TABLE 2

Phenotypes of Ptrp-syrA strains

StrainDescriptionMotilityaEPS-IbGrowth on TYSymbiosiscPtrp-exoR compatibled
Rm1021/pMB89WT; Ptrp-syrA+++++
Rm1021/pMB90WT; control plasmid++++
EC69/pMB89chvI K214T mutant; Ptrp-syrA+/−++++
EC69/pMB90chvI K214T mutant; control plasmid++/−
  • a Swimming motility assayed as described in Materials and Methods. Swim motility colony diameter of EC69 pMB89 was ∼55% of that of EC69 pMB90. −, nonmotile; +, motile.

  • b Brightness on LB agar plates containing 0.02% calcofluor white and exo gene expression in arrays. ++ indicates both increased brightness and exo gene expression compared to the wild type (+), and − indicates both decreased brightness and exo gene expression compared to the wild type.

  • c Medicago sativa and M. truncatula overall effectiveness of symbiosis based on the number of nodules and plant appearance. −, ineffective symbiosis; +, effective symbiosis.

  • d Ability to introduce the Ptrp-exoR plasmid (pDW83) into the strain. The empty vector (pMS03) was successfully used as a positive control for conjugations of pDW83 into S. meliloti strains containing pMB89 or pMB90. Rm1021/pMB89 and Rm1021/pDW83 and EC69/pMB89 and EC69/pDW83 strains were mucoid. −, not compatible; +, compatible.