Figure 7. The ethylene and H₂O₂-induced stomatal response pathway downstream of AHK5 involves ARR4 and ARR7. (A) Stomatal aperture in leaves of wild type (Col-0, WS), arr4, arr7 and ARR4^D95N (non-phosphorylatable ARR4 overexpressor) Arabidopsis plants. The leaves were exposed to 100 µM ethephon for 2h. Data are expressed as stomatal aperture response relative to mock-treated controls. Data are derived from measuring the apertures of at least 60 stomata from 3 independent experiments. * = Statistical difference (p-value ≤ 0.001 via Student’s t-test) compared with the wild type plants. (B) Stomatal aperture in leaves of wild type (Col-0, WS), arr4, arr7 and ARR4^D95N (non-phosphorylatable ARR4 overexpressor) Arabidopsis plants. The leaves were exposed to 100 µM H₂O₂ for 2h. Data are expressed as stomatal aperture response relative to mock-treated controls. Data are derived from measuring the apertures of at least 60 stomata from 3 independent experiments. * = Statistical difference (p-value ≤ 0.001 via Student’s t-test) compared with wild type plants.