Fig 1.
Plant and leaf structures of Egeria densa.
(A) Plant stature. (B) Three cell types in the mature leaf epidermis. Epidermal cells (arrowheads), idioblasts (arrows) and a marginal prickle-hair or tooth cell (double arrowhead) are represented. Note that the top surfaces of the projected idioblasts are in focus in this image. (C) Cross-section of the central zone of the mature leaf. The adaxial and abaxial sides of the leaf and the midrib are indicated. Inset represents magnification of the boxed area and shows an idioblast (arrow). (D) Bright-field (BF) and ultraviolet (UV)-induced fluorescence images of the leaf epidermis (taken using 10× objective). (E) Fluorescence image of the UV-irradiated leaf epidermis (taken using 4× objective). Scale bars: 5 mm (A); 50 μm (B–D); 200 μm (E).
Fig 2.
UV-induced autofluorescence from idioblasts in mature and late expanding leaves.
(A–D) Bright-field or fluorescent images of idioblasts in mature (A, B) and late-developing (C, D) leaves. For fluorescence microscopy, cells were excited with UV (330–385 nm) and observed at >420 nm (A–D), 417–477 nm, 467–499 nm, >510 nm, 518–572 nm or >575 nm (B). Scale bars: 50 μm.
Fig 3.
Orientation and arrangement of idioblasts along the leaf proximal-distal axis.
Fluorescence images of idioblasts on UV-irradiated mature leaves are shown. (A) Singlet cell. (B) Doublet. (C) Side-by-side doublet along the left—right axis. (D) Triplet. (E) Quadruplet. (F) Quintuplet. (G) Sextuplet. (H) Septuplet. (I) Octuplet. (J) Nonuplet. Scale bars: 50 μm.
Fig 4.
Distribution patterns of idioblast clusters on the adaxial and abaxial surfaces of leaves.
(A) Fluorescence images of the adaxial and abaxial surfaces of half-leaves under UV excitation. Scale bar: 1 mm. (B) Schematic of the spatial distribution of singlet (gray), doublet (green), triplet (red), and quadruplet and more (orange) idioblasts across the half-leaves. (C) Frequency of idioblast clusters on the whole adaxial and abaxial surfaces of leaves. Data collected from 18 leaves for the adaxial (top) or 19 leaves for the abaxial (bottom) surface are shown. (D, E) Frequency of idioblast clusters on the whole adaxial and abaxial surfaces of leaves. Data from individual leaves for the adaxial (D) and the abaxial (E) surfaces are shown.
Table 1.
Quantitative measurements of idioblast clusters on adaxial and abaxial surfaces of E. densa leaves.
Fig 5.
Relationship between the leaf surface area and the number of idioblast clusters or cells.
(A) Idioblast clusters. (B) Idioblast cells. Data from 18 leaves for the adaxial (open symbols) or 19 leaves for the abaxial (filled symbols) surfaces are plotted.
Fig 6.
Consensus areas of idioblast formation on E. densa leaves.
(A, B) The apical (A) and basal (B) leaf zones defined in this study. Double arrowheads represent marginal tooth cells marking the boundaries between the central zone and the apical or basal zone. (C, D) Three schematics of idioblast cluster distributions on the adaxial (C) or abaxial (D) side of mature leaves. Color-dot annotation as in Fig. 4. (E, F) Schematic representations of areas of maximal (light-colored) and minimal (dense-colored) idioblast formation on the adaxial (E) and abaxial (F) surfaces of leaves. White areas represent a complete absence of idioblasts. Scale bars: 500 μm (A, B); 2 mm (C, D).
Table 2.
Distribution of idioblast clusters along the proximal—distal axis of E. densa leaves.
Fig 7.
Presence and mobility of boundaries defining areas of idioblast formation on both leaf surfaces.
(A) Schematics of adaxial (cyan dots in the colored areas) and abaxial (color annotations as in Fig. 4) idioblast clusters in three individual, whole leaves. (B–D) Fluorescence images of the apical (B), central (C), and basal (D) leaf zones under UV excitation. Scale bars: 2 mm (A); 200 μm (B–D).
Fig 8.
Tracking idioblast differentiation in young expanding leaves.
(A) Bright-field (BF) and UV-induced fluorescence images of an expanding leaf 1.2 mm in length. (B–G) Bright-field (BF) and UV-induced fluorescence images of idioblasts and surrounding epidermal cells with (B–D) or without (E–G) positive chlorophyll signals. (H–K) Neutral red-staining images of mature (H, I) and expanding (J, K) leaves. Scale bars: 100 μm (A); 50 μm (B–G); 20 μm (H–K).