Date of Award


Degree Type


Degree Name

Master of Science




Dr. George Lazarovits

Second Advisor

Dr. Kenneth Conn

Third Advisor

Dr. Perveiz Abbasi


Burkholderia phytofιrmans strain PsJN has been demonstrated to consistently promote plant growth under tissue culture conditions. The response of inoculated plants, however, can be highly variable under greenhouse or field conditions. In this study I set out to systematically examine how bacterial root colonization affects plant growth promotion. To achieve that goal, the regular potato explant bioassay was modified for better accuracy and efficiency and a genetically modified strain of PsJN was created with the gfp gene integrated into the genome for quantitative detection. Using competitions by a non-plant-growth-promoting mutant or a non-related bacterium Delftia acidovorans, PsJN’s population was manipulated in explants and results consistently showed a positive relationship between the extent of growth promotion by PsJN and the initial bacterial population established on the bioassay system, the roots, or the stems. This study also examined the possibility of using other microorganisms to enhance PsJN’s ability to promote plant growth.



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