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First published online February 18, 2004
doi: 10.1242/10.1242/dev.00991

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The Arabidopsis JAGGED gene encodes a zinc finger protein that promotes leaf tissue development

Division of Biology 156-29, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA

View larger version (106K): [in a new window]   Fig. 1. Morphology of jag floral and vegetative organs. (A) Wild-type Landsberg erecta flower. (B,C) jag-3 flower with narrow petals curling towards adaxial surface. Sepal with serrations at the distal tip is marked with an asterisk. (D) jag-2 flower. (E) SEM of jag-3 flower with a narrow sepal (arrowhead). (F) jag-3 abaxial petal with buckled margins. (G) jag-3 stamens fused along filament margins. (H) jag-3 gynoecium abnormally fused at the stigma. (I) Wild-type inflorescence with sepals enclosing floral buds. (J) jag-3 inflorescence with gynoecium protruding from floral bud (arrowhead). A wide medial sepal is present on the same flower (white arrow). A black arrow indicates a stage 7 flower with carpels protruding. (K) jag-3 early floral primordia with an extra sepal primordium initiated (arrow). (L) Petal primordium (p) from stage 9 jag-3 flower. (M) Petal primordium (p) from stage 10 jag-3 flower. (N) Wild-type 7-day post germination seedling. (O) jag-3 seedling with altered cotyledon shape. (P) Fifth rosette leaf from wild-type (left) or jag-3 (right) that has serrated margins. Scale bar: 100 µm (E-K,M); 10 µm (L); 1 mm (N-P).

View larger version (217K): [in a new window]   Fig. 2. SEM analysis of wild-type and jag mutant petals. (A,D) Distal, (B,E) middle and (C,F) proximal regions of abaxial epidermal surface. (A-C) Wild-type with (A) round epidermal cells (arrow), (B) a mixture of round (arrow) and elongated cells (arrowhead) and (C) elongated cobblestone-shaped cells (D-F) jag-2 mutant with (D) elongated cobblestone-shaped cells, (E) elongated cells (note the fewer number of cells along proximal-distal axis than in wild type) and (F) elongated cobblestone-shaped cells. (G,H,I) The distal regions of the abaxial petal epidermis in wild-type, jag-3 and jag-2, respectively, showing the allelic differences in phenotypic strength on cell shape. (H) The jag-3 petal has both elongated (arrowhead) and round cells (arrow). (I) The jag-2 petal only has elongated cobblestone-shaped cells. Also note a striking difference in cell numbers between wild type (G) and jag-2 (I). For all panels distal is top and proximal is bottom. Scale bars: 20 µm, A-F and G-I.

View larger version (74K): [in a new window]   Fig. 3. Floral organ development in jag double mutants. (A) ant-9 flower with narrow organs. (B) ant-9 jag-3 flower with narrow reduced floral organs. Sepal (arrowhead) and petal (arrow). (C) fil-1 flower. (D) fil-1 jag-3 flower. (E) sup-5 flower. (F) sup-5 jag-3 flower.

View larger version (97K): [in a new window]   Fig. 4. Phenotypes of double mutants between jag and bract forming mutants, lfy, ap2 and ap1. (A) Bract subtending a lfy-6 flower. (B) Reduced bract forms at the base of lfy-6 jag-3 flower (arrowhead). (C,D) Close-up image of a lfy-6 jag-3 reduced bract (C) and a filamentous structure (D),. (E) lfy-5 flower with lateral and medial sepals. (F) lfy-5 jag-3 flower with lateral first whorl organs missing (arrowhead). (G) ap2-1 flower with bract-like sepals. (H) ap2-1 jag-3 flower with lateral first whorl organs missing (arrowhead). (I) ap1-1 inflorescence with bract-like sepals. (J) ap1-1 jag-3 inflorescence with reduced numbers of bract-like sepals (arrowhead).

View larger version (48K): [in a new window]   Fig. 5. Map-based cloning and sequence of JAG. (A) Schematic of positional cloning of the JAG locus showing the frequency of recombinant chromosomes identified in a mapping population with respect to molecular markers corresponding to BAC clones. Fine-scale mapping localized the JAG locus to the BAC T26J14 (black box). (B) Amino acid sequence of the JAG protein. Positions and nature of the jag-2 (asterisk) and jag-3 (black arrowhead) mutations are indicated. The EAR repression motif is boxed. A putative nuclear localization sequence is shown in bold font. The single C2H2-type zinc finger motif is underlined in black. A proline-rich motif is underlined in gray. (C) Amino acid alignment of the JAG C2H2 zinc finger domain with other Arabidopsis proteins. The positions of conserved cysteine and histidine residues involved in coordinating a zinc ion are indicated by asterisks. (D) Amino acid alignment of the JAG EAR repression motif with other Arabidopsis proteins. The EAR repression consensus motif is indicated below. Identical residues are in black boxes; similar residues in gray boxes.

View larger version (150K): [in a new window]   Fig. 6. Expression pattern of JAG. (A-L) RNA localization by in situ hybridization with JAG antisense probe. (A) Late transition stage embryo. (B) Heart stage embryo. (C) Torpedo stage embryo. (D) and (E) Consecutive longitudinal section through a seedling 3.5 days after germination. (F) Seedling 7 days after germination. (G) Longitudinal section of inflorescence meristem and early floral buds. (H) Transverse section of inflorescence meristem. (I) Expression in stage 3 floral bud. (J) Transverse section of stamen primordium of stage 6 flower. (K) Stage 8 petal primordium (arrowhead) longitudinal section. (L) Transverse section of stage 10 gynoecium. (M) Inflorescence of lfy-6 mutant with JAG expression in early bract primordia (arrows). (N) Confocal optical section showing the JAG::VENUS transgene expressed in seedling 4 days after germination. Nuclear expression of the fusion protein is confined to the growing region (arrowhead) of the leaf primordium. (O) JAG-VENUS subcellular localization (yellow) in cells of a leaf primordium. (P) Hoechst 33342 nuclear staining (blue). (Q) Merged image of O and P showing nuclear co-localization (green). Meristem is indicated by asterisk in some panels. Scale bar: 100 µm (G,K); 30 µm (O-Q); 50 µm in all other panels.

View larger version (149K): [in a new window]   Fig. 7. 35S::JAG Misexpression. (A) Wild-type (left) and 35S::JAG (middle and right) seedling phenotypes, the latter with greening of hypocotyl (arrowhead) and variable fusion of cotyledons. (B) Vasculature of wild-type cotyledon. Arrowhead indicates midvein. (C) Vasculature of 35S::JAG fused cotyledons shows no obvious midvein. (D) to (I) 35S::JAG vegetative and floral defects. (D) Fusion of rosette leaves (arrow) and cotyledon (c) fusion along the petiole margins. (E) Bract formation at the base of the flower pedicel. (F) Stipule outgrowth from the lateral margins at the base of the leaf (arrowhead). (G) Growth of leaf-like tissue and stellate trichomes (arrowhead) on the stem. (H) Abnormal flowers emerging from the inflorescence. (I) Flower with fused sepals connected to abnormal pedicel (arrowhead). (J-Q) SEM analysis of wild-type pedicel (J,K), stem with trichome (L), and leaf with pavement cells (M) in comparison to 35S::JAG pedicel (N,O,Q) and 35S:JAG stem (P). 35S::JAG pedicel cell types resemble leaf pavement cells. Trichome (arrowhead) and large petal-like cell (asterisk) are indicated in O. Fusion between adjacent sepals (arrowhead) is indicated in Q. Scale bars 1 mm (A); 500 µm (B); 200 µm (C); 100 µm (J,N,Q); (K), (L), (M), (O), (P) 10 µm (K-M, O, P).

View larger version (85K): [in a new window]   Fig. 8. Transverse sections of stem and leaf showing vegetative structure. (A) wild-type stem with central pith (p). (B) 35S::JAG stem is larger in diameter than wild type with numerous finger-like projections and central pith (p). (C) Wild-type leaf showing upper and lower epidermis (arrowheads), palisade mesophyll (pm), spongy mesophyll (sm) and vascular bundle composed of phloem cells (black arrow) and xylem cells (white arrow). Adaxial surface of leaf is at the top and abaxial surface is at the bottom. (D) Close-up image of finger-like projection of the 35S::JAG stem with epidermis (arrowhead), phloem (black arrow) and xylem (white arrow). (E,F) Region of wild-type (E) and 35S::JAG (F) stem with outer epidermis (arrowhead), cortex (c), phloem (black arrow) and xylem (white arrow). Scale bar: 100 µm (A); 200 µm (B); 100 µm (C-F).

View larger version (87K): [in a new window]   Fig. 9. Misexpression of JAG in flowers with pAP1:LhG4 6XOP::JAG. (A) Inflorescence with variable leaf-like organs in place of flowers. Organs are club-shaped with leaf-like pedicels after the transition to reproductive development. (B) A mature leaf-like organ. Scale bar: 100 µm.