Changes in the transcriptome of Azospirillum brasilense, sp7 in response to ethylene

The goal of this study was to determine the effects of ethylene on Azospirillum brasilense strain Sp7 and to deliniate the signal transduction pathway involved in these responses. One main focus was to determine the role of the ethylene receptor, AzoEtr1, in these responses. Since this is a plant-associated bacterium and plants produce ethylene, we evaluated the role of this pathway in mediating the ability of A. brasilense to associate with plants. Overall design: Cells were grown in liquid minimal media for A. brasilense (MMAB) with sodium nitrate for 12h. They were then treated for 4h with 0.1 ppm ethylene or ethylene-free air (controls) prior to RNA extraction and analysis. Three replicates of each conditions were obtained. But, one air sample (Air Rep 3) did not cluster with the other 2 replicates in PCA analysis and was removed from further analysis.