Figure 2.

The mwp1 Phenotype in Vegetative Leaves.

(A) Wild-type leaves consist of three domains along the proximal/distal axis: sheath (sh), auricle (au), and blade (bl). The ligule (li) normally develops at the sheath-auricle boundary on the adaxial side (left) and is absent from the abaxial side (right).

(B) to (E) Different domains of the wild-type leaf are distinguishable based on epidermal characteristics.

(B) Adaxial blade, showing macrohairs.

(C) Abaxial blade, lacking macrohairs.

(D) Adaxial sheath, which is not hairy.

(E) Abaxial sheath, which is hairy.

(F) mwp1-R mutants have an ectopic ligule at the sheath-auricle boundary as well as adaxialized sectors (red arrow) that extend below the ligule and above the node, sometimes with development of large laminar flaps (black arrow). The horizontal line marks the position of the section shown in (G).

(G) Transverse section through a mwp1 mutant sheath, showing ectopic cell proliferation and extra vascular bundles lacking the abaxial hypodermal sclerenchyma.

(H) Transverse section through the wild-type sheath.

(I) Single flaps (white arrow) often develop at the sheath margins.

(J) Scanning electron micrograph of the margin region, including a nonhairy margin flap (left) that develops adjacent to normal-looking hairy sheath (right).

(K) Close-up view of the flap epidermis showing absence of hairs.

(L) Transverse section across the tapered sheath margin of a wild-type leaf.

(M) Close-up view of a wild-type vascular bundle, showing adaxial (ad) xylem and abaxial (ab) phloem.

(N) Transverse section through the margin region of a mwp1-R mutant leaf, showing the true margin (blunt) and the ectopic margin (tapered).

(O) to (Q) Close-up views of mwp1-R vascular bundles, with xylem at a peripheral location, as in (O) and (Q), or correctly oriented, as in (P).

Bars = 500 μm in (E), 1 mm in (J), and 200 μm in all others.