Transcriptomic Response of the Diazotrophic Bacteria Strain PAL5 to Iron Limitation and Characterization of the Regulatory Network.

has been the focus of several studies aiming to understand the mechanisms behind this endophytic diazotrophic bacterium. The present study is the first global analysis of the early transcriptional response of exponentially growing to iron, an essential cofactor for many enzymes involved in various metabolic pathways. RNA-seq, targeted gene mutagenesis and computational motif discovery tools were used to define the regulon. The data analysis showed that genes encoding functions related to iron homeostasis were significantly upregulated in response to iron limitations. Certain genes involved in secondary metabolism were overexpressed under iron-limited conditions. In contrast, it was observed that the expression of genes involved in Fe-S cluster biosynthesis, flagellar biosynthesis and type IV secretion systems were downregulated in an iron-depleted culture medium. Our results support a model that controls transcription in by function. The protein was able to complement an mutant. These results provide new insights into the effects of iron on the metabolism of , as well as demonstrate the essentiality of this micronutrient for the main characteristics of plant growth promotion by .