Figure 4

Fluorescent dots in nuclei of guard cells. Images from a leaf of a plant homozygous for the 112 tagged locus. The gene encoding the EGFP-LacI fusion protein is under the control of the GC1 (guard cell) promoter. In the low magnification images (A, B), the GFP2 filter was used (at the excitation wavelength for GFP, chlorophyll has red auto-fluorescence using this filter). Many paired green dots, corresponding to guard cell nuclei, are visible in A (enlargement of boxed region shown in B). In the high magnification images (C, D), a YFP filter was used to see fluorescent dots (this reduces chlorophyll auto-fluorescence); D is the superimposition of the light microscopic image. Two fluorescent dots corresponding to the tagged sites are clearly visible above low background fluorescence in both diploid guard cell nuclei. The bars indicate 250 μm (A), 100 μm (B), and 5 μm (C and D).