Figure 3.

Juvenile Antisense Phenotype.

In the juvenile vegetative phase, antisense NSPHAN transgenics produce leaves with normal adaxial/abaxial polarity but with a specific disruption in the adaxial domain, leading to formation of ectopic leaf blades on the lateral flanks of vascular ribs. Bars = 40 μm in (B), 20 μm in (C), 100 μm in (D), and 80 μm in (E) to (I).

(A) Ectopic leaf blades (EB) emerge at the junction between the primary blade (PB) and the midrib and show a fixed polarity, the adaxial surface facing away from the rib.

(B) Transverse sections of ectopic blades show differentiation of palisade (ectopic blade palisade, ebp) and lateral veins (ectopic blade vein, ebv).

(C) and (D) Scanning electron micrograph of transgenic leaf primordia in (C) shows a flattened adaxial surface at the P2 stage, and longitudinal sections in (D) show normal adaxial/abaxial differentiation, indicating that leaf polarity is normal in the absence of NSPHAN. ad, adaxial; abr, abaxial rib; adb, adaxial blade; mv, midvein.

(E) The primary disruption in transgenic leaves is abnormal proliferation and lack of palisade differentiation in the upper mesophyll beginning at stage P5, which forms a continuous pavement over the midvein (mv) and lateral veins (lv). um, upper mesophyll.

(F) and (G) Corresponding wild-type leaves have palisade initials at this stage in the upper mesophyll (um), which form a single cell layer over lateral veins (lv). mv, midvein.

(H) Where the abnormal upper mesophyll (um) of transgenics abuts adaxial cortex (adc) over the midvein (mv), periclinal cell divisions produce ectopic blade (eb) primordia.

(I) Vascularized blade primordia (ectopic blade vein, ebv) emerge vertically on either side of the midrib, with an adaxial surface (ectopic blade adaxial, ebad) that is contiguous with the upper mesophyll of the primary blade (umpb), thus facing away from the rib.