TABLE 1.

Bacterial strains and plasmids

Strain or plasmidCharacteristicsReference
Sinorhizobium meliloti strains
    Rm1021Spontaneous mutant of wild-type strain RU47, Smr35
    Rm1021-TR2Rm1021 derivative, ΔrirAThis study
    Rm1021-TR2-3Rm1021 derivative, ΔrirA ΔrhrAThis study
Escherichia coli strains
    DH5αMCRF endA1 supE44 thi-1 λ recA1 gyrA96 relA1 deoR Δ(lacZYA-argF)U169 φ80dlacZΔM15 mcrA Δ(mrr hsdRMS mcrBC)20
    S17-1E. coli 294::[RP4-2(Tc::Mu)(Km::Tn7)] pro res ΔrecA Tpr57
Plasmid
    pK18mobsacBpUC18 derivative, sacB lacZα Kmr, mobilizable53