilia and its IAA-deficient mutant on soil health and plant growth under salinity stress in the presence of tryptophan. In the first phase, S. maltophilia isolated from roots of the halo- phytic herb, Cenchrus ciliaris was used as bio-inoculant on wheat grown in saline sodic soil. A field experiment was conducted at Soil Salinity Research Institute during 2010-2011. Treatments included seed inoculation with S. maltophilia with or without tryptophan; uninoculated untreated plants were taken as control. An aqueous solution of tryptophan was added to rhizosphere soil at 1 μg l(_1) after seed germination. Inoculation with S. maltophilia significantly increased soil organic matter, enhanced (20-30%) availability of P, K, Ca and NO3 -N and decreased Na content and electrical conductivity of rhizosphere soil. Plant height, fresh weight, proline and phytohormone content of leaves were increased 30-40% over the control. Activities of superoxide dismutase (SOD) and peroxidase (POD) were 40-50% higher than control. Addition of tryptophan further augmented (10-15%) growth parameters, whereas NO3 -N, P, K and Ca content, proline content and SOD and POD increased 20-30%. In a second phase, indoleacetic acid (IAA)-deficient mutants of S. maltophilia were constructed and evaluated for conversion of tryptophan to IAA at the University of Calgary, Canada, during 2013-2014. About 1800 trans-conjugants were constructed that were unable to produce IAA in the presence of tryptophan. The results suggest that tryptophan assisted S. maltophilia in the amelioration of salt stress, and that IAA played positive role in induction of salt tolerance.
Department of Plant Sciences, Quaid-i-Azam University, Islamabad, Pakistan.
T U
TU
Hassan
Department of Plant Sciences, Quaid-i-Azam University, Islamabad, Pakistan.
A
A
Bano
D000040:Abscisic Acid / Q000378:metabolism; D005875:Gibberellins / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism; D007477:Ions / Q000032:analysis / Q000378:metabolism; D016254:Mutagenesis, Insertional; D009195:Peroxidase; D010937:Plant Growth Regulators / Q000378:metabolism*; D018515:Plant Leaves / Q000254:growth & development / Q000382:microbiology / Q000502:physiology; D018517:Plant Roots / Q000254:growth & development / Q000382:microbiology / Q000502:physiology; D058441:Rhizosphere; D054712:Salinity; D055049:Salt Tolerance; D012639:Seeds / Q000254:growth & development / Q000382:microbiology / Q000502:physiology; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D020615:Stenotrophomonas maltophilia / Q000235:genetics / Q000502:physiology*; D013482:Superoxide Dismutase; D014908:Triticum / Q000254:growth & development / Q000382:microbiology* / Q000502:physiology
D005875:Gibberellins; D007210:Indoleacetic Acids; D007477:Ions; D010937:Plant Growth Regulators; D012987:Soil; C030737:indoleacetic acid; D000040:Abscisic Acid; C007842:gibberellic acid; D009195:Peroxidase; D013482:Superoxide Dismutase
IAA modulation; IAA-deficient mutant; S. maltophilia; sodium absorption ratio; transposon mutagenesis