Production of indole-3-acetic acid in the plant-beneficial strain Pseudomonas chlororaphis O6 is negatively regulated by the global sensor kinase GacS.
Certain plant growth-promoting bacteria, such as Pseudomonas fluorescens 89B61 and Bacillus pumilus SE34, secreted high levels of indole-3-acetic acid (IAA) in tryptophan-amended medium in stationary phase as determined by chromogenic analysis and high-performance liquid chromatography. Two other growth-promoting strains, P. chlororaphis O6 and Serratia marcescens 90-166, did not produce these high levels of IAA. However, when the gacS mutant of P. chlororaphis O6 was grown in tryptophan-supplemented medium, IAA was detected in culture filtrates. IAA production by the gacS mutant in P. chlororaphis O6 was repressed in the tryptophan medium by complementation with the wild-type gacS gene. Thus, the global regulatory Gac system in P. chlororaphis O6 acts as a negative regulator of IAA production from trypophan.
Kang
Beom Ryong
BR
Agricultural Plant Stress Research Center and Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 500-757, Korea,
Yang
Kwang Yeol
KY
Cho
Baik Ho
BH
Han
Tae Ho
TH
Kim
In Seon
IS
Lee
Myung Chul
MC
Anderson
Anne J
AJ
Kim
Young Cheol
YC
D001426:Bacterial Proteins / Q000235:genetics*; D003470:Culture Media / Q000737:chemistry; D007210:Indoleacetic Acids / Q000378:metabolism*; D018517:Plant Roots / Q000254:growth & development / Q000382:microbiology*; D011549:Pseudomonas / Q000378:metabolism*; D014026:Nicotiana / Q000254:growth & development; D014157:Transcription Factors / Q000235:genetics*; D014364:Tryptophan / Q000378:metabolism
D001426:Bacterial Proteins; D003470:Culture Media; D007210:Indoleacetic Acids; D014157:Transcription Factors; C030737:indoleacetic acid; D014364:Tryptophan; C074165:lemA protein, bacterial