Total RNA was extracted by using TRI Reagent® (Invitrogen) followed by Turbo DNase treatment (Ambion) and RNA clean-up with RNeasy Mini Kit (Qiagen), according to manufacturers´ instructions. The RNA concentration was determined spectrophotometrically and RNA degradation and contamination was assessed by electrophoresis on 2% (w/vol) agarose gels. The synthesis of cDNA was performed using random hexamers (GE Healthcare) and SuperScript II reverse transcriptase (Invitrogen) in a 25 µl reaction volume with 1 µg of total RNA and incubation at 42 ºC for 2 h. RT-qPCRs were performed as described previously  using primers described in supplementary Table S2. RNA sequencing was performed at Novogene Company Limited (United Kingdom) using samples from the wild-type D. dadantii 3937 and the ∆iaaM-km3 mutant grown in minimal medium supplemented with 0.25 mg/mL L-tryptophan (IAA precursor) and harvested at the early stationary phase of growth. Before sequencing, RNA integrity and quantification were assessed using the RNA Nano 6000 Assay Kit of the Bioanalyzer 2100 system (Agilent Technologies, CA, USA). One microgram of total RNA per sample (three biological replicates per strain) was used to construct the sequencing libraries. These libraries were generated by using NEBNext® Ultra™ Directional RNA Library Prep Kit for Illumina® (New England Biolabs; #E7530), following the manufacturer's recommendations. Prior to library construction, ribosomal RNA was depleted with Illumina Ribo-Zero Plus rRNA Depletion Kit (Illumina; Ref. 20037135), according to the manufacturer's instructions. The resulting libraries were quantified by quantitative PCR and the inserts were measured using a LabChip GX instrument, using the LabChip NGS 3K reagent kit (PerkinElmer; CLS960013). Libraries were sequenced using the NovaSeq 6000 Illumina platform and paired-end reads were generated.