Figure 4.

Expression of Medsa;cycA2;2 is induced during nodule initiation, and the presence of the CycA2 protein correlates with cell proliferation. A, RT-PCR analysis of cycA2;2 gene activation in the nodulation-competent root zone of alfalfa after S. meliloti or Nod factor application. B, Western-blot analysis of CycA2 protein during nodule development in alfalfa roots. Protein extracts were made from Rm41-inoculated root segments at the indicated time points and from the apical and basal parts of 3-week-old nitrogen-fixing nodules.