Figure 3.

Positive complementation of the nodulation phenotype on the transgenic hairy roots of the lin-1 mutants. A, Detection of the transgenic roots and nodules by GFP fluorescence. Hairy roots were induced without antibiotic selection, allowing the emergence of both transgenic (bright green fluorescent roots) and nontransgenic (yellowish) roots. B, Mature nodule on the transgenic root of the lin-1 mutant occupied by S. meliloti strain 1021 carrying a hemA promoter:lacZ fusion, stained for β-galactosidase activity. Bacteria visualized in the nodule revealed that wild-type nodule development and an invasion process occurred in the complemented roots. C, Nodule primordia on control nontransgenic roots of the lin-1 mutant inoculated with the same bacteria showed the mutant phenotype with the nodule primordia and arrested infections in the root hairs. Bars = 200 μm (B) and 10 μm (C).