Figure 4.

SUF4 is expressed in developing FGs. A and B, pSUF4::SUF4-GUS activity is detected neither in the megaspore mother cell (mmc; A) nor in the tetrad of megaspores (B). C, SUF4-GUS is detected in developing ovules from stage 3-I on, initially in the nucleus of the functional megaspore forming the haploid FG. D and E, SUF4-GUS expression persists in the developing embryo sac. F, In the seven-celled embryo sac (stage 3-V), SUF4-GUS is detected in all seven nuclei. G, At stage 3-VI, SUF4-GUS is no longer expressed in the egg cell but only in the nuclei of the central cell and synergid cells. Ovule stages are according to Schneitz et al. (1995). ap, Antipodal cells; cc, central cell; ec, egg cell; fg, FG; ii, inner integument; oi, outer integument; syn, synergid cells. Bars = 20 µm