Figure 5.

NTH20 Expression Analysis.

In situ hybridization of an NTH20 antisense probe in wild-type and antisense NSPHAN transgenics. Bars = 100 μm in (A) and (F), 80 μm in (B) and (C), 50 μm in (D), 60 μm in (E), and 2 cm in (G) and (H).

(A) NTH20 mRNA is detected in the peripheral zone (pz) of the shoot meristem where leaf primordia (lp) are initiated but absent in the central zone of the meristem (cz). v, vascular.

(B) and (C) NTH20 is not detectable in leaf primordia (B) in stages P2 to P5 but is present near the leaf/stem junction in P7 primordia (C) where axillary meristems (ax) are formed. mv, midvein.

(D) and (E) Ectopic expression of NTH20 is observed in adult antisense primordia, both in the midvein and in the surrounding rib cortex. lb, leaf blade; mv, midvein.

(F) Ectopic NTH20 is also observed in leaf primordia of juvenile antisense transgenics, particularly on the adaxial surface (ad) and in its normal location in vascular traces (v) in the adjoining stem. ab, abaxial.

(G) and (H) The curled lamina and ectopic blade phenotype in juvenile leaves of heterozygous transgenics (G) is strongly suppressed by application of GA as shown in (H). Arrows show vestigial ectopic blades on the midrib and remnants of disorganization at the leaf tip.