Confocal Characterisation. Enhancer trap lines found to express GFP when examined under fluorescence microscopy were further characterised using confocal microscopy. (A, B & C) Confocal images along the primary root of one line. (A) At the root apex GFP expression is seen in the columella and within files of cells in the lateral root cap. (A) Weak expression within the vascular cylinder begins in the elongation zone of the root and (B & C) increases in intensity in more mature parts of the root. (D & E) Unfixed vibratome sections of the inflorescence stem of two of the lines showing (D) sporadic GFP expression in the cortex, phloem, protoxylem and pith., and (E) intermittent expression confined to a few cells in both the xylem and phloem poles. (F, G & H) GFP expression in the young leaves of three lines. (F) Patchy epidermal expression is concentrated at the leaf margin and petiole, and within the leaf GFP is seen in the vasculature and scattered mesophyll cells. (G) GFP expression in the young leaves and primordia of this line is concentrated along the midline in epidermal and underlying mesophyll cells. (H) Guard cells in all aerial tissues of this line express GFP. (I) Guard cell GFP expression. Expression is first seen in the bent cotyledon stage embryo.
