Figure 2. Quantification of the effect of L-buthionine-(S,R)-sulfoximine (BSO) on root penetration in pct1-2 seedlings. Note that simultaneous application of BSO along with 2 μL L−1 1-MCP inhibits DR5::GUS expression in the root tips (A) and root penetration (B) of pct1-2 seedlings. Seedlings were grown on Soilrite moistened with 0.5 mM BSO in the presence or absence of 1-MCP. The control seedlings were grown on Soilrite moistened with water. The asterisk (*) indicates a statistically significant difference in response to treatment (p < 0.005 with n = 15–20 per group).