RNAseq of Sinorhizobium meliloti 1021 treated with the chemically synthesized peptide DgDef1 delta SP delta CTPP (representing a truncated variant of the Defensin-like peptide DgDef1 from the actinorhizal plant Datisca glomerata) against an untreated control

Plant-derived nodule-specific Cys-rich peptides (NCRs) play essential roles towards microsymbionts control. To pinpoint whether DgDef1 — a nodule-specific defensin from the actinorhizal plant Datisca glomerata — fulfills similar functions, the peptide was characterized. DgDef1 affects growth of several bacteria including Sinorhizobium meliloti. In this experiment, it was analyzed if DgDef1 without its CTPP domain (DgDef1delta SP delta CTPP) triggers a cellular response in S. meliloti. The S. meliloti strain Rm1021 was challenged in 10 mL TY medium (OD600 = 0.5) with 25 µg/mL of DgDef1 delta SP delta CTPP at 30°C, 150 rpm for 1h. The negative control was treated with acetonitrile:water (1:3) instead of DgDef1 delta SP delta CTPP. Assays were performed in four replicates. RNA was isolated and material from biological replicates were combined in equal amounts. This resulted in two RNA pools representing DgDef1 treated and untreated Rm1021 cells. The pooled RNAs were used for RNAseq in order to identify differentially expressed genes.