TRAAS , Jan

While many molecular players involved in growth control have been identified in the past decades, it is often unknown how they mechanistically act to induce specific shape changes during development. Plant morphogenesis results from the turgor-induced yielding of the extracellular, load-bearing cell wall. Its mechano-chemical equilibrium...

Au-delà de l'expérimentation in vitro, l'expérimentation sur ordinateur devrait permettre de mieux comprendre les conditions de croissance des plantes.

In a recent paper, Coen et al. [2004] proposed a qualitative framework to study morphogenesis and express the link between genetics and shape development. This paper is an attempt to formalise this approach. It explains, from a mathematical point of view, the decomposition of local growth into the elemental transformations (scaling, anisotropy...

A partir de quelques principes de géométrie, de physique et de biologie, on simule avec réalisme des processus de fonctionnement des plantes, tels que l'éclairement des arbres fruitiers ou la croissance

The shoot apical meristem (SAM) is a small population of stem cells that continuously generates organs and tissues. This review covers our current understanding of organ initiation by the SAM in Arabidopsis thaliana. Meristem function and maintenance involves two major hormones, cytokinins and auxins. Cytokinins appear to play a major role in...

no abstract

Les plantes poussent... ce phénomène, banal en apparence, est en fait le résultat d'un ensemble de processus encore imparfaitement connus et maîtrisés. Pour comprendre la croissance des plantes, gérer l'état de la végétation, contrôler et prévoir sa production, les chercheurs en botanique et en agronomie font depuis quelques années appel à la...

Growth and morphogenesis in plants require controlled transport of the plant hormone auxin. An important participant is the auxin effluxing protein PIN, whose polarized subcellular localization allows it to effectively transport auxin large distances through tissues. The flux-based model, in which auxin flux through a wall stimulates PIN...

The definition of shape in multicellular organisms is a major issue of developmental biology. It is well established that morphogenesis relies on genetic regulation. However, cells, tissues, and organism behaviors are also bound by the laws of physics, which limit the range of possible deformations organisms can undergo but also define what...

Plants continuously generate new organs through the activity of populations of stem cells called meristems. The shoot apical meristem initiates leaves, flowers, and lateral meristems in highly ordered, spiralled, or whorled patterns via a process called phyllotaxis. It is commonly accepted that the active transport of the plant hormone auxin...

The shoot apical meristem (SAM) is at the origin of all the plant above-ground organs (including stems, leaves and flowers) and is a biological object of interest for the understanding of plant morphogenesis. The quantification of tissue growth at a cellular level requires the analysis of 3D microscopic image sequences of developing meristems....

International audience

The link between genetic regulation and the definition of form and size during morphogenesis remains largely an open question in both plant and animal biology. This is partially due to the complexity of the process, involving extensive molecular networks, multiple feedbacks between different scales of organization and physical forces operating...

Quantitative information on growing organs is required to better understand morphogenesis in both plants and animals. However, detailed analyses of growth patterns at cellular resolution have remained elusive. We developed an approach, multiangle image acquisition, three-dimensional reconstruction and cell segmentation-automated lineage...

The active transport of the plant hormone auxin plays a major role in the initiation of organs at the shoot apex. Polar localized membrane proteins of the PIN1 family facilitate this transport, and recent observations suggest that auxin maxima created by these proteins are at the basis of organ initiation. This hypothesis is based on the...

Flower patterning is determined by a complex molecular network but how this network functions remains to be elucidated. Here, we develop an integrative modeling approach that assembles heterogeneous data into a biologically coherent model to allow predictions to be made and inconsistencies among the data to be found. We use this approach to...

To control morphogenesis, molecular regulatory networks have to interfere with the mechanical properties of the indi-vidual cells of developing organs and tissues, but how this is achieved is not well known. We study this issue here in the shoot meristem of higher plants, a group of undifferenti-ated cells where complex changes in growth rates...