FIG 4.

Nodules from soybean inoculated with B. diazoefficiens USDA 110 in the absence (A to D) or the presence (E to J) of 10 mM NH₄NO₃. The wild type (A, C, E, and G) and its rsh mutant derivative (B, D, F, and H to J) are compared. Entire nodules were viewed under a stereomicroscope (A, B, E, and F). Ultrathin cuts from these nodules were observed with a transmission electron microscope (C, D, and G to J). To confirm the role of rsh in the phenotypes observed, the rsh mutant was complemented with the wild-type rsh complete gene carried in the replicative vector pFAJ1708 (I) or the empty vector (J). The micrograph set is representative of results from three independent experiments.