Fig. 1. Expression of ACR4 during development. (A,C) Fluorescence images of two- to four-cell (A) and eight-cell (C) embryos (arrows). (B,D) In situ hybridisations of the same sections with ACR4 antisense probe. Expression is detected as light brown coloration in the eight-cell embryos but not in two- to four-cell embryos. (E-H) ACR4 expression in the L1 (outer) cell layer of developing embryo, inflorescence (im) and floral meristems (fm). In situ hybridisation (F) and confocal images (E,G,H) of H2B::YFP expression (green) in pACR4 transactivation lines. (I) In mature ovules expression is detected in the outer cell layer of the funiculus (f), the outer integument (oi) inner integument (ii) and endothelium (en). (J) In the root tip expression occurs in at least four columella (c) cells layers, the lateral root cap (LRC) and the quiescent centre (QC) but not in the epithelial cell file (e). (K) Expression in the root epithelial cell file (e) initiates as epithelial cells emerge from the LRC. c, cotyledon primordia; rp, embryonic root pole; sam, embryonic shoot apical meristem; fg, female gametophyte; m, micropyle. Scale bars: 25 µm except for K (10 µm).