- J. Chandler (1)
- M. Cole (1)
- P. Comelli (1)
- R. Datla (1)
- S. El-Showk (1)
- J. Friml (1)
- Y. Helariutta (1)
- H. Help (1)
- B. Jacobs (1)
- M.A.C.J. Kwaaitaal (1)
- T. Laux (1)
- B.K. Moller (1)
- A.P. Mordhorst (1)
- A. Pekka Mahonen (1)
- M.Z. Ren (1)
- B.J.G. Scheres (1)
- G. Selvaraj (1)
- S. Stone (1)
- P. Venglat (1)
- S.C. Vries de (1)
- C.W. Vroemen (1)
- E. Wang (1)
- H. Wang (1)
- D. Weijers (4)
- R. Wen (1)
- W. Werr (1)
- D.Q. Xiang (1)
- W. Xiao (1)
- H. Yang (1)
POPCORN Functions in the Auxin Pathway to Regulate Embryonic Body Plan and Meristem Organization in Arabidopsis
Xiang, D.Q. ; Yang, H. ; Venglat, P. ; Cao, Y.G. ; Wen, R. ; Ren, M.Z. ; Stone, S. ; Wang, E. ; Wang, H. ; Xiao, W. ; Weijers, D. ; Berleth, T. ; Laux, T. ; Selvaraj, G. ; Datla, R. - \ 2011
The Plant Cell 23 (2011)12. - ISSN 1040-4651 - p. 4348 - 4367.
stem-cell niche - cup-shaped-cotyledon - shoot meristem - wild-type - gene - embryogenesis - wuschel - fate - monopteros - thaliana
The shoot and root apical meristems (SAM and RAM) formed during embryogenesis are crucial for postembryonic plant development. We report the identification of POPCORN (PCN), a gene required for embryo development and meristem organization in Arabidopsis thaliana. Map-based cloning revealed that PCN encodes a WD-40 protein expressed both during embryo development and postembryonically in the SAM and RAM. The two pcn alleles identified in this study are temperature sensitive, showing defective embryo development when grown at 22 degrees C that is rescued when grown at 29 degrees C. In pcn mutants, meristem-specific expression of WUSCHEL (WUS), CLAVATA3, and WUSCHEL-RELATED HOMEOBOX5 is not maintained; SHOOTMERISTEMLESS, BODENLOS (BDL) and MONOPTEROS (MP) are misexpressed. Several findings link PCN to auxin signaling and meristem function: ectopic expression of DR5(rev):green fluorescent protein (GFP), pBDL:BDL-GFP, and pMP:MP-beta-glucuronidase in the meristem; altered polarity and expression of pPIN1:PIN1-GFP in the apical domain of the developing embryo; and resistance to auxin in the pcn mutants. The bdl mutation rescued embryo lethality of pcn, suggesting that improper auxin response is involved in pcn defects. Furthermore, WUS, PINFORMED1, PINOID, and TOPLESS are dosage sensitive in pcn, suggesting functional interaction. Together, our results suggest that PCN functions in the auxin pathway, integrating auxin signaling in the organization and maintenance of the SAM and RAM.
A mutually inhibitory interaction between auxin and cytokinin specifies vascular pattern in roots.
Bishopp, A. ; Help, H. ; El-Showk, S. ; Weijers, D. ; Scheres, B.J.G. ; Friml, J. ; Benkova, E. ; Pekka Mahonen, A. ; Helariutta, Y. - \ 2011
Current Biology 21 (2011)11. - ISSN 0960-9822 - p. 917 - 926.
cup-shaped-cotyledon - stem-cell niche - class iiihd-zip - arabidopsis root - meristem activity - hormonal-control - gene family - embryo - efflux - embryogenesis
Background Whereas the majority of animals develop toward a predetermined body plan, plants show iterative growth and continually produce new organs and structures from actively dividing meristems. This raises an intriguing question: How are these newly developed organs patterned? In Arabidopsis embryos, radial symmetry is broken by the bisymmetric specification of the cotyledons in the apical domain. Subsequently, this bisymmetry is propagated to the root promeristem. Results Here we present a mutually inhibitory feedback loop between auxin and cytokinin that sets distinct boundaries of hormonal output. Cytokinins promote the bisymmetric distribution of the PIN-FORMED (PIN) auxin efflux proteins, which channel auxin toward a central domain. High auxin promotes transcription of the cytokinin signaling inhibitor AHP6, which closes the interaction loop. This bisymmetric auxin response domain specifies the differentiation of protoxylem in a bisymmetric pattern. In embryonic roots, cytokinin is required to translate a bisymmetric auxin response in the cotyledons to a bisymmetric vascular pattern in the root promeristem. Conclusions Our results present an interactive feedback loop between hormonal signaling and transport by which small biases in hormonal input are propagated into distinct signaling domains to specify the vascular pattern in the root meristem. It is an intriguing possibility that such a mechanism could transform radial patterns and allow continuous vascular connections between other newly emerging organs.
Auxin control of embryo patterning
Moller, B.K. ; Weijers, D. - \ 2009
Cold Spring Harbor Perspectives in Biology 1 (2009)5. - ISSN 1943-0264 - p. a001545 - a001545.
homeodomain finger proteins - shoot apical meristem - cup-shaped-cotyledon - arabidopsis-embryo - plant embryogenesis - axis formation - basal axis - cell fate - genes - thaliana
Plants start their life as a single cell, which, during the process of embryogenesis, is transformed into a mature embryo with all organs necessary to support further growth and development. Therefore, each basic cell type is first specified in the early embryo, making this stage of development excellently suited to study mechanisms of coordinated cell specification - pattern formation. In recent years, it has emerged that the plant hormone auxin plays a prominent role in embryo development. Most pattern formation steps in the early Arabidopsis embryo depend on auxin biosynthesis, transport, and response. In this article, we describe those embryo patterning steps that involve auxin activity, and we review recent data that shed light on the molecular mechanisms of auxin action during this phase of plant development
DORNRÖSCHEN is a direct target of the auxin response factor MONOPTEROS in the Arabidopsis embryo
Cole, M. ; Chandler, J. ; Weijers, D. ; Jacobs, B. ; Comelli, P. ; Werr, W. - \ 2009
Development 136 (2009). - ISSN 0950-1991 - p. 1643 - 1651.
cup-shaped-cotyledon - gene family-members - axis formation - vascular development - transcription factor - plant development - aux/iaa proteins - leaf formation - root-formation - cell fate
DORNRÖSCHEN (DRN), which encodes a member of the AP2-type transcription factor family, contributes to auxin transport and perception in the Arabidopsis embryo. Live imaging performed with transcriptional or translational GFP fusions shows DRN to be activated in the apical cell after the first zygotic division, to act cell-autonomously and to be expressed in single cells extending laterally from the apical shoot stem-cell zone at the position of incipient leaf primordia. Here, we show that the Auxin response factor (ARF) MONOPTEROS (MP) directly controls DRN transcription in the tips of the embryonic cotyledons, which depends on the presence of canonical Auxin response elements (AuxREs), potential ARF-binding sites flanking the DRN transcription unit. Chromatin immunoprecipitation experiments show that MP binds in vivo to two AuxRE-spanning fragments in the DRN promoter, and that MP is required for expression of DRN in cotyledon tips. Hence, DRN represents a direct target of MP and functions downstream of MP in cotyledon development
The CUP-SHAPED COTYLEDON3 gene is required for boundary and shoot meristem formation in Arabidopsis
Vroemen, C.W. ; Mordhorst, A.P. ; Albrecht, C. ; Kwaaitaal, M.A.C.J. ; Vries, S.C. de - \ 2003
The Plant Cell 15 (2003). - ISSN 1040-4651 - p. 1563 - 1577.
cup-shaped-cotyledon - pattern-formation - apical meristem - cell fate - flanking sequences - plant development - root development - enhancer trap - stem-cells - thaliana
From an enhancer trap screen for genes expressed in Arabidopsis embryos, we identified a gene expressed from the octant stage onward in the boundary between the two presumptive cotyledons and in a variety of postembryonic organ and meristem boundaries. This gene, CUP-SHAPED COTYLEDON3 (CUC3), encodes a putative NAC-domain transcription factor that is homologous with CUC1 and CUC2. Analysis of a CUC3 hypomorph and a putative cuc3 null mutant indicates that CUC3 function is partially redundant with that of CUC1 and CUC2 in the establishment of the cotyledon boundary and the shoot meristem, thus revealing an even higher degree of redundancy in this class of genes than was thought previously. The CUC3 expression pattern, the cuc3 phenotypes, and CUC3 expression in a series of shoot meristem mutants and transgenes suggest a primary role for CUC3 in the establishment of boundaries that contain cells with low proliferation and/or differentiation rates. The CUC-mediated establishment of such boundaries may be essential for the initiation of shoot meristems.