ARS | Publication request: The effect of iron limitation on the transcriptome and proteome of Pseudomonas fluorescens Pf-5

Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 18, 2012
Publication Date: June 18, 2012
Citation: Lim, C., Hassan, K.H., Tetu, S., Loper, J.E., Paulsen, I. 2012. The effect of iron limitation on the transcriptome and proteome of Pseudomonas fluorescens Pf-5. PLoS One. 7(6):e39139.

Interpretive Summary: Biological control provides a promising strategy for managing plant diseases but has not yet been utilized widely in agriculture due, in part, to unexplained variation in its success in managing disease. Our research goals are to identify sources of variation in biological control, and devise ways to make it more reliable. We focus on Pseudomonas fluorescens, which is a species of bacteria that occurs naturally on plant surfaces such as leaves and roots. Specifically, we focus on P. fluorescens strain Pf-5, which lives on plant seeds and roots, and protects the plant from infection by plant pathogens that live in the soil. Iron is a prevalent element in the soil, but it is in a form that is unavailable to bacteria like Pf-5. In this study, we determined the effects of iron limitation on the expression of all of the genes in Pf-5, including genes required for biological control. Several of the iron-regulated genes are involved in the production of compounds that are toxic to plant pathogens, including hydrogen cyanide and the the antibiotic 2,4-diacetylphloroglucinol. These data fit into an emerging picture of environmental factors controlling the biological control activity of Pf-5.

Technical Abstract: We investigated the transcriptomic and proteomic effects of iron limitation on Pf-5 by employing microarray and iTRAQ techniques, respectively. Analysis of this data revealed that molecular elements involved in iron homeostasis, including the pyoverdine and enantio-pyochelin biosynthesis clusters and a number of TonB-dependent receptor systems, were significantly up-regulated in response to iron limitation. In contrast, a gene cluster involved in flagellar biosynthesis was down-regulated and swarming motility of Pf-5 had reduced swarming motility in response to iron limitation.