Fig. 4

Conservation of INO promoter shown by activity of P-SlINO in Arabidopsis (Ler), assayed using the GUS reporter. P-SlINO::GUS transgene activity (d-g) compared with P-AtINO::GUS transgene activity in (e-h). Early ovules (a, e) show no GUS activity in the emerging outer integument. Expression of the reporter in the outer integument is visible in ovules at stage 2-IV [63] but P-SlINO expression (b) is less extensive than P-AtINO at the same stage (f). This trend continues as the integuments extend towards the nucellus at stage 3-I (c, g). Finally, when the mature shape of the ovule is achieved at stage 4-I the pattern of GUS activity in d and h are similar though expression directed by P-AtINO (h) is concentrated toward the basal end of the integument as previously noted [5] while expression directed by P-SlINO is concentrated more toward the distal end of the integument. o: ovule; p: placenta; mp: micropyle; c: carpel wall; n: nucellus; ii: inner integument; oi: outer integument. Scale bar in h represents 25 μm in a-c, e-g; 50 μm in d, h