Figure 8.

Shoot tissue showing effects of the CYCD2 transgene on cell proliferation and expansion, but little effect on leaf size, in wild-type (wt) and transgenic (gD6) lines. A and B, Shoot tissue at 22 d showing similar shoot development and similar final size of fully expanded first leaves (arrowheads). C and D, Fully expanded first leaves in scanning electron microscopy showing similar morphology and trichome development. E and F, Proliferating protodermal cells in the first leaf at 6 d with new cross walls visible and smaller transgenic cell size from earlier entry into division relative to growth. G and H, Proliferating mesophyll cells in the first leaf at 6 d showing recent divisions and in the transgenic smaller cylindrical palisade cells also retarded expansion of spongy mesophyll and leaf thickness. I and J, Fully expanded epidermis of first leaves at 22 d showing smaller size of transgenic nonstomatal cells and higher stomatal number per unit area. K and L, Fully expanded leaf tissue of first leaves showing in transgenic, smaller final size of palisade cells and greater contribution of spongy mesophyll to normal leaf thickness. Bar = 4 mm (A and B); 1 mm (C and D); 10 μm (E and F); 30 μm (G and H); 100 μm (I–L).