Fig. 2

Timing and specificity of a putative SlINO promoter directing expression of an SlINO-GFP transgene. Confocal images (a-c, g-i) overlaid on corresponding DIC images (d-f, k-l) of tomato ovules. Control ovule with no transgene is shown in i, l. In this ovule the visible fluorescent dots are likely to be auto-fluorescence from plastids. All other images are from plants containing a P-SlINO::SlINO-GFP transgene. No GFP signal is present in stage 8 ovule primordia prior to integument initiation (a, d) or at stage 10, when asymmetric thickening of the primordium (arrow) signals emergence of the integument (b, e). GFP localized in the outermost cell layer is visible in the newly emerged integument primordium in stage 11 (c, f). This pattern continues as the integument grows asymmetrically to cover the nucellus in stage 13 (g, j) and form the micropyle in the mature ovule at stage 18 (h, k). Expression is low or absent in the cells at the distal tip of the integument (c, g, h).op, ovule primordium; f, funiculus; i, integument; n, nucellus; o, ovule; p, placenta; arrowhead, micropyle. Scale bars are 20 μm