TABLE 1.

Strains and plasmids used in this study

Strain or plasmidRelevant characteristic(s)Reference or source
Strains
    S. meliloti
        1021Wild type, Str29
        242Wild type, Str9
        Mf11021 furSm::Ω cassetteThis work
        Mf2242 furSm::Ω cassetteThis work
        1021(pShm)1021 containing plasmid pShmThis work
        242 (pShm)242 containing plasmid pShmThis work
        1021 (pMan)1021 containing plasmid pManThis work
        242 (pMan)242 containing plasmid pManThis work
        Mf1 (pShm)Mf1 containing plasmid pShmThis work
        Mf2 (pShm)Mf2 containing plasmid pShmThis work
        Mf1 (pMan)Mf1 containing plasmid pManThis work
        Mf2 (pMan)Mf2 containing plasmid pManThis work
        1021(pOT)1021 containing plasmid pOT1This work
        242(pOT)242 containing plasmid pOT1This work
        Mf1(pLAFur,pMan)Mf1 containing both plasmids pLAFur and pManThis work
    E. coli DH5αsupE44 ΔlacU16980lacZΔM15)hsdR17 recA1 gyrA96 thi-1 relA115
Plasmids
    pBluescriptSK (pBSK)Cloning vector, AprStratagene
    pΩ45Plasmid containing Ω Spr Str cassette8
    pWS233Suicide vector in rhizobia, Gmr41
    pOT1Wide-host-range gfp-UV promoter-probe plasmid, Gmr, derivative of pBBR11
    pOT2Wide-host-range gfp-UV promoter-probe plasmid, Gmr, derivative of pBBR11
    pRK2013Helper plasmid, Kmr10
    pFurSm1.25-kb PCR fragment carrying the furSm gene and flanking regions cloned in pBSKThis work
    pBSKfurSmΩ0.8-kb furSm ends and flanking regions carrying an Ω cassette in place of furSm gene cloned in pBSKThis work
    pWSfurSmΩpWS233 carrying the 0.8-kb fragment containing an Ω cassette in place of fursmThis work
    pShmRpBSK with a 2.8-kb PCR fragment containing shmR, its presumptive promoter, and flanking regionsThis work
    pShmpOT1 with a 650-bp HindIII, SalI fragment containing the presumptive shmR promoter, GmrThis work
    pManpOT2 with a 750-bp KpnI, PstI fragment containing the presumptive mntA promoter, GmrThis work
    pLAFR3Low-copy-number, broad-host-range cosmid derivative of pRK290 (IncP1) PLAFR3 containing furSm and its presumptive promoter42
    pLAFurThis work