2′, 3′cAMP effect on Clr-DNA binding and smc02178 expression. (A, B) EMSA assays showing Clr binding to 28-mers oligomers including the wt Clr-box (A) or a mutated version (B), as in Figure 5. Assays were performed in the presence of 1.75 nM oligomers, 200 μM 3′, 5′cAMP and/or 200 μM 2′, 3′cAMP, and 69 μM Clr (for details, see methods). (C) smc02178-lacZ expression was monitored ex planta in S. meliloti 1021 WT and a ΔSpdA strain after addition of M. sativa shoots extract (MS) and/or 7.5 mM 2′, 3′cAMP. *p < 0.03 compared to the wild type.