Characteristics of S. meliloti transcripts. (a) Nucleotide composition for the first 3 nt of mRNAs Positions +1, +2, and +3 are indicated, of which +1 is the TSS. (b) Distance of TSS to start codons. In orange: TSS of leaderless transcripts (lmTSS); purple: TSS located close to the start codon that were classified as putative TSS of sense sRNAs (seTSS); green: TSS of mRNAs, including cis-encoded mRNA leader sequences of blue: TSS of putative mRNAs (pmTSS). (c) (ia) Transcription units identified by both the TSS-specific RNAseq and the small RNA-specific RNAseq approach (applying stringent  and relaxed thresholds). (ib) mRNA leader sequence (SmelCR345), (ii) sRNA (SmelBR028), (iii) leaderless transcript (SmelAR015) and (iv) asRNA (SmelBR068). TSS are indicated by blue triangles.