Figure 5.

UV-B activation of MPK3 and MPK6 depends on H₂O₂ production but not NO production. A, Leaves of wild-type (WT) Col-0 and mutants AtrbohD, AtrbohF, and AtrbohD/F were exposed to light alone or with 0.5 W m⁻² UV-B for 2 h. B, Leaves of wild-type Col-0 and mutant mpk6-4 were incubated in MES buffer containing 100 µm H₂O₂ for the indicated times. C, Leaves of wild-type Col-0 and Landsberg erecta (Ler) and mutants nia1-2 (nia1), nia2-1 (nia2), and nia1-1/nia2-5 (nia1/2) were exposed to light alone or with 0.5 W m⁻² UV-B for 2 h. After treatments, total proteins were extracted from the treated leaves, and immunoblot analysis was performed with anti-phospho-p44/42 MPK and anti-actin (loading control) antibodies. The data shown are representative of up to three independent experiments.