a, IRR phosphorylation sites affected by AtPep1 treatment. b, p35S:IRR-3xHA plants were treated with 1 μM solutions of AtPep1 for 0, 10, 20 and 30 min, or (c) 4 and 8 h. d, p35S:IRR-3xHA plants were treated with 0, 0.1, 0.5 and 1 μM solutions of AtPep1 for 30 min. IRR protein was subjected to immunoblot analysis with anti-phospho-Ser and anti-HA antibodies. Experiments in b–d were repeated three times independently, with similar results.