S., Melville, NY). β-glucuronidase expression by bacteria on LBMC plates was detected by streaking bacteria to plates that had been spread with

40 μL of X-gluc solution (100 mM 5-bromo-4-chloro-3-indolyl-beta-D-glucuronic acid, cyclohexylammonium salt solution in dimethylformamide). Table 3 Expression of β-glucuronidase (GUS) fusions ORF strain % of nodules with GUS expression Strength of nodule GUS expression Staining time Pattern of nodule GUS expression Free-living GUS expression N/A S. meliloti 1021 Selleckchem Fludarabine wild type (negative control) 0/39 = 0% − variable none − SMc00911 SMc00911.original 18/20 = 90% ++++ 1.5–3.75 hr whole nodule +   SMc00911.Xsd1 18/18 = 100% ++++ 1.5–3.75 hr whole nodule n.d.   SMc00911.original2 n.d. n.d. N/A N/A + SMb20360 SMb20360.original 8/13 = 62% ++ 3–5 hr invasion zone-fixation zone −   SMb20360.Xsd1

13/16 = 81% ++ 3–5 hr invasion zone-fixation zone − SMc00135 B104.3A 6/8 = 75% + 2–3 hr LY3039478 mouse invasion zone-interzone +   B104.4B 8/8 = 100% + 2–3 hr invasion zone-interzone ++   B104.2 C 6/8 = 75% ++ 2–3 hr invasion zone-interzone ++ SMc01562 A104U.original 7/8 = 88% + 4–6 hr interzone −   A104U.Xsd1 3/7 = 43% +/− 4–6 hr interzone-fixation zone n.d.   A104U.Xsd6 8/8 = 100% + 4–6 hr interzone-fixation zone n.d.   A104U.Xsd25 3/8 = 38% +/− 4–6 hr interzone-fixation zone n.d.   A104U.Xs100 4/9 = 44% + 4–6 hr fixation zone n.d. SMc01266 SMc01266.original 13/18 = 72% + 3 hr invasion zone-fixation zone +/−   SMc01266.Xsd1 13/18 = 72% ++ 3 hr invasion zone − SMc03964 SMc03964.original 8/15 = 53% ++ 3–5 hr interzone +/−   SMc03964.Xsd6 9/19 = 47% ++ 3–5 hr interzone-fixation zone − SMc01424-22 D104.2A 0/8 = 0% − 4–6 hr N/A +/−   D104.3B 7/8 = 88% ++ 4–6 hr invasion zone-interzone +/−   D104.1 C 6/8 = 75% + 4–6 hr invasion zone-fixation zone +/− SMa0044 SMa0044.104.1A 4/8 = 50% +/− 6–7 hr invasion zone-interzone Idoxuridine +++   SMa0044.104.1B 4/8 = 50% +/− 6–7 hr interzone

+++   SMa0044.104.4 C 4/8% 50% +/− 6–7 hr interzone +++ SMb20431 SMb20431.original 10/16 = 63% + 5–12 hr invasion zone-fixation zone −   SMb20431.Xsd1 11/15 = 73% + 5–12 hr interzone − SMc01986 C104.1A.Xsd1 0/6 = 0% − 24 hr N/A n.d.   C104.1A.original n.d. n.d. 24 hr n.d. +/−   C104.2B.Xsd100 2/18 = 11% +/− 24 hr fixation zone n.d. SMa1334 SMa1334.original 0/11 = 0% − 5–24 hr N/A −   SMa1334.Xsd1 0/13 = 0% − 5–24 hr N/A − Results Comparisons of Sinorhizobium meliloti open reading frames with those of other rhizobia and with non-nitrogen fixing α-proteobacteria Rhizobial functions required for symbiotic nitrogen fixation with legume plants have typically been discovered through the classical bacterial genetic technique of transposon mutagenesis, followed by screening mutants for loss of symbiotic function. We have used an alternative comparative genomics strategy to search for rhizobial genes involved in symbiosis.