Figure 2.

Light exposure of dark-grown seedlings triggers a rapid PIN1 polarization at the leaf primordia and the establishment of localized auxin maxima. A, PIN1 immunofluorescence localization in the first two leaf primordia of wild-type seedlings: PIN1 (green) and 4′,6-diamino-2-phenylindole (DAPI; blue). Seedlings were germinated in the dark for 3 d, then examined immediately or after exposure to continuous white light for the times indicated (in hours). B, Enlargements of a primordium tip from the PIN1 localization images in A after 0, 2, and 24 h. C, DR5:GUS reporter activity of seedlings in the dark and exposed to white light for 24 h. Bars = 10 µm (A), 5 µm (B), and 50 µm (C).