spacer gif spacer gif spacer gif spacer gif spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

This Article
Right arrow Summary Freely available
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Long, J. A.
Right arrow Articles by Barton, M. K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Long, J. A.
Right arrow Articles by Barton, M. K.

Transformation of shoots into roots in Arabidopsis embryos mutant at the TOPLESS locus

Jeff A. Long1,3, Scott Woody1, Scott Poethig2, Elliot M. Meyerowitz3 and M. Kathryn Barton1,*,{dagger}

1 Department of Genetics and Program in Cellular and Molecular Biology, University of Wisconsin-Madison, Madison, WI, USA
2 Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
3 Division of Biology, California Institute of Technology, Pasadena, CA, USA
* Present address: Department of Plant Biology, Carnegie Institution of Washington, 260 Panama Street, Stanford, CA 94305, USA



View larger version (31K):

[in a new window]
  		Fig. 1. Representative phenotypes of seedlings homozygous for the tpl-1 mutation. (A) Wild-type seedling. (B) tpl-1 homozygote that has developed a single cotyledon and lacks a shoot apical meristem. (C) tpl-1 homozygotes that has developed a cup-shaped cotyledon and no shoot apical meristem. (D) tpl-1 homozygote that has developed with no detectable cotyledon tissue or shoot apical meristem. (E) tpl-1 homozygote that has developed both an apical (a) and a basal (b) root. Scale bars: 1 mm.

 


View larger version (118K):

[in a new window]
  		Fig. 2. Scanning electron micrographs of topless seedlings. (A) Wild-type seedling. (B) topless mutant seedling with a single cotyledon and no shoot apical meristem. (C) topless mutant seedling with a cup-shaped cotyledon and no SAM. (D) topless mutant seedling lacking cotyledons and SAM. (E) topless mutant seedling with apical root replacing the shoot apical meristem and cotyledons. (F) Close-up of apical root. (G) topless seedling with mixed fates. Root hairs are present on a reduced cotyledon. h, hypocotyl; c, cotyledon; a, apical root; b, basal root; rh, root hairs. Scale bar: 0.2 mm in A and C; 0.37 mm in B and E; 0.43 mm in D and G; 0.1 mm in F.

 


View larger version (110K):

[in a new window]
  		Fig. 3. DIC images of apical and basal topless roots. (A) Basal root. (B) Apical root. Scale bar: 0.1 mm.

 


View larger version (165K):

[in a new window]
  		Fig. 4. DIC images of developing wild-type and topless embryos. All seedlings developed at 29°C. (A) Wild-type heart stage embryo. (B) Wild-type torpedo stage embryo. (C) Wild-type mature embryo. (D) topless heart stage embryo. (E) topless torpedo stage embryo. (F) topless mature embryo. c, cotyledon; s, suspensor; sam, shoot apical meristem; ram, root apical meristem. Scale bars: in E, 25 µm for A,B,D,E; in F for 25 µm C,F.

 


View larger version (116K):

[in a new window]
  		Fig. 5. Gene expression patterns in topless mutant embryos. (A) Expression of STM in wild-type heart stage embryo. (B) Expression of STM in a topless embryo (sibling to embryo in A). (C) UFO expression in topless mutant embryo. (D) UBIQUITIN expression in topless mutant embryo. (E) ANT expression in wild-type heart stage embryo. (F) ANT expression in topless mutant. (G) KNAT1 expression in wild-type walking stick stage embryo. (H) KNAT1 expression in topless embryo. (I) SCARECROW expression in wild-type globular embryos. (J) SCARECROW expression in topless mutant embryos. Scale bars: in A, 25 µm for A-F; in G, 50 µm for G,H; in I, 25 µm for I,J.

 


View larger version (72K):

[in a new window]
  		Fig. 6. Expression of the LENNY (lenticular cell), DR5 (auxin maximum) and J1092 (root cap) markers in wild-type and topless mutant embryos. (A) Wild-type heart stage embryo expressing the LENNY reporter in the lenticular cell and adjacent cells. (B) Wild-type mature stage embryo expressing the LENNY reporter. (C) Wild-type mature stage embryo expressing the J1092 reporter expressed in the root cap. (D) topless embryo showing a weak signal for the LENNY reporter at the apical pole. (E) topless embryo with LENNY expression at both poles. Note that the apical pole is wider and does not yet show root-like cellular organization. (F) topless embryo with LENNY expression at both poles. (G) topless embryo arrested as an elongated embryo. Notice the two foci of LENNY expression connected to each other. (H) topless embryo arrested at globular stage. LENNY reporter is expressed throughout. (I) A rare tpl-1 embryo that expresses the DR5 reporter in the apical region of the embryo. In these rare individuals, expression is typically patchy. (J) Expression of the J1092 root cap marker in a homozygous tpl-1 mutant embryo. (K) Image in J overlaid on Nomarski image of embryo. Scale bars: 25 µm in A,G,H; 65 µm in B,C; 50 µm in D-F,I-K.

 


View larger version (103K):

[in a new window]
  		Fig. 7. Phenotypes of mutants homozygous for both tpl-1 and mp-7. (A) Seedling to left is mp-7 homozygote. Seedling to right is mp-7 tpl-1 homozygote. Both seedlings developed at 24°C. The double mutant has a more well-developed hypocotyl than the mp-7 single mutant. (B) Cleared mp-7 single mutant (grown at 24°C) showing lack of vasculature in the hypocotyl ‘stub’. (C) Cleared mp-7 tpl-1 double mutant (grown at 24°C) showing vasculature extending down into the more well developed hypocotyl. (D) Homozygous mp-7 single mutant grown at 29°C. (E) Homozygous mp-7 tpl-1 double mutant grown at 29°C. The double mutant is able to develop an apical root. Scale bar: 200 µm in A; 100 µm in B,C; 50 µm in D,E.

 


View larger version (16K):

[in a new window]
  		Fig. 8. Effect of temperature shift on topless embryo development. Number of embryos that developed an apical root when shifted from 29°C to 17°C at fertilization, 0/126; at 8-16 cells, 6/127; at 16-32 cells, 8/154; at 32-64 cells, 4/126; at 64 cells to transition stage, 26/175; at transition to early heart stage, 43/103; at midheart stage, 48/91; at torpedo stage, 74/116. Number of embryos that developed an apical root when shifted from 17°C to 29°C at fertilization, 142/149; at 8-16 cells, 93/143; at 16-32 cells, 113/134; at 32-64 cells, 46/85; at 64 cells to transition stage, 92/195; at transition to early heart stage, 31/143; at midheart stage, 18/127.

 




© The Company of Biologists Ltd 2002