A novel two-component hybrid molecule regulates vascular morphogenesis of the <i>Arabidopsis</i> root

Mähönen, Ari Pekka; Bonke, Martin; Kauppinen, Leila; Riikonen, Marjukka; Benfey, Philip N.; Helariutta, Yrjö

doi:10.1101/gad.189200

Cited by 521 publications

(479 citation statements)

References 35 publications

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“…Enlarged embryos suggest that cytokinins may play a role in controlling the cell division rate in maturing embryos. Similarly, a specific role for cytokinins in controlling cell divisions during the establishment of the embryonic vasculature was demonstrated recently in a mutant of the cytokinin receptor CRE1/WOL/AHK4 (Mähönen et al, 2000). Early consequences of cytokinin deficiency might have been missed in the AtCKX-overexpressing plants, because the 35S promoter driving AtCKX expression becomes active late during embryogenesis (Custers et al, 1999).…”

Section: A Role For Cytokinins During Reproductive Developmentmentioning

confidence: 99%

Cytokinin-Deficient Transgenic Arabidopsis Plants Show Multiple Developmental Alterations Indicating Opposite Functions of Cytokinins in the Regulation of Shoot and Root Meristem Activity

Werner

Motyka

Laucou³

et al. 2003

Plant Cell

1,322

1,243

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Cytokinins are hormones that regulate cell division and development. As a result of a lack of specific mutants and biochemical tools, it has not been possible to study the consequences of cytokinin deficiency. Cytokinin-deficient plants are expected to yield information about processes in which cytokinins are limiting and that, therefore, they might regulate. We have engineered transgenic Arabidopsis plants that overexpress individually six different members of the cytokinin oxidase/dehydrogenase ( AtCKX ) gene family and have undertaken a detailed phenotypic analysis. Transgenic plants had increased cytokinin breakdown (30 to 45% of wild-type cytokinin content) and reduced expression of the cytokinin reporter gene ARR5 : GUS ( ␤ -glucuronidase). Cytokinin deficiency resulted in diminished activity of the vegetative and floral shoot apical meristems and leaf primordia, indicating an absolute requirement for the hormone. By contrast, cytokinins are negative regulators of root growth and lateral root formation. We show that the increased growth of the primary root is linked to an enhanced meristematic cell number, suggesting that cytokinins control the exit of cells from the root meristem. Different AtCKX-green fluorescent protein fusion proteins were localized to the vacuoles or the endoplasmic reticulum and possibly to the extracellular space, indicating that subcellular compartmentation plays an important role in cytokinin biology. Analyses of promoter: GUS fusion genes showed differential expression of AtCKX genes during plant development, the activity being confined predominantly to zones of active growth. Our results are consistent with the hypothesis that cytokinins have central, but opposite, regulatory functions in root and shoot meristems and indicate that a fine-tuned control of catabolism plays an important role in ensuring the proper regulation of cytokinin functions.

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Section: A Role For Cytokinins During Reproductive Developmentmentioning

confidence: 99%

Cytokinin-Deficient Transgenic Arabidopsis Plants Show Multiple Developmental Alterations Indicating Opposite Functions of Cytokinins in the Regulation of Shoot and Root Meristem Activity

Werner

Motyka

Laucou³

et al. 2003

Plant Cell

1,322

1,243

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“…For in situ hybridization in sections using SHR probe, sectioning and preparation of probes were done as described by Mähönen et al (2000). For cortexspecific expression, whole-mount in situ hybridizations were performed as described by Hejátko et al (2006).…”

Section: Light Microscopymentioning

confidence: 99%

“…Images were acquired using an Olympus fluorescence microscope. Fuchsin staining was done as described by Mähönen et al (2000).…”

Section: Fluorescence Microscopymentioning

confidence: 99%

Arabidopsis BIRD Zinc Finger Proteins Jointly Stabilize Tissue Boundaries by Confining the Cell Fate Regulator SHORT-ROOT and Contributing to Fate Specification

et al. 2015

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Plant cells cannot rearrange their positions; therefore, sharp tissue boundaries must be accurately programmed. Movement of the cell fate regulator SHORT-ROOT from the stele to the ground tissue has been associated with transferring positional information across tissue boundaries. The zinc finger BIRD protein JACKDAW has been shown to constrain SHORT-ROOT movement to a single layer, and other BIRD family proteins were postulated to counteract JACKDAW's role in restricting SHORT-ROOT action range. Here, we report that regulation of SHORT-ROOT movement requires additional BIRD proteins whose action is critical for the establishment and maintenance of the boundary between stele and ground tissue. We show that BIRD proteins act in concert and not in opposition. The exploitation of asymmetric redundancies allows the separation of two BIRD functions: constraining SHORT-ROOT spread through nuclear retention and transcriptional regulation of key downstream SHORT-ROOT targets, including SCARECROW and CYCLIND6. Our data indicate that BIRD proteins promote formative divisions and tissue specification in the Arabidopsis thaliana root meristem ground tissue by tethering and regulating transcriptional competence of SHORT-ROOT complexes. As a result, a tissue boundary is not "locked in" after initial patterning like in many animal systems, but possesses considerable developmental plasticity due to continuous reliance on mobile transcription factors.

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“…The wooden leg (wol) mutation in the Arabidopsis Histidine Kinase4/CYTOKININ RE-SISTANT1/WOODEN LEG (AHK4/CRE1/WOL) gene results in reduced cell divisions in the root meristem and a dramatic reduction, or absence of, phloem tissues in the root and hypocotyl (Scheres et al, 1994). The AHK4/CRE1/WOL gene encodes a membrane associated two-component histidine kinase (Mahonen et al, 2000) and has been identifi ed as a cytokinin receptor by conferring cytokinin responsiveness to yeast cells, when inserted into an appropriate yeast signal transduction pathway (Inoue et al, 2001). Two closely related proteins, AHK2 and AHK3 have also been identifi ed as cytokinin receptors.…”

Section: Separating Vascular and Ground Tissuementioning

confidence: 99%

Embryogenesis: Pattern Formation from a Single Cell

Capron

Chatfield

Provart

et al. 2009

The Arabidopsis Book

103

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During embryogenesis a single cell gives rise to a functional multicellular organism. In higher plants, as in many other multicellular systems, essential architectural features, such as body axes and major tissue layers are established early in embryogenesis and serve as a positional framework for subsequent pattern elaboration. In Arabidopsis, the apicalbasal axis and the radial pattern of tissues wrapped around it are already recognizable in young embryos of only about a hundred cells in size. This early axial pattern seems to provide a coordinate system for the embryonic initiation of shoot and root. Findings from genetic studies in Arabidopsis are revealing molecular mechanisms underlying the initial establishment of the axial core pattern and its subsequent elaboration into functional shoots and roots. The genetic programs operating in the early embryo organize functional cell patterns rapidly and reproducibly from minimal cell numbers. Understanding their molecular details could therefore greatly expand our ability to generate plant body patterns de novo, with important implications for plant breeding and biotechnology.

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A novel two-component hybrid molecule regulates vascular morphogenesis of the Arabidopsis root

Cited by 521 publications

References 35 publications

Cytokinin-Deficient Transgenic Arabidopsis Plants Show Multiple Developmental Alterations Indicating Opposite Functions of Cytokinins in the Regulation of Shoot and Root Meristem Activity

Cytokinin-Deficient Transgenic Arabidopsis Plants Show Multiple Developmental Alterations Indicating Opposite Functions of Cytokinins in the Regulation of Shoot and Root Meristem Activity

Arabidopsis BIRD Zinc Finger Proteins Jointly Stabilize Tissue Boundaries by Confining the Cell Fate Regulator SHORT-ROOT and Contributing to Fate Specification

Embryogenesis: Pattern Formation from a Single Cell

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