Fig 3.

A. β-galactosidase activity of R. tropici CIAT 899 carrying plasmid pMP240 under different mannitol concentrations (55–500 mM). B. β-galactosidase activity of R. tropici CIAT 899 and its nodD mutant derivative strains carrying plasmid pMP240 under 400 mM mannitol. Black, blue, red, green, gray and white bars represent β-galactosidase activity levels of the wild-type, nodD1 mutant, nodD2 mutant, nodD3 mutant, nodD4 mutant and nodD5 mutant strains, respectively. Expression data were individually compared with the expression without inducing molecules of the wild-type strain using the Mann-Whitney non-parametrical test. The asterisks (*) indicate a significant difference at the level α = 5%. C. Thin-layer chromatography analysis of Nod factors produced by R. tropici CIAT 899 and the nodD2 mutant grown under control and 400 mM mannitol conditions. D. Biological activity assay of the NF purified from the wild-type and the nodD2 mutant strain applied to common bean roots. The number of nodule primordia was individually compared to those primordia formed by the wild-type strain using the Mann-Whitney non-parametrical test. The asterisks (*) indicate a significant difference at the level α = 5%.