Patrick Laufs

French National Institute for Agriculture, Food, and Environment (INRAE) | INRAE · Institut Jean-Pierre Bourgin

Hydathodes are small organs found on the leaf margins of vascular plants which release excess xylem sap through a process called guttation. While previous studies have hinted at additional functions of hydathode in metabolite transport or auxin metabolism, experimental support is limited. We conducted comprehensive transcriptomic, metabolomic and p...

Genetic screens are powerful tools for biological research and are one of the reasons for the success of the thale cress Arabidopsis thaliana as a research model. Here, we describe the whole‐genome sequencing of 871 Arabidopsis lines from the Homozygous EMS Mutant (HEM) collection as a novel resource for forward and reverse genetics. With an averag...

How tissue-level information encoded by fields of regulatory gene activity is translated into the patterns of cell polarity and growth that generate the diverse shapes of different species remains poorly understood. Here, we investigate this problem in the case of leaf shape differences between Arabidopsis thaliana , which has simple leaves, and it...

Gene expression analysis is essential for understanding the mechanisms involved in plant development. Here, we developed M2WISH, a protocol based on M icro W ave treatment for W holemount mRNA I n S itu H ybridization in Arabidopsis. By permeabilizing tissues without damaging cellular organization this protocol results in high and homogeneous hybri...

Gene expression analysis is essential for understanding the mechanisms involved in plant development. Here, we developed M2WISH, a protocol based on MicroWave treatment for Wholemount mRNA In Situ Hybridization in Arabidopsis. By permeabilizing tissues without damaging cellular organisation this protocol results in high and homogeneous hybridizatio...

Genetic screens are powerful tools for biological research and are one of the reasons for the success of the thale cress Arabidopsis thaliana as a model species. Here, we describe the whole-genome sequencing of 871 Arabidopsis lines from the Homozygous EMS Mutant (HEM) collection as a novel resource for forward and reverse genetics. With an average...

Robustness is pervasive throughout biological systems, enabling them to maintain persistent outputs despite perturbations in their components. Here, we reveal a novel mechanism contributing to leaf morphology robustness in the face of genetic perturbations. In Arabidopsis, leaf shape is established during early development through the quantitative...

Plant development and reproduction are complex processes during which an individual fulfills its life cycle, starting from germination and the elaboration of new organs and growth, leading to the formation of reproductive structures and ultimately terminating in the production of the next generation. These mechanisms are the result of a long evolut...

Hydathodes are small organs located on the leaf margins of all vascular plants. They release excess xylem sap through guttation when stomata are closed or when the humidity level is high. Many promoter analyses have suggested other hydathode functions in metabolite transport and auxin metabolism, but experimental demonstration is still lacking. Her...

LEAFY plant-specific transcription factors, which are key regulators of flower meristem identity and floral patterning, also contribute to meristem activity. Notably, in some legumes, LFY orthologs such as Medicago truncatula SINGLE LEAFLET (SGL1) are essential in maintaining an undifferentiated and proliferating fate required for leaflet formation...

In plants, stem cells are embedded in structures called meristems. Meristems can be formed either during embryogenesis or during the plant’s life such as, for instance, axillary meristems. While the regulation of the stem cell population in an established meristem is well described, how it is initiated in newly formed meristems is less well underst...

Stem cells play important roles in animal and plant biology, as they sustain morphogenesis and tissue replenishment following aging or injury. In plants, stem cells are embedded in multicellular structures called meristems. The formation of new meristems is essential for the plastic expansion of the highly branched shoot and root systems. In partic...

Bellenot et al. introduce hydathodes, an oft-overlooked plant organ that acts as a pressure valve to expel excess guttation sap at the leaf margin, typically visible at dawn.

Boundary domains delimit and organize organ growth throughout plant development almost relentlessly building plant architecture and morphogenesis. Boundary domains display reduced growth and orchestrate development of adjacent tissues in a non-cell autonomous manner. How these two functions are achieved remains elusive despite the identification of...

Plant aerial development relies on meristem activity which ensures main body plant axis development during plant life. While the shoot apical meristem (SAM) formed in the embryo only contributes to the main stem, the branched structure observed in many plants relies on axillary meristems (AMs) formed post-embryonically. These AMs initiate from a fe...

Stem cells play important roles in animal and plant biology as they sustain morphogenesis and tissue replenishment following aging or injuries. In plants, stem cells are embedded in multicellular structures called meristems and the formation of new meristems is essential for the plastic expansion of the highly branched shoot and root systems. In pa...

Shoot branching is highly dependent on environmental factors. While many species show some light dependence for branching, the rosebush shows a strict requirement for light to allow branching, making this species an excellent model to further understand how light impinges on branching. Here, in the first part, we provide a review of the current und...

Plant organ morphogenesis spans several orders of magnitude in time and space. Because of limitations in live-imaging, analysing whole organ growth from initiation to mature stages typically rely on static data sampled from different timepoints and individuals. We introduce a new model-based strategy for dating organs and for reconstructing morphog...

Boundary domains delimit and organize organ growth throughout plant development almost relentlessly building plant architecture and morphogenesis. Boundary domains display reduced growth and orchestrate development of adjacent tissues in a non-cell autonomous manner. How these two functions are achieved remains elusive despite the identification of...

Intégrant les derniers acquis de la biologie cellulaire et de la génétique moléculaire, cette quatrième édition, entièrement corrigée, offre un panorama de l’ensemble de la biologie végétale enseignée dans les premières années d’études supérieures (Licence, M1, Pharmacie, classes préparatoires, IUT,). Ce volume traite des aspects physiologiques et...

Hydathodes are organs found on aerial parts of a wide range of plant species that provide almost direct access for several pathogenic microbes to the plant vascular system. Hydathodes are better known as the site of guttation, which is the release of droplets of plant apoplastic fluid to the outer leaf surface. Because these organs are only describ...

Cell division and growth are the major cellular mechanisms that determine the size and shape of plant organs such as leaves. How these mechanisms are orchestrated during leaf morphogenesis remains unknown. Our objective here is to quantify 3D cell parameters during leaf development.

Analyzing gene expression patterns over the tissue of an organ during growth is a means to decipher the biological mechanisms that control its shaping. For this, the organ is often sampled and imaged in different individuals at different developmental stages. However, estimating a continuous developmental process from a discrete dataset is an arduo...

Boundary domains play important roles during morphogenesis in plants and animals, but how they contribute to patterning and growth coordination in plants is not understood. The CUC genes determine the boundary domains in the aerial part of the plants and, in particular, they have a conserved role in regulating leaf complexity across Angiosperms. He...

CUC2 mRNA level quantification in wild type, cuc2-1 and cuc2-3. Real-time RT-PCR quantifications of CUC2 mRNA levels in the wild type (WT), cuc2-1 and cuc2-3 mutants. Total RNAs were extracted from 2 week-old plants dissected to remove all leaves and CUC2 mRNA levels were normalized by EF1α and qREF. Each point represents a biological replicate. (P...

CUC2i line characterization, related to Fig 2. (A) Prolonged CUC2i induction restores multiple teeth formation. Leaf silhouettes from leaves of comparable rank from wild type (WT), cuc2-1 and CUC2i plants induced by ethanol for 5x8h and observed 9 days after induction. (B) Only small leaf primordia (< ∼1200μm) form teeth following CUC2i induction....

Details of the methods used to compare CUC2 levels with tooth morphogenesis related to Fig 3. (A,C) Tooth height evolution along blade length in different genotypes. Data are individual measures and a linear regression for each genotype is shown (for all genotypes r > 0.93). The regression slope is the Tooth growth rate in Fig 3. (B,D) Quantificati...

Detailed characterization of the auxin response during CUC2-induced tooth development, related to Fig 6. (A-B) Dynamics of DII-VENUS (A), mDII-VENUS (B) after an 8h ethanol induction. Time following the start of induction is indicated. (A) 48h after induction, arrowhead shows local DII-VENUS degradation, reflecting increased early auxin signaling....

Spreadsheet with the numerical data underlying graphs from the main figures. (XLSX)

Detailed characterization of KLUH as a functionnal relay for CUC2-triggered toth outgrowth, related to Fig 7. (A) Relative localization of RFP-CUC2 protein and expression of a pKLUH:GFP reporter after an 8h ethanol induction. pKLUH-GFP is observed in the center of the RFP-CUC2 domain. (B) Sinus angle dynamics after an 8h ethanol induction in a CUC2...

Contribution of the strong local auxin response to the dynamics of pCUC3:CFP, pKLUH:GFP and RFP-CUC2 expression, related to Fig 9. (A) RFP-CUC2 distribution and pDR5:VENUS expression pattern observed 52h after the start of a 2x8h ethanol induction followed by NPA application @0h and @24h relative to induction. For the RFP-CUC2 and pDR5:VENUS channe...

Primers used for real-time PCR analysis. (PDF)

Spreadsheet with the numerical data underlying graphs from the supporting information figures. (XLSX)

Detailed characterization of CUC3 as a local functional relay for CUC2-triggered toth outgrowth, related to Fig 4. (A) Relative localization of RFP-CUC2 protein and expression of a pCUC3:CFP reporter after an 8h ethanol induction. The time following the start of induction is shown on the overlay panels. Note coexpression of RFP-CUC2 and pCUC3:CFP i...

Acquisition parameters for confocal reporter imaging. (PDF)

Hydathodes are organs found on aerial parts of a wide range of plant species that provide almost direct access for several pathogenic microbes to the plant vascular system. Hydathodes are better known as the site of guttation, which is the release of droplets of plant apoplastic fluid to the outer leaf surface. Because these organs are only describ...

Heterogeneity is observed at all levels in living organisms, but its role during the development of an individual is not well understood. Heterogeneity has either to be limited to ensure robust development or can be an actor of the biological processes leading to reproducible development. Here we review the sources of heterogeneity in plants, stres...

Leaves arise from groups of undifferentiated cells as small primordia that go through overlapping phases of morphogenesis, growth and differentiation. These phases are genetically controlled and modulated by environmental cues to generate a stereotyped, yet plastic, mature organ. Over the past couple of decades, studies have revealed that hormonal...

The CUP-SHAPED COTYLEDON (CUC) transcription factors control plant boundary formation, thus allowing the emergence of novel growth axes. While the developmental roles of the CUC genes in different organs and across species are well characterized, upstream and downstream events that contribute to their function are still poorly understood. To identi...

Morphogenesis is a complex process that integrates several mechanisms from the molecular to the organ scales. In plants, division and growth are the two fundamental cellular mechanisms that drive morphogenesis. However, little is known about how these mechanisms are coordinated to establish functional tissue structure. A fundamental bottleneck is t...

Development in plants is a continuous process during which new tissues and organs are formed all along its life cycle. Development involves the coordination of both time and space of complex cellular processes such as proliferation, expansion and differentiation following endogenous programmes and in response to environmental signals. Since their d...

A major challenge in morphometrics is to analyse complex biological shapes formed by structures at different scales. Leaves exemplify this challenge as they combine differences in their overall shape with smaller shape variations at their margin leading to lobes or teeth. Current methods based on contour or on landmarks analysis are successful in q...

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Summary of the number of replicates for each mechanical test. DOI: http://dx.doi.org/10.7554/eLife.07811.031

The role of mechanical signals in cell identity determination remains poorly explored in tissues. Furthermore, because mechanical stress is widespread, mechanical signals are difficult to uncouple from biochemical-based transduction pathways. Here we focus on the homeobox gene SHOOT MERISTEMLESS (STM), a master regulator and marker of meristematic...

Two interrelated problems in biology are understanding the regulatory logic and predictability of morphological evolution. Here, we studied these problems by comparing Arabidopsis thaliana, which has simple leaves, and its relative, Cardamine hirsuta, which has dissected leaves comprising leaflets. By transferring genes between the two species, we...

The no apical meristem/cup-shaped cotyledon (NAM/CUC3) transcription factors, which include the Arabidopsis CUC proteins, are evolutionary conserved factors that play essential roles in the establishment and function of boundaries, small domains that act both as frontiers and morphogenesis-organizing centers. In this chapter, we will review structu...

The evolution of plant reproductive strategies has led to a remarkable diversity of structures, especially within the flower, a structure characteristic of the angiosperms. In flowering plants, sexual reproduction depends notably on the development of the gynoecium that produces and protects the ovules. In Arabidopsis thaliana, ovule initiation is...

Summary Unlike animal development, plant development is an ongoing process. In plants, vegetative development is highly repetitive, producing the same or similar structures over and over again. Plant grow continue indefinitely, a phenomenon known as indeterminate growth. Increase in length at the apex of shoot and root of plants is determined by m...

Flower architecture mutants provide a unique opportunity to address the genetic origin of flower diversity. Here we study a naturally occurring floral dimorphism in Nigella damascena (Ranunculaceae), involving the replacement of the petals by numerous sepal-like and chimerical sepal-stamen organs. We performed a comparative study of floral morpholo...

Leaves show a wide range of shapes that results from the combinatory variations of two main parameters: the relative duration of the morphogenetic phase and the pattern of dissection of the leaf margin. To further understand the mechanisms controlling leaf shape, we have studied the interactions between several loci leading to increased dissection...

Patterning in plants requires defining boundary domains that separate and organize the development of the neighboring organs. Two papers now show how the interplay between brassinosteroid phytohormones and frontier genes contributes to boundary formation in plants.

Like most animals, plants also sleep at night, or at least some of them. For instance, the flowers of many species, such as crocus, tulip, and morning glory, are open during the day or part of the day and close at night. Based on such observations, in 1751, the Swedish botanist Carl von Linne suggested combining several plant species in which the f...

Plant leaves and flowers are positioned along the stem in a regular pattern. This pattern, which is referred to as phyllotaxis, is generated through the precise emergence of lateral organs and is controlled by gradients of the plant hormone auxin. This pattern is actively maintained during stem growth through controlled cell proliferation and elong...

How are the regular patterns of organs established along a plant stem and how are the transitions between different patterns regulated? Now genes of the PLETHORA family have been shown to modulate these transitions by fine-tuning the mechanisms of polar transport of auxin, a key effector of organogenesis.

CUP-SHAPED COTYLEDON2 (CUC2) and the interacting microRNA miR164 regulate leaf margin dissection. Here, we further investigate the evolution and the specific roles of the CUC1 to CUC3 genes during Arabidopsis thaliana leaf serration. We show that CUC2 is essential for dissecting the leaves of a wide range of lobed/serrated Arabidopsis lines. Inacti...

Biological shapes are often produced by the iterative generation of repeated units. The mechanistic basis of such iteration is an area of intense investigation. Leaf development in the model plant Arabidopsis is one such example where the repeated generation of leaf margin protrusions, termed serrations, is a key feature of final shape. However, th...

In order to understand how the morphology of plant species has diversified over time, it is necessary to decipher how the underlying developmental programs have evolved. The regulatory network controlling shoot meristem activity is likely to have played an important role in morphological diversification and useful insights can be gained by comparin...

Leaves, which play an essential role in plant photosynthesis, share common features such as being flat structures, but also show an impressive variability in their sizes and shapes. Following its initiation in the meristems, leaf development is patterned along three polarization axes to establish its basic architecture. This process is further comp...

Leaf development entails the transition from a small group of undifferentiated cells to a structure of defined size and shape, highly organized into different cell types with specialized functions. During this developmental sequence, patterning, growth, and differentiation have to be tightly coordinated by intricate regulatory networks in which sma...

Formation of dissected compound leaves involves the transient maintenance of an indeterminate environment and the generation of new growth axes that will generate leaflets. Recent work has revealed additional multi-layered mechanisms controlling the activities of the KNOXI homeodomains factors that play a prominent role in the control of indetermin...

A recent report shows that cells in the Arabidopsis apical meristem orientate their cortical microtubules along mechanical stress patterns generated during tissue morphogenesis. This in turn is expected to influence the mechanical properties of the cell via the modification of the cortical microtubule network and the cell wall. This feedback loop c...

Diversity in leaf shape is produced by alterations of the margin: for example, deep dissection leads to leaflet formation and less-pronounced incision results in serrations or lobes. By combining gene silencing and mutant analyses in four distantly related eudicot species, we show that reducing the function of NAM/CUC boundary genes (NO APICAL MERI...

Plant organs are produced from meristems in a characteristic pattern. This pattern, referred to as phyllotaxis, is thought to be generated by local gradients of an information molecule, auxin. Some studies propose a key role for the mechanical properties of the cell walls in the control of organ outgrowth. A major cell-wall component is the linear...