Submitted to: International Plant Growth Promoting Rhizobacteria Workshop
Publication Type: Abstract Only
Publication Acceptance Date: April 15, 2009
Publication Date: May 17, 2009
Citation: Hassan, K., Paulsen, I., Johnson, A., Ren, Q., Shaffer, B.T., Loper, J.E. 2009. The transcriptomic fingerprint of the Pseudomonas fluorescens Pf-5 GacS/GacA signal transduction system. International Plant Growth Promoting Rhizobacteria Workshop. p. 84. Technical Abstract: A whole genome oligonucleotide microarray was used to assess the global transcriptomic consequences of a gacA knock-out mutation in P. fluorescens Pf-5. Modest changes to the P. fluorescens Pf-5 transcriptome were observed during early exponential growth phase in the gacA null mutant. In contrast, gacA inactivation resulted in profound changes in the transcriptome during early stationary growth phase. For example, transcription of genes involved in the production of hydrogen cyanide, pyoluteorin, and the extracellular protease AprA were underexpressed in the gacA knockout mutant, whereas the transcription of genes functioning in iron uptake and iron uptake regulation, including a large number of related extra-cytoplasmic function sigma factors, were significantly higher in the gacA mutant than in wild-type P. fluorescens. Further notable effects of gacA inactivation were observed in the transcription of genes encoding components of a type VI secretion system and cytochrome C oxidase subunits. Additionally, the transcription of genes within several previously undescribed putative biosynthetic operons was highly modulated by gacA inactivation. These results provide insight into characterized GacS/GacA-controlled phenotypes and highlight a range of novel genes and gene clusters in the genome of P. fluorescens Pf-5.