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


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

First published online September 9, 2004
doi: 10.1242/10.1242/dev.01306

Development 131, 4697-4707 (2004)
Published by The Company of Biologists 2004
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 HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Pfluger, J.
Right arrow Articles by Zambryski, P.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Pfluger, J.
Right arrow Articles by Zambryski, P.
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati   Add to Twitter  
What's this?

The role of SEUSS in auxin response and floral organ patterning

Jennifer Pfluger and Patricia Zambryski

Department of Plant and Microbial Biology, 111 Koshland Hall, University of California, Berkeley, CA 94720-3102, USA



View larger version (68K):

[in a new window]
  		Fig. 1. seu-3 modifies ett-7 in all floral whorls. (A-E) Top-down views. (F-J) Side views. (A) Wild-type flower showing four evenly spaced petals, six stamens and the stigma at the top of the central gynoecium. (B) seu-3 flower showing smaller, narrower petals, shorter stamens and a split gynoecium. (C) Close up of seu-3 gynoecium in B showing two balls of stigmatic tissue and two splayed valve tips. (D) ett-7 flower showing five petals, six stamens and a wide stigma resulting from overproliferation of apical tissues. (E) ett-7 seu-3 flower showing one very narrow petal (arrow), one stamen (arrowhead) and a round stigma. (F) Wild-type flower showing two full ovaries, with arrows delimiting top and bottom of the right valve. (G) seu-3 flower showing smaller petals and shorter pollenless stamens. Ovaries are full length, but the unfused distal gynoecium results in a horn-like protrusion (arrow) and an exposed ovule (arrowhead). (H) ett-7 gynoecium has only one reduced ovary (arrows at valve boundaries), with the distal gynoecium appearing Y-shaped from basalized stigmatic and stylar tissue (arrowhead). (I) ett-7 seu-3 flower showing reduced filamentous sepals and petals (arrowhead and arrow, respectively), few stamens and a stalk-like gynoecium. (J) ett-7 seu-3 flower showing one normal stamen, one stamen fused along its entire length with the gynoecium (arrowheads) and one valve that is open at the top (arrow). Genotypes described are in Col. Scale bars: 1 mm.

 


View larger version (51K):

[in a new window]
  		Fig. 2. Effects of ett-7 seu-3 on floral meristem patterning. Numbers refer to stages of flower development (Smyth et al., 1990Go). (A) Wild-type inflorescence shows four evenly spaced sepal primordia arising from stage 3 and 4 floral meristems (arrows and arrowheads), and sepals completely enveloping the floral buds by stage 6. (B) Like wild type, seu-3 has four uniformly positioned sepal primordia (arrows and arrowheads), but sepals are smaller and often do not tightly enclose the inner organs (compare the amount of exposed floral meristem at the asterisks in A and B). (C) ett-7 flowers characteristically have five sepals, with an extra abaxial sepal (top arrowhead) (D,E) A greater number of developing meristems are present in ett-7 seu-3 than in either single mutant. ett-7 seu-3 floral meristems are distinctive by stages 3-4, when an uneven ring of sepal primordia tissue becomes evident (r). As the flower develops, sepals grow out erratically, causing some to be fused and some to be filamentous. Tiny petal primordia in stage 5 and 6 meristems are indicated by arrowheads. Genotypes described are in Col. Scale bars are 0.1 mm.

 


View larger version (38K):

[in a new window]
  		Fig. 3. Flowers of ag-1 (A), seu-1 (B), ag-1 seu-1 (C) and ag-1 ett-11 seu-1 (D). Stamenoid sepals in seu-1 (arrow in B) do not occur in ag-1 seu-1 (arrow in C). Filamentous organs in ett seu are also present in ag-1 ett-11 seu-1 (compare Fig. 1I with D). The floral meristem in ag-1 ett-11 seu-1 continues to grow but occasionally stops producing lateral organs (arrowhead in D). Genotypes described are in Ler. Scale bars: 1 mm.

 


View larger version (54K):

[in a new window]
  		Fig. 4. seu-3 displays hallmark auxin response phenotypes. (A) seu-3 is shorter than wild type with increased shoot branching. (B) The three seu-3 seedlings (right) produce fewer lateral roots than the three wild-type seedlings (left). (C) seu-3 roots are longer than wild-type roots when grown on media containing 100 nM NAA. This indicates that seu-3 is not as sensitive to the inhibitory effects of exogenous auxin on root elongation. (D) Quantification of differences in primary root length in seedlings grown on media lacking hormone relative to seedlings grown on media containing NAA (n≥24). *P<0.01 (t-test). (E,F) Close-up of seedling apices from C. Compare epinastic cotyledons of wild type (E) with more upright cotyledons of seu-3 (F). (G) Angle of root tips in light grown seedlings, 24 hours after rotating the plates 90°. Length of each line represents the number of seedlings with root tips growing at that angle, in 12 30° categories (n=52). seu-3 roots reorient to the gravity vector less successfully than do wild-type roots [P<1*10-4 (t-test)]. Genotypes described are in Col. Scale bars: 1 cm.

 


View larger version (87K):

[in a new window]
  		Fig. 5. Seedlings expressing the auxin response reporter DR5::GUS. DR5 is expressed more strongly in wild type (A,C,E) than in seu-3 (B,D,F). (A) Roots assayed for GUS activity show GUS staining extending from the root meristem into the root cap (arrowhead) and stele (arrow) in wild type. (B) seu-3 roots display a substantial decrease in GUS product, with only weak DR5 expression in the root cap (arrowhead), and none in the vasculature (arrow). (C,D) Five-day-old seedlings show first leaves with more extensive GUS activity in wild type, spatially marking incipient and developing veins, whereas in seu-3 GUS product is seen only at the distal leaf tip and in hydathodes. (E,F) Seven-day-old seu-3 seedlings do not show a recovery in GUS activity. As leaves grow and mature, wild-type GUS activity parallels the basipetal differentiation of vascular tissue. No GUS product is seen in seu-3 leaves at similar stages (compare 1, 2 and 3). Genotypes described are in Col.

 


View larger version (103K):

[in a new window]
  		Fig. 6. Effect of seu-3 on the auxin regulatory mutant pid-1. (A) pid-1 inflorescence showing flowers with large, supernumerary petals that are occasionally fused (arrow). (B) pid-1 flower showing gynoecium with an infrequent ovary that, like ett ovaries, is reduced in size (arrows indicate top and bottom of single valve). (C) Top-down view of pid-1 seu-3 inflorescence showing naked gynoecia. A swollen ring of tissue appears in place of the outer whorl organs. Rarely, a sepal originates from this band of tissue (arrow). (D) Side view of pid-1 seu-3 inflorescence showing that the swollen tissue in C is continuous with the pedicel. Occasionally there is a less defined boundary between the pedicel and the gynoecium (arrowhead). (E) pid-1 seu-3 gynoecium that resembles pid-1 single mutant gynoecium, a stalked organ without valves. Two filamentous outer whorl organs are apparent. (F) pid-1 seu-3 gynoecium that is split into multiple stigma-capped stalks. Although no valves have differentiated, the gynoecium still produces ovules (arrowhead). Genotypes described are in Ler.

 


View larger version (15K):

[in a new window]
  		Fig. 7. Distribution of floral organ numbers in 105 wild-type flowers, 51 pid-1 flowers, 76 seu-3 flowers and 50 pid-1 seu-3 flowers. Organs fused together were counted as one organ. Gynoecia in whorl 4 were scored as 0, 1 or 2 depending on whether valve tissue was present on none, one or both sides of the gynoecium. pid-1 seu-3 flowers have very few outer whorl organs. All genotypes are in Ler.

 


View larger version (46K):

[in a new window]
  		Fig. 8. Yeast two hybrid assay. (A) Schematic of bait and prey combinations. (B) Growth of yeast on selection for bait and prey plasmids only (+Ura). (C) Growth of yeast on selection (uracil biosynthesis) for bait and prey interaction (–Ura). BD, empty vector pBD; AD, empty vector pGAD424; SEU-AD, SEU in pGAD424; ETT-BD, ETT in pBD; UFO-BD, UNUSUAL FLORAL ORGANS in pAS1; ARF-BD1, ARF1 in pGBT9.

 


View larger version (13K):

[in a new window]
  		Fig. 9. Experimental model of SEU function. The SEU transcriptional co-regulator controls floral meristem patterning in response to auxin in conjunction with ETT, an ARF transcription factor. ETT binds to AuxREs in the promoters of auxin responsive genes. SEU interacts with ETT and other regulatory factors to affect transcription of those targets.

 

Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Reddit Reddit   Add to Technorati Technorati   Add to Twitter Twitter    What's this?



© The Company of Biologists Ltd 2004