Short Communication

Biology and Fertility of Soils

, Volume 45, Issue 6, pp 669-674

First online:

A diazotrophic, indole-3-acetic acid-producing endophyte from wild cottonwood

  • Gang XinAffiliated withDepartment of Civil and Environmental Engineering, University of WashingtonHydranautics
  • , Gengyun ZhangAffiliated withCollege of Forest Resources, University of Washington
  • , Jun Won KangAffiliated withCollege of Forest Resources, University of Washington
  • , James T. StaleyAffiliated withDepartment of Microbiology, University of Washington
  • , Sharon L. DotyAffiliated withCollege of Forest Resources, University of Washington Email author 

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An endophytic bacterium, wild poplar strain B (WPB), isolated from stems of wild cottonwood (Populus trichocarpa) was identified to Burkholderia vietnamiensis by analyzing the recA and rDNA genes. Phylogenetic analysis of the nifHDK cluster indicates that the WPB isolate shares high sequence similarity with known B. vietnamiensis strains. The nitrogenase activity of WPB was determined by a 15N2 incorporation assay and an acetylene reduction assay. WPB was also monitored for production of indole-3-acetic acid (IAA), a phytohormone which can promote plant growth, when incubated with l-tryptophan. In addition, its plant growth promotion capacity was assessed by inoculating the WPB strain onto Kentucky bluegrass in nitrogen-free medium. Compared to uninoculated control plants, the plants inoculated with WPB gained more dry weight (42%, p = 0.01) and more nitrogen content (37%, p = 0.04) in 50 days.


Diazotrophic endophyte Poplar trees Plant growth promotion Burkholderia vietnamiensis IAA Phylogenetic analysis Turf grass Nitrogen fixation Populus Auxin Endophytes