BZR1 activity blocks RSA modulation in response to Pi deprivation. A, Total number of LRs in the wild type and bzr1-D on days 11 and 14 after germination when grown in the presence or absence of Pi (1 μm). B, LR density in these same lines. Note the high versus low LR density in the wild type and bzr1-D, respectively, in Pi deprivation conditions. Error bars represent se. **, P < 0.01 with two-tailed Student's t test. ***, P < 0.001 with two-tailed Student's t test. DAG, Days after germination.