Figure 4.

AnnAt1 expression. A, Early expression in the epidermis in the zone of elongation in a root (r) tip, and in the root cap (arrow) of the germinating seedling; cotyledon (c), hypocotyl (h), and seedcoat (sc). B, Later expression includes internal cells of the root, and hypocotyl (h) epidermal cells. C, Expression in the seedling hypocotyl (h) occurs in the epidermis and vascular tissue. A small arrow shows the hypocotyl-root junction, and the large arrow indicates the root tip of another seedling. D, Cross section of a hypocotyl showing staining in the epidermis and vascular tissue. E, Root from a germinating seedling showing expression throughout the root base, including the hair cells, and excluded from the center of the root tip (arrow). F, Close-up of a root tip showing expression restricted to the epidermis of the root tip and outer rootcap cells. G, Longitudinal section through d 7 seedling showing expression in the trichomes (arrows), the hypocotyl vasculature (hv), and cotyledon (c) vasculature; lp, leaf primordia. H, Longitudinal section through d 14 plant showing expression in trichomes (arrow), pith meristem (p), leaf bases (lb), hypocotyl vasculature (hv), and leaf vascular tissue (vt). I, Close-up of d 14 plant showing vascular expression occurs in the phloem (ph) and not the xylem (x); floral meristem (f), shoot meristem (s), and pith meristem (p). J, Close-up of a cross section through a leaf base showing expression in the phloem (ph) and not the xylem (x). Scale bar lower left: A, 60 μm; B, 75 μm; C and E, 500 μm; D, 140 μm; F, 130 μm; G and H, 400 μm; I, 180 μm; and J, 50 μm.