Fig. 1. HY5 is required for the light regulation of stomatal development.

a–c Changes in stomatal production in response to light intensities in WT, hy5-215, and HY5-OX (overexpression line of HY5). Arabidopsis seedlings were grown for 10 days at 22 °C under three distinct light intensities (40, 80, and 160 µmol m⁻² s⁻¹). Representative images (a), stomatal densities (b), and stomatal indices (c; see text) of the abaxial cotyledons are shown. Stomata are pseudo-colored in green (a). Scale bar, 80 μm. d, e Seedlings of the above genotypes (a) were grown for 3 days to capture the early cell types of the stomatal lineage under the three light intensities (a). Representative confocal images (d) and the percentage of these early cell types, which include meristemoids, guard mother cells (GMCs) and stomatal lineage ground cells (SLGCs) (e; see text and “Methods”) of the abaxial cotyledons are shown. Scale bar, 40 μm. b, c, e Values are mean + /− SEM, n = 10 independent cotyledons. Two-way ANOVA with Tukey’s multiple comparisons test, P < 0.05.