Gene complementation
To generate target gene complementary strains, we cloned each intact target gene into the broad host range plasmid vectors pBBR1MCS5 (Kovachet al ., 1995), pSRKGm (Khan et al ., 2008) or pLAFR3 (Keenet al ., 1988), generating pCOK218 (pBBR1MCS5::crtEXYIBZ ), pCOK197 (pBBR1MCS5::PlaceanI ), pCOK199 (pBBR1MCS5::PlaceanR ), pCOK312 (pSRKGm::PlacrpoS ), pBS28 (pLAFR3::hfq , pLAFR3::arcZ ), or pOR78 (pBBR1MCS5:: PlacclpP ) which were transferred to the corresponding mutant strains by conjugation (Supplementary Table S1).