Figure 1. The nin mutant is defective in bacterial differentiation in nodules. (A) WT nodule is pink because it contains leghemoglobin. (B) In contrast, nin mutant forms white nodules. (C) Differentiated elongated bacteria (green) in WT nodules (C) and (D) non-differentiated small bacteria in mutant nodule. C, D are confocal images. Rhizobia expressing GFP were used for inoculation of roots.