Fig. 4. Expression pattern of the HVE gene as uncovered by the P_ETA2-GUS transgene. (A) GUS staining of Col-0 seedlings carrying (right) or not (left) the P_ETA2-GUS transgene. All the remaining pictures (B-R) correspond to transgenic plants. (B) Roots; (C) a rosette, magnified in D; (E) cotyledon; (F) first, (G) third and (H) seventh vegetative leaves; (I) cauline leaf; (J) sepal; (K) petal and stamen; (L) inflorescence; (M) several immature flowers; and (N) a single mature flower. (O-Q) Details of the venation of a first leaf at several magnification levels; (R) a vein before xylem differentiation (red arrow) in a seventh leaf. Plant material was collected 10 (A,B), 21 (C-H,O-R) and 35 (I-N) days after sowing. Scale bars: 1 mm in A-I,N; 2 mm in L; 500 µm in J,K,O; 250 µm in M; 5 µm in P; 2.5 µm in R; 1.25 µm in Q.