Fig. 2.

Gas exchange and guard cell reactive oxygen species production in response to blue light. (a) Stomatal conductance (g _s) and net photosynthetic rate (A) in response to blue light in intact leaves of the leptosporangiate fern Nephrolepis exaltata, the eusporangiate fern Angiopteris evecta and the angiosperm Arabidopsis thaliana. Six biological replicates were performed and a typical result is shown. (b) Half‐time for stomatal opening under blue light, measured as g _s in intact leaves, in the species from (b). For (a) and (b), measurement of g _s and A commenced in the dark, as the control, followed by 100 μmol m⁻² s⁻¹ blue light. Data are means ± SE (n = 3–6 biological replicates). *, P < 0.05; **, P < 0.01. (c, d) Confocal images (c) and fluorescent probe intensity (d) of blue‐light‐induced reactive oxygen species (ROS) in guard cells of the leptosporangiate fern N. exaltata, the eusporangiate fern A. evecta and the angiosperm A. thaliana. Scale bar in (c) is 10 μm. For (d), n = 4 biological replicates with 30–50 stomata; data are means ± SE.