FIGURE 1.

Nodulation specificity associated with Sinorhizobium fredii USDA193 in soybean. The bacterial strain formed nitrogen-fixing nodules on Peking (A) but only small nodule primordia on Williams 82, as indicated by the arrowheads (B). In the compatible Peking/USDA193 interaction, nodules developed normally and contained bacteria (C), whereas in the incompatible interaction between Williams 82 and USDA193, the nodule primordia did not contain bacteria (D). Bars = 100 μm. However, USDA193 induced root hair curling (indicated by arrowheads) on both Peking (E) and Williams 82 (F). Photographs were taken 5 days post inoculation. Bars = 100 μm.