Genetic control of identity and growth in the early Arabidopsis embryo
Weijers, D. - \ 2014
Biochemical Society Transactions 42 (2014)2. - ISSN 0300-5127 - p. 346 - 351.
auxin-response - transcription factor - cell fate - root-meristem - early embryogenesis - pattern-formation - shoot meristem - monopteros - wuschel - expression
Plants can grow complex and elaborate structures, in some species for thousands of years. Despite the diversity in form and shape, plants are built from a limited number of fundamental tissue types, and their arrangement is deeply conserved in the plant kingdom. A key question in biology is how these fundamental tissues, i.e. epidermal, ground and vascular tissue, are specified and organized in time and space. In the present paper, I discuss the use of the early Arabidopsis embryo as a model system to dissect the control of tissue formation and patterning, as well as the specification of the stem cells that sustain post-embryonic growth. I present recent insights into the molecules and mechanisms that control both the specification and the subsequent growth of the different cell types within the embryonic root. Finally, I discuss major unanswered questions and future challenges in using the embryo as a model to decipher the regulatory logic of plant development
Rooting plant development
Scheres, B. - \ 2013
Development 140 (2013)5. - ISSN 0950-1991 - p. 939 - 941.
arabidopsis root - cell fate - meristem - differentiation - mechanism - shoot - framework - epidermis - division - pattern
In 1993, we published a paper in Development detailing the anatomical structure of the Arabidopsis root. The paper described how root growth was maintained by the precisely tuned activity of a small set of 'initials', which acted as the source of dividing and differentiating cells, and how these stem cell-like cells surrounded a few infrequently dividing cells. This work underpinned subsequent research on root developmental biology and sparked a detailed molecular analysis of how stem cell groups are positioned and maintained in plants.
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
Regeneration of zygotic-like microspore-derived embryos suggests an important role for the suspensor in early embryo patterning
Supena, E.D.J. ; Winarto, P.S. ; Riksen, T. ; Dubas, E. ; Lammeren, A.A.M. van; Custers, J.B.M. - \ 2008
Journal of Experimental Botany 59 (2008)4. - ISSN 0022-0957 - p. 803 - 814.
brassica-napus l - apical-basal axis - l cv topas - arabidopsis-thaliana - somatic embryogenesis - plant embryogenesis - root-meristem - bilateral symmetry - auxin distribution - cell fate
The inaccessibility of the zygote and proembryos of angiosperms within the surrounding maternal and filial tissues has hampered studies on early plant embryogenesis. Somatic and gametophytic embryo cultures are often used as alternative systems for molecular and biochemical studies on early embryogenesis, but are not widely used in developmental studies due to differences in the early cell division patterns with seed embryos. A new Brassica napus microspore embryo culture system, wherein embryogenesis highly mimics zygotic embryo development, is reported here. In this new system, the donor microspore first divides transversely to form a filamentous structure, from which the distal cell forms the embryo proper, while the lower part resembles the suspensor. In conventional microspore embryogenesis, the microspore divides randomly to form an embryonic mass that after a while establishes a protoderm and subsequently shows delayed histodifferentiation. In contrast, the embryo proper of filament-bearing microspore-derived embryos undergoes the same ordered pattern of cell division and early histodifferentiation as in the zygotic embryo. This observation suggests an important role for the suspensor in early zygotic embryo patterning and histodifferentiation. This is the first in vitro system wherein single differentiated cells in culture can efficiently regenerate embryos that are morphologically comparable to zygotic embryos. The system provides a powerful in vitro tool for studying the diverse developmental processes that take place during the early stages of plant embryogenesis.
Use of Petunia to unravel plant meristem functioning
Angenent, G.C. ; Stuurman, J. ; Snowden, K.C. ; Koes, R. - \ 2005
Trends in Plant Science 10 (2005)5. - ISSN 1360-1385 - p. 243 - 250.
mads-box genes - shoot apical meristem - floral organ - arabidopsis-thaliana - flower development - inflorescence development - antirrhinum-majus - ovule development - cell fate - identity
In the past decade, enormous progress has been made in our understanding of the molecular and genetic control of meristem growth, maintenance and differentiation into plant organs. Several model plants have contributed to our current knowledge of meristem function. Research using Petunia has had a substantial share in this progress. Integration of information obtained from this species gives clues about the common and diverged pathways underlying the formation and functioning of plant meristems
Mis-expression of the CLV3/ESR-like gene CLE19 in Arabidopsis leads to a consumption of root meristem
Fiers, M.A. ; Hause, G. ; Boutilier, K.A. ; Casamitjana-Martinez, E. ; Weijers, D. ; Offringa, R. ; Geest, L. van der; Lookeren Campagne, M.M. van; Liu, C.M. - \ 2004
Gene 327 (2004)1. - ISSN 0378-1119 - p. 37 - 49.
shoot meristem - cell fate - clavata3 - clv3 - transformation - polypeptide - proteins - pathway - pattern - tissues
Mild heat shock treatment (32 °C) of isolated Brassica napus microspores triggers a developmental switch from pollen maturation to embryo formation. This in vitro system was used to identify genes expressed in globular to heart-shape transition embryos. One of the genes isolated encodes a putative extra-cellular protein that exhibits high sequence similarity with the in silico identified CLV3/ESR-related 19 polypeptide from Arabidopsis (AtCLE19) and was therefore named BnCLE19. BnCLE19 is expressed in the primordia of cotyledons, sepals and cauline leaves, and in some pericycle cells in the root maturation zone. Mis-expression of BnCLE19 or AtCLE19 in Arabidopsis under the control of the CaMV 35S promoter resulted in a dramatic consumption of the root meristem, the formations of pin-shaped pistils and vascular islands. These results imply a role of CLE19 in promoting cell differentiation or inhibiting cell division
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.
Experimental and genetic analysis of root development in Arabidopsis thaliana
Scheres, Ben ; McKhann, Heather ; Berg, Claudia Van Den; Willemsen, Viola ; Wolkenfelt, Harald ; Vrieze, Geert De; Weisbeek, Peter - \ 1996
Plant and Soil 187 (1996)1. - ISSN 0032-079X - p. 97 - 105.
Arabidopsis - cell fate - embryogenesis - laser ablation - root meristem
The cellular organisation of the Arabidopsis thaliana root is remarkably regular. A fate map of the primary root and root meristem that predicts the developmental destinies of cells within the embryonic root primordium has been constructed. Nevertheless, laser ablation experiments demonstrate that root meristem cells develop according to position and not according to lineage. Mutational analysis has identified genes required for cell specification in the radial as well as in the apical-basal dimension. The corresponding gene functions appear to be necessary during embryogenesis for the formation of a correctly patterned primary root.