Anja Geitmann

Anja Geitmann
McGill University | McGill · Department of Plant Science

PhD

About

179
Publications
31,812
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6,184
Citations
Additional affiliations
September 2015 - May 2020
McGill University
Position
  • Professor (Full)
June 2001 - August 2016
Université de Montréal
Position
  • Professor (Full)
June 2001 - August 2016
Université de Montréal
Position
  • Professor (Full)

Publications

Publications (179)
Article
Large scale phenotyping of tip growing cells such as pollen tubes has hitherto been limited to very crude parameters such as germination percentage and velocity of growth. To enable efficient and high throughput execution of more sophisticated assays, an experimental platform was developed based on microfluidic and MEMS (microelectromechanical syst...
Article
Full-text available
Pollen tubes are tip growing plant cells that display oscillatory growth behavior. It has been demonstrated experimentally that the reduction of the average pollen tube growth rate through elevated extracellular calcium or borate concentrations coincides with a greater amplitude of the growth rate oscillation and a lower oscillation frequency. We p...
Article
Cellular growth in plant, fungal and bacterial cells is based on the mechanical deformation of the cellular envelope by the hydrostatic turgor pressure. Shape generation is therefore a mechanical problem whose biological control is poorly understood. The pollen tube is an attractive model system for the investigation of the growth process in walled...
Chapter
The plant cell wall comprises various types of macromolecules whose abundance and spatial distribution change dynamically and are crucial for plant architecture. High-resolution live cell imaging of plant cell wall components is, therefore, a powerful tool for plant cell biology and plant developmental biology. To acquire suitable data, the experim...
Preprint
Mechanistic studies of animal and plant motion often focus on the fundamental units of biological actuation: individual motor cells. Recent advances spanning the fields of muscle physiology and biomimetic actuation, however, reveal that important mechanical behaviors also arise at higher levels of organization, driven by the interplay of motor cell...
Article
Full-text available
Cannabis has been legalized for recreational use in several countries and medical use is authorized in an expanding list of countries; markets are growing internationally, causing an increase in demand for high quality products with well-defined properties. The key compounds of Cannabis plants are cannabinoids, which are produced by stalked glandul...
Article
Full-text available
Mechanoperception, the ability to perceive and respond to mechanical stimuli, is a common and fundamental property of all forms of life. Vascular plants such as Mimosa pudica use this function to protect themselves against herbivory. The mechanical stimulus caused by a landing insect triggers a rapid closing of the leaflets that drives the potentia...
Article
Full-text available
Many plant processes occur in the context of and in interaction with a surrounding matrix such as soil (e.g. root growth and root–microbe interactions) or surrounding tissues (e.g. pollen tube growth through the pistil), making it difficult to study them with high-resolution optical microscopy. Over the past decade, microfabrication techniques have...
Article
The plant cell wall is an extracellular matrix that envelopes cells, gives them structure and shape, constitutes the interface with symbionts, and defends plants against external biotic and abiotic stress factors. The assembly of this matrix is regulated and mediated by the cytoskeleton. Cytoskeletal elements define where new cell wall material is...
Article
Full-text available
In an actively growing scalp hair, the cells proliferating at the basal zone of the hair follicle commence a journey of approximately 4 mm in two weeks before emerging from the scalp surface as a strong rigid fiber. This maturation process of the nascent hair fiber involves many biological, biochemical and biomechanical factors. While we have a ric...
Article
Academic travel has a substantial carbon footprint. The ongoing pandemic has propelled the development and adoption of technologies for online delivery of seminars and remote attendance at scientific conferences. This should not lead to the complete elimination of in-person events, but the scientific community must seize the opportunity to permanen...
Chapter
Successful fertilization and seed set require the pollen tube to grow through several tissues, to change its growth orientation by responding to directional cues, and to ultimately reach the embryo sac and deliver the paternal genetic material. The ability to respond to external directional cues is, therefore, a pivotal feature of pollen tube behav...
Chapter
Live cell imaging at high resolution of pollen tubes growing in vitro requires an experimental setup that maintains the elongated cells in a single optical plane and allows for controlled exchange of growth medium. As a low-cost alternative to lithography-based microfluidics, we developed a silicone-based spacer system that allows introducing spati...
Data
Movie 2. Growing Camellia japonica pollen tube labeled with COS488 in liquid medium. The video is composed of maximum projection of z-stacks acquired over 20 time points with 1-min intervals. The time course experiment was performed using a Zeiss LSM 710 confocal microscope (doi.org/10.1111/jmi.12895).
Chapter
Tensile testing is widely used to evaluate the mechanical properties of biological materials including soft primary plant tissues. Commercially available platforms for tensile testing are often expensive and limited in customizability. In this chapter, we provide a guide for the assembly and use of a simple and low-cost micromechanical testing appa...
Article
Full-text available
Plant cell walls constitute the extracellular matrix surrounding plant cells and are composed mainly of polysaccharides. The chemical makeup of the primary plant cell wall, and specifically, the abundance, localization, and arrangement of the constituting polysaccharides are intimately linked with growth, morphogenesis, and differentiation in plant...
Data
Movie 1. Growing Camellia japonica pollen tube stained with 1 µg/ml calcofluor white in liquid medium. The video is composed of maximum projection of z-stacks acquired over 20 time points with 1-min intervals. The right panel shows the bright field channel. The time course experiment was performed using a Zeiss spinning disk microscope (doi.org/10....
Article
To reach the female gametophyte, growing pollen tubes must penetrate different tissues within the pistil, the female reproductive organ of a flower. Past research has identified various chemotropic cues that guide pollen tubes through the transmitting tract of the pistil, which represents the longest segment of its growth path. In addition, physica...
Article
The carnivorous plant Utricularia gibba forms cup-shaped leaflets to capture prey. Whitewoods et al. (2020) use computational modeling to simulate the formation of the trap's 3D geometry. Directional expansion of the young leaflet is proposed to be a crucial morphogenetic driver, pointing at a fundamental principle of plant development.
Cover Page
Full-text available
Related: Modeling the nonlinear elastic behavior of plant epidermis https://www.nrcresearchpress.com/doi/10.1139/cjb-2019-0058#.Xiy5sCNOk2y
Book
This volume explores a collection of experimental techniques used to investigate different aspects of pollen development and function, including its role in reaching the ovule and delivering the two sperm cells. The techniques discussed range from basic methodology to cultivate pollen in vitro to the sophisticated experiments involving micromanipul...
Cover Page
Full-text available
On the Cover: The leaf epidermis manifests some fascinating cell shapes. This rendering is based on a scanning electron micrograph of the epidermis of an Arabidopsis cotyledon and illustrates pairs of kidney-shaped guard cells (red) interspersed between pavement cells which form wavy shapes that interlock into a jigsaw puzzle pattern. The wavy cell...
Article
Full-text available
Pavement cells form wavy interlocking patterns in the leaf epidermis of many plants. We use computational mechanics to simulate the morphogenetic process based on microtubule organization and cell wall chemistry. Based on the in silico simulations and experimental evidence, we suggest that a multistep process underlies the morphogenesis of pavement...
Cover Page
Full-text available
On the cover: The image depicts a finite element model of Arabidopsis thaliana cotyledon epidermis. The model simulates the turgor-driven deformation of the cell wall and predicts the mechanics underlying the generation of wavy cell shapes from simple geometries. The simulations predict that wave expansion is driven by a feedback loop based on mech...
Article
Simple plant cell morphologies, such as cylindrical shoot cells, are determined by the extensibility pattern of the primary cell wall, which is thought to be largely dominated by cellulose microfibrils, but the mechanism leading to more complex shapes, such as the interdigitated patterns in the epidermis of many eudicotyledon leaves, is much less w...
Article
Cell growth and organ development in plants are often correlated with the tensile behavior of the primary cell wall. To understand the mechanical behavior of plant material, various mechanical testing techniques have been employed, such as tensile testing of excised tissue samples. The onion (Allium cepa) epidermis has emerged as a model system for...
Cover Page
Full-text available
Cover illustration: Artistic rendering of a finite element model simulating the microindentation of a leaf epidermis. Image by Amir J Bidhendi and Anja Geitmann.
Article
Full-text available
Living beings obey physical laws, and this applies at all scales of the organism, from the interaction of the whole organism with its environment to subcellular processes. Biomechanics research enhances our understanding of the manner in which biological organisms cope with and exploit physical principles and how the functional design of cells, tis...
Article
The primary plant cell wall is a dynamically regulated composite material of multiple biopolymers that forms a scaffold enclosing the plant cells. The mechanochemical make-up of this polymer network regulates growth, morphogenesis, and stability at the cell and tissue scales. To understand the dynamics of cell wall mechanics, and how it correlates...
Article
Free access: https://authors.elsevier.com/a/1ZJmg5Sx5gfpml ----------------- Summary: Morphogenesis of wavy epidermal pavement cells in plants has fascinated researchers for decades. A mechanical mechanism had been proposed in which the anticlinal cell walls, forming the in-plane cell borders, feature contiguous stiff and soft zones that generate...
Preprint
Full-text available
Plant cell morphogenesis is governed by the mechanical properties of the cell wall and the resulting cell shape is intimately related to the respective specific function. Pavement cells covering the surface of plant leaves form wavy interlocking patterns in many plants. We use computational mechanics to simulate the morphogenetic process based on e...
Article
Polarized cell growth in plants is maintained under the strict control and exquisitely choregraphed balance of exocytic and endocytic membrane trafficking. The pollen tube has become a model system for rapid polar growth in which delivery of cell wall material and membrane recycling are controlled by membrane trafficking. Endocytosis plays an impor...
Article
FRAP Experiments Show Pectate Lyases Promote Pollen Germination and Lubricate the Path of the Pollen Tube in Arabidopsis thaliana. - Volume 24 Supplement - Youssef Chebli, Anja Geitmann
Article
The pollen tube is a tip growing cell that is able to invade plant tissues in order to accomplish its function — the delivery of sperm cells to the ovule. The pistillar tissues through which the tube has to elongate represent a formidable mechanical obstacle, but it is unknown how much force the growing tube is able to exert, or how mechanical impe...
Chapter
The primary cell wall controls plant growth and morphogenesis but also determines the structural resilience of nonwoody plant organs. The predominant mechanical role of the primary cell wall lies in its ability to resist or conform to tensile forces. Assessing the tensile properties of the cell wall, therefore, is fundamental for both biomechanics...
Book
This book provides important insights into the operating principles of plants by highlighting the relationship between structure and function. It describes the quantitative determination of structural and mechanical parameters, such as the material properties of a tissue, in correlation with specific features, such as the ability of the tissue to c...
Article
The detachment of plant organs is highly choreographed, requiring the enzymatic dissolution of the middle lamella between cell layers at the base of the detaching organ. Now, Lee et al. demonstrate that abscission efficiency and plant health rely on the spatial confinement of enzymatic activity and mechanical features that ensure a smooth separatio...
Article
The pollen tube features particular traits that can only be understood when integrating cell biological with cell mechanical concepts. Firstly, regular temporal variations in the growth rate are governed by a feedback mechanism thought to involve mechanosensitive ion channels. Secondly, the tube uses invasive growth to penetrate the flower tissues...
Article
(Full-text Open Access! www.plantphysiol.org/content/176/1/41): Plant cells come in a striking variety of different shapes. Shape formation in plant cells is controlled through modulation of the cell wall polymers and propelled by the turgor pressure. Understanding the shaping aspects of plant cells requires knowledge of the molecular players and...
Article
Full-text available
Responses of cells to mechanical stress are thought to be critical in coordinating growth and development. Consistent with this idea, mechanically activated channels play important roles in animal development. For example, the PIEZO1 channel controls cell division and epithelial layer integrity and is necessary for vascular development in mammals....
Article
The fungal pathogen Candida albicans differentiates between yeast, hyphae and pseudohyphae in order to enhance survival in the human host. Environmental cues induce hyphal development and expression of hyphal-specific genes. Filaments also result from yeast cell cycle arrest, but the nature of these cells and their mechanisms of formation are less...
Chapter
The control of cellular growth in pollen tubes occurs through the fine-tuning of intracellular transport and secretion processes. This does not only apply to the basic genesis of the cylindrical cell through polar expansion but also to the pollen tube’s specialized skills including its capacity to respond to directional guidance cues and its abilit...
Chapter
Experimentation on pollen tubes has benefited greatly from recent technological developments in the fields of microfluidics and microelectromechanical systems (MEMS). Various design strategies have been developed to expose in vitro growing pollen tubes to a range of experimental assays with the aim to study their behavior and their mechanical prope...
Article
Full-text available
Cell division in plant cells requires the deposition of a new cell wall between the two daughter cells. The assembly of this plate requires coordinated movement of cargo-vesicles whose size is below the diffraction limited resolution of the optical microscope. We combined high spatial and temporal resolution confocal laser scanning microscopy with...
Article
Cell and organ morphogenesis in plants are regulated by the chemical structure and mechanical properties of the extracellular matrix, the cell wall. The two primary load bearing components in the plant cell wall, the pectin matrix and the cellulose/xyloglucan network, are constantly remodelled to generate the morphological changes required during p...
Article
In plant tissues, cells are glued to each other by a pectic polysaccharide rich material known as middle lamella (ML). Along with many biological functions, the ML plays a crucial role in maintaining the structural integrity of plant tissues and organs, as it prevents the cells from separating or sliding against each other. The macromolecular organ...
Chapter
Cell biological experimentation has benefitted from the development of microdevices based on microfluidics and MEMS (microelectromechanical systems) technology. These devices exploit the possibility to create microscopic 3D structures that can be used to manipulate single cells. Furthermore, microdevices can be used to miniaturize laboratory functi...
Article
Plant actuators move organs, allowing the plant to respond to environmental cues or perform other mechanical tasks. In Cardamine hursuta the dispersal of seeds is accomplished by explosive opening of the fruit. The biomechanical mechanism relies on a complex interplay between turgor regulation and cell wall mechanical properties.
Article
Full-text available
Pollen tubes are polarly growing plant cells that are able to rapidly respond to a combination of chemical, mechanical, and electrical cues. This behavioural feature allows them to invade the flower pistil and deliver the sperm cells in highly targeted manner to receptive ovules in order to accomplish fertilization. How signals are perceived and pr...
Article
Free full-text article: https://academic.oup.com/jxb/article-lookup/doi/10.1093/jxb/erv535 Regulation of the mechanical properties of the cell wall is a key parameter used by plants to control the growth behavior of individual cells and tissues. Modulation of the mechanical properties occurs through the control of the biochemical composition and t...
Article
Intracellular transport in plant cells occurs on microtubular and actin arrays. Cytoplasmic streaming, the rapid motion of plant cell organelles, is mostly driven by an actin- myosin mechanism, whereas specialized functions, such as the transport of large cargo or the assembly of a new cell wall during cell division, are performed by the microtubul...
Article
Full-text available
div class="title">Mechanics of Interdigitating Morphogenesis in Pavement Cells - Volume 21 Issue S3 - Amirhossein Jafari Bidhendi, Bara Altartouri, Anja Geitmann
Article
The constant force of gravity plays a primordial role in the ontogeny of all living organisms. Plants, for example, develop their roots and shoots in accordance with the direction of the gravitational vector. Any change in the magnitude and/or the direction of gravity has an important impact on the development of tissues and cells. In order to unde...
Article
The tool delivering the sperm cells in the flowering plants, the pollen tube, has to invade multiple tissues to reach its target within the pistil, the female gametophyte. To accomplish this task the rapidly growing tube must perceive the geometry and mechanical consistency of the growth substrate as well as directional cues guiding it towards the...
Article
Full-text available
Ca(2+) waves and oscillation are key signalling elements during the fertilization process of animals, and are involved, for example, in egg activation. In the unique double fertilization process in flowering plants, both the egg cell and the neighbouring central cell fuse with a sperm cell each. Here we succeeded in imaging cytosolic Ca(2+) in thes...
Article
Full-text available
Pollen tube, the fastest tip growing plant cell, plays essential role in life cycle of flowering plants. It is extremely sensitive to external cues and this makes it as a suitable cellular model for characterizing the cell response to the influence of various signals involved in cellular growth metabolism. For in-vitro study of pollen tube growth,...
Article
The pollen tube is the most rapidly growing cell in the plant kingdom and has the function to deliver the sperm cells for fertilization. The growing tip region of the cell behaves in chemotropic manner to respond to the guidance cues emitted by the pistil and the female gametophyte, but how it perceives and responds to these directional triggers is...
Article
Pollen tubes are polarly growing plant cells that are able to rapidly respond to a combination of chemical, mechanical, and electrical cues. This behavioural feature allows them to invade the flower pistil and deliver the sperm cells in highly targeted manner to receptive ovules in order to accomplish fertilization. How signals are perceived and pr...
Article
A major limitation in the study of pollen tube growth has been the difficulty in providing an in vitro testing microenvironment that physically resembles the in vivo conditions. Here we describe the development of a lab-on-a-chip (LOC) for the manipulation and experimental testing of individual pollen tubes. The design was specifically tailored to...
Chapter
The plant cell wall is a complex material made of polysaccharides, proteins, ions and water. As an external envelope around the cell it resists the internal turgor pressure. During plant cell growth, the cell wall material must yield to allow the cell to expand in a controlled spatial and temporal pattern. Modeling this behavior has been approached...
Article
Full-text available
A lab-on-a-chip device with a knot shaped microfluidic network is presented to enable trapping of single pollen grains at the entrances of a series of microchannels. This set-up serves to create identical growth conditions for serially arranged tip growing plant cells such as pollen tubes. The design consists of an inlet to introduce the pollen sus...
Article
Full-text available
A biocompatible polydimethylsiloxane (PDMS) biomicrofluidic platform is designed, fabricated and tested to study protuberance growth of single plant cells in a micro-vitro environment. The design consists of an inlet to introduce the cell suspension into the chip, three outlets to conduct the medium or cells out of the chip, a main distribution cha...
Article
Invasive behaviour is the hallmark of a variety of cell types of animal, plant, and fungal origin. Here we review the purpose and mechanism of invasive growth and migration. The focus is on the physical principles governing the process, the source of invasive force, and the cellular mechanism by which the cell penetrates the substrate. The current...
Data
Full-text available
Self-incompatibility (SI) in Papaver rhoeas triggers a ligand-mediated signal transduction cascade, resulting in the inhibition of incompatible pollen tube growth. Using a cytomechanical approach we have demonstrated that dramatic changes to the mechanical properties of incompatible pollen tubes are stimulated by SI induction. Microindentation reve...
Article
Full-text available
Cellular organelles move within the cellular volume and the effect of the resulting drag forces on the liquid causes bulk movement in the cytosol. The movement of both organelles and cytosol lead to an overall motion pattern called cytoplasmic streaming or cyclosis. This streaming enables the active and passive transport of molecules and organelles...
Article
Tip-growing cells have the unique property of invading living tissues and abiotic growth matrices. To do so, they exert significant penetrative forces. In plant and fungal cells, these forces are generated by the hydrostatic turgor pressure. Using the TipChip, a microfluidic lab-on-a-chip device developed for tip-growing cells, we tested the abilit...