Effect of iron concentration on the growth rate of Pseudomonas syringae and the expression of virulence factors in hrp-inducing minimal medium.
Although chemically defined media have been developed and widely used to study the expression of virulence factors in the model plant pathogen Pseudomonas syringae, it has been difficult to link specific medium components to the induction response. Using a chemostat system, we found that iron is the limiting nutrient for growth in the standard hrp-inducing minimal medium and plays an important role in inducing several virulence-related genes in Pseudomonas syringae pv. tomato DC3000. With various concentrations of iron oxalate, growth was found to follow Monod-type kinetics for low to moderate iron concentrations. Observable toxicity due to iron began at 400 microM Fe(3+). The kinetics of virulence factor gene induction can be expressed mathematically in terms of supplemented-iron concentration. We conclude that studies of induction of virulence-related genes in P. syringae should control iron levels carefully to reduce variations in the availability of this essential nutrient.
Kim
Beum Jun
BJ
School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853, USA.
Park
Joon Ho
JH
Park
Tai Hyun
TH
Bronstein
Philip A
PA
Schneider
David J
DJ
Cartinhour
Samuel W
SW
Shuler
Michael L
ML
D003470:Culture Media / Q000737:chemistry; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D006133:Growth Substances / Q000494:pharmacology*; D007501:Iron / Q000494:pharmacology*; D008962:Models, Theoretical; D044224:Pseudomonas syringae / Q000254:growth & development* / Q000378:metabolism* / Q000502:physiology; D037521:Virulence Factors / Q000096:biosynthesis*
D003470:Culture Media; D006133:Growth Substances; D037521:Virulence Factors; D007501:Iron