CNRS Laboratory of Plant Reproduction and Development

Lyon, France

CNRS Laboratory of Plant Reproduction and Development

Lyon, France
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Jaillais Y.,CNRS Laboratory of Plant Reproduction and Development | Vert G.,French National Center for Scientific Research | Vert G.,Salk Institute for Biological Studies
Nature Cell Biology | Year: 2012

The steroid hormones found in plants, the brassinosteroids, were originally genetically identified about 15 years ago as critical regulators of seedling photomorphogenesis. Two studies now shed light on the molecular mechanisms behind this observation. Brassinosteroids control seedling morphogenesis through direct interaction with master transcriptional regulators downstream of growth-promoting hormones and light signalling. © 2012 Macmillan Publishers Limited. All rights reserved.

Hamant O.,CNRS Laboratory of Plant Reproduction and Development | Hamant O.,University of Lyon
Current Opinion in Plant Biology | Year: 2013

Mechanical forces play an instructing role for many aspects of animal cell biology, such as division, polarity and fate. Although the associated mechanoperception pathways still remain largely elusive in plants, physical cues have long been thought to guide development in parallel to biochemical factors. With the development of new imaging techniques, micromechanics tools and modeling approaches, the role of mechanical signals in plant development is now re-examined and fully integrated with modern cell biology. Using recent examples from the literature, I propose to use a multiscale perspective, from the whole plant down to the cell wall, to fully appreciate the diversity of developmental processes that depend on mechanical signals. Incidentally, this also illustrates how conceptually rich this field is. © 2013 Elsevier Ltd.

Finet C.,Howard Hughes Medical Institute | Jaillais Y.,CNRS Laboratory of Plant Reproduction and Development
Developmental Biology | Year: 2012

Auxin is implicated throughout plant growth and development. Although the effects of this plant hormone have been recognized for more than a century, it is only in the past two decades that light has been shed on the molecular mechanisms that regulate auxin homeostasis, signaling, transport, crosstalk with other hormonal pathways as well as its roles in plant development. These discoveries established a molecular framework to study the role of auxin in land plant evolution. Here, we review recent advances in auxin biology and their implications in both micro- and macro-evolution of plant morphology. By analogy to the term 'hoxology', which refers to the critical role of . HOX genes in metazoan evolution, we propose to introduce the term 'auxology' to take into account the crucial role of auxin in plant evo-devo. © 2012 Elsevier Inc.

Hamant O.,CNRS Laboratory of Plant Reproduction and Development
BMC Biology | Year: 2011

In developmental biology, the accumulation of qualitative phenotypic descriptions has fueled the need for testable parsimonious hypotheses, giving a fresh impetus to quantitative strategies. As an illustration, thanks to the precise quantification of cell growth and microtubule behavior in a study published in BMC Plant Biology, Zhang and collaborators have identified sequential phases of polarized and isotropic growth in puzzle-shaped leaf epidermal cells, thus providing new clues to explore how growth coordination occurs in this tissue. © 2011 Hamant; licensee BioMed Central Ltd.

Hamant O.,CNRS Laboratory of Plant Reproduction and Development | Traas J.,CNRS Laboratory of Plant Reproduction and Development
New Phytologist | Year: 2010

Contents Summary Morphogenesis in living organisms relies on the integration of both biochemical and mechanical signals. During the last decade, attention has been mainly focused on the role of biochemical signals in patterning and morphogenesis, leaving the contribution of mechanics largely unexplored. Fortunately, the development of new tools and approaches has made it possible to re-examine these processes. In plants, shape is defined by two local variables: growth rate and growth direction. At the level of the cell, these variables depend on both the cell wall and turgor pressure. Multidisciplinary approaches have been used to understand how these cellular processes are integrated in the growing tissues. These include quantitative live imaging to measure growth rate and direction in tissues with cellular resolution. In parallel, stress patterns have been artificially modified and their impact on strain and cell behavior been analysed. Importantly, computational models based on analogies with continuum mechanics systems have been useful in interpreting the results. In this review, we will discuss these issues focusing on the shoot apical meristem, a population of stem cells that is responsible for the initiation of the aerial organs of the plant. © 2009 New Phytologist.

Boudaoud A.,CNRS Laboratory of Plant Reproduction and Development
Trends in Plant Science | Year: 2010

Plants are under tremendous mechanical forces generated by turgor pressure. How do these forces mediate growth and development? In order to answer this question, it is necessary to understand the mechanics of growth and morphogenesis. In this 'mathless' tutorial, the concepts of strain, mechanical stress and buckling are reviewed and illustrated with recent work on leaf shape, on leaf vasculature, and on organogenesis at the shoot apical meristem. © 2010 Elsevier Ltd. All rights reserved.

Vernoux T.,CNRS Laboratory of Plant Reproduction and Development
Cold Spring Harbor perspectives in biology | Year: 2010

Plants continuously generate new tissues and organs through the activity of populations of undifferentiated stem cells, called meristems. Here, we discuss the so-called shoot apical meristem (SAM), which generates all the aerial parts of the plant. It has been known for many years that auxin plays a central role in the functioning of this meristem. Auxin is not homogeneously distributed at the SAM and it is thought that this distribution is interpreted in terms of differential gene expression and patterned growth. In this context, auxin transporters of the PIN and AUX families, creating auxin maxima and minima, are crucial regulators. However, auxin transport is not the only factor involved. Auxin biosynthesis genes also show specific, patterned activities, and local auxin synthesis appears to be essential for meristem function as well. In addition, auxin perception and signal transduction defining the competence of cells to react to auxin, add further complexity to the issue. To unravel this intricate signaling network at the SAM, systems biology approaches, involving not only molecular genetics but also live imaging and computational modeling, have become increasingly important.

Das P.,CNRS Laboratory of Plant Reproduction and Development
Current Opinion in Genetics and Development | Year: 2011

The growth of tissues, organs or organisms derives from the coordinated activities of complex genetic regulatory networks. In addition to its molecular underpinnings, growth also generally involves significant changes in geometry. To fully understand morphogenesis in its molecular and physical contexts the development of an interdisciplinary approach is required associating biology, mathematics, and physics, which held together by computer science. Growth quantitation and digital simulations have been developed to generate and test the plausibilities of complex hypotheses. Increasingly, real-time live imaging protocols are becoming an essential part of this process. In this review, I discuss the evolution of imaging techniques in plant developmental biology and briefly examine the different ways in which these studies have shed light on growth and morphogenesis in plants. © 2011 Elsevier Ltd.

Sassi M.,CNRS Laboratory of Plant Reproduction and Development | Vernoux T.,CNRS Laboratory of Plant Reproduction and Development
Journal of Experimental Botany | Year: 2013

Plants continuously generate new tissues and organs throughout their life cycle, due to the activity of populations of specialized tissues containing stem cells called meristems. The shoot apical meristem (SAM) generates all the aboveground organs of the plant, including leaves and flowers, and plays a key role in plant survival and reproduction. Organ production at the SAM occurs following precise spatio-temporal patterns known as phyllotaxis. Because of the regularity of these patterns, phyllotaxis has been the subject of investigations from biologists, physicists, and mathematicians for several centuries. Both experimental and theoretical works have led to the idea that phyllotaxis results from a self-organizing process in the meristem via long-distance interactions between organs. In recent years, the phytohormone auxin has emerged not only as the central regulator of organogenesis at the SAM, but also as a major determinant of the self-organizing properties of phyllotaxis. Here, we discuss both the experimental and theoretical evidence for the implication of auxin in the control of organogenesis and self-organization of the SAM. We highlight how several layers of control acting at different scales contribute together to the function of the auxin signal in SAM dynamics. We also indicate a role for mechanical forces in the development of the SAM, supported by recent interdisciplinary studies. © 2013 © The Author [2013]. Published by Oxford University Press [on behalf of the Society for Experimental Biology]. All rights reserved.

Traas J.,CNRS Laboratory of Plant Reproduction and Development
Development (Cambridge) | Year: 2013

The precise arrangement of plant organs, also called phyllotaxis, has fascinated scientists from multiple disciplines. Whereas early work focused on morphological observations of phyllotaxis, recent findings have started to reveal the mechanisms behind this process, showing how molecular regulation and biochemical gradients interact with physical components to generate such precise patterns of growth. Here, I review new insights into the regulation of phyllotactic patterning and provide an overview of the various factors that can drive these robust growth patterns. © 2013. Published by The Company of Biologists Ltd.

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