Skip to main content
. 2021 Oct 13;10:e70934. doi: 10.7554/eLife.70934

Figure 3. WUS-dependent repression of CLE40 expression in the shoot meristem.

(A) Maximum intensity projection (MIP) of CLE40 expression (CLE40:Venus-H2B//Col-0) at 5 weeks after germination (WAG), (A’) Longitudinal optical section through the centre of the inflorescence meristem (IFM) (indicated by orange line in A) reveals no CLE40 expression in the central zone (CZ) and the centre of the meristem. Cells in the L2 layer also show less CLE40 expression. High CLE40 expression is found in the peripheral zone (PZ) (N = 23). (B) MIP of CLE40 expression in a clv3-9 mutant (CLE40:Venus-H2B//clv3-9) shows expression only in the PZ of the meristem, in flower meristems (FMs) and in sepals (N = 6). (B’) Longitudinal optical section through the IFM depicts no CLE40 expression at the tip and the centre of the meristem. CLE40 expression is only detected in cells at the flanks of the IFM and in sepals. (C) Arabidopsis seedling at 10 days after germination (DAG). (D) Seedling expressing WUS from the CLV3 promoter, 10 DAG. (D’) Magnification of seedling in (D). The meristem fasciates without forming flowers. (E) L1 projection, vegetative seedling with CLE40 expression in the PZ and leaf primordia starting from LP4, at 10 DAG (N = 5). (E’) Longitudinal section of (E) with CLE40 expression primordia and rib meristem or periphery. (F) MIP of fasciated meristem as in (D). CLE40 expression can only be found in the cotyledons (C1 and C2) next to the meristem (N = 5). (F’) Longitudinal optical section shows CLE40 expression only in the epidermis of cotyledons. (G, G’) MIP (G) and longitudinal optical section (G’) of CLE40 expression (CLE40:Venus-H2B//Ler) in a wild- type (Landsberg erecta [L.er]) background at 5 WAG shows no signal in the CZ or OC. CLE40 is confined to the PZ and the centre of older flower primordia, and to sepals (N = 8). (H, H’) MIP of CLE40 in a wus-7 background shows expression through the entire IFM and in the centre of flower primordia. The longitudinal optical section (H’) reveals that CLE40 is also expressed in the CZ as well as in the OC of the IFM (N = 12). Dashed orange lines indicate the planes of longitudinal sections, dashed red line in (A), (B), (E) and (F) marks the IFM area, the dashed pink line in (A) and (B) marks the sepals, the dashed rose line in (A) and (B) marks the FMs, the dashed white line in (E’) marks the CZ. Scale bars: 50 µm (A, B, G, H), 20 µm (A’, B’, E, E’, F, F’, G’, H’), 1 mm (C, D), 500 µm (D’). PI: propidium iodide; L1: layer 1 projection; C: cotyledon; LP: leaf primordium.

Figure 3.

Figure 3—figure supplement 1. CLE40 expression is lacking in the central zone (CZ) and organizing centre (OC).

Figure 3—figure supplement 1.

(A) Maximum intensity projection (MIP) of CLV3 and WUS expression (CLV3:NLS-mCherry;WUS:NLS-GFP//clv3-9) in a clv3-9 mutant inflorescence meristem (IFM) (N = 5). CLV3 expression is detected at the tip of the meristem, while WUS expression is predominantly found in young primordia surrounding the meristem. (A’) Longitudinal optical section through the IFM shows an extended expression domain of CLV3 in the CZ and WUS-expressing cells in OC of the IFM. (B) MIP of a clv3-9 mutant IFM expressing CLE40:Venus-H2B. CLE40 is expressed in the peripheral zone (PZ) of the IFM, in flower primordia and in mature sepals (N = 6). (B’) Longitudinal optical section through the IFM shows CLE40 expression in the outer layers of the PZ while it is lacking in the CZ and OC, where CLV3 and WUS are expressed. Dashed orange line indicates the planes of longitudinal optical sections; Scale bars: 50 µm (A, B), 10 µm (A’, B’). PI: propidium iodide.
Figure 3—figure supplement 2. CLE40 expression is extended in wus-7 mutants.

Figure 3—figure supplement 2.

(A) Landsberg erecta (L.er.) wild-type plant at 5 weeks after germination (WAG) shows normal plant growth, while wus-7 mutants at 5 WAG are delayed in their development (dashed white line). (B) wus-7 mutant at 8 WAG. wus-7 mutants develop inflorescence meristems (IFMs) but give rise to sterile flowers that lack inner organs. (C, D) Maximum intensity projection (MIP) of wus-7 IFMs at 5 WAG expressing CLE40:Venus-H2B. CLE40 expression is detected through the entire meristem and in the centre of primordia (N = 12). (C’, D’) Longitudinal optical sections through the meristem show CLE40 expression in an extended pattern in the peripheral zone (PZ) and the organizing centre (OC). Dashed white line in (A) encloses homozygous wus-7 mutants, dashed orange line indicates the planes of longitudinal optical sections; Scale bars: 20 mm (A, B), 20 µm (C–D’).