CSLD5-mediated cell wall remodelling regulates tissue mechanics and shoot meristem growth.

New tissues and organs in plants develop from stem cells located in meristematic tissues. Cell wall-mediated mechanics has been proposed to play crucial roles in controlling stem cell activity. Here, we show that in Arabidopsis shoot apical meristems (SAMs) Cellulose Synthase Like-D5 (CSLD5)-mediated cell wall synthesis modulates tissue mechanics.

Differential growth is an emergent property of mechanochemical feedback mechanisms in curved plant organs.

Differential growth is central to eukaryotic morphogenesis. We showed using cellular imaging, simulations, and perturbations that light-induced differential growth in a curved organ, the Arabidopsis thaliana apical hook, emerges from the longitudinal expansion of subepidermal cells, acting in parallel with a differential in the material properties of epidermal cell walls that resist expansion. The greater expansion of inner hook cells that results in apical hook opening is gated by wall alkalinity and auxin, both of which are depleted upon illumination.

Altering the substitution and cross-linking of glucuronoarabinoxylans affects cell wall architecture in Brachypodium distachyon.

The Poaceae family of plants provides cereal crops that are critical for human and animal nutrition, and also, they are an important source of biomass. Interacting plant cell wall components give rise to recalcitrance to digestion; thus, understanding the wall molecular architecture is important to improve biomass properties. Xylan is the main hemicellulose in grass cell walls.

Structural differences of cell walls in earlywood and latewood of and their contribution to biomass recalcitrance.

Scots pine ( L.) is an evergreen coniferous tree with wide distribution and good growth performance in a range of habitats. Therefore, wood from is produced in many managed forests and is frequently used in industry.

Stiffness transitions in new walls post-cell division differ between gemmae and thaliana leaves.

Plant morphogenesis is governed by the mechanics of the cell wall-a stiff and thin polymeric box that encloses the cells. The cell wall is a highly dynamic composite material. New cell walls are added during cell division.

Ectopic callose deposition into woody biomass modulates the nano-architecture of macrofibrils.

Plant biomass plays an increasingly important role in the circular bioeconomy, replacing non-renewable fossil resources. Genetic engineering of this lignocellulosic biomass could benefit biorefinery transformation chains by lowering economic and technological barriers to industrial processing. However, previous efforts have mostly targeted the major constituents of woody biomass: cellulose, hemicellulose and lignin.

Observing cellulose synthases at emerging secondary thickenings in developing xylem vessels of the plant root using airyscan confocal microscopy.

Movement of cellulose synthase particles have so far been observed on the plant epidermis that are amenable to confocal imaging, yielding appreciable signal and resolution to observe small plasma membrane-localised particles. Presented here is a method, using airyscan confocal microscopy, that permits similar information to be obtained at depth within the developing protoxylem vessels of intact roots.

Eudicot primary cell wall glucomannan is related in synthesis, structure, and function to xyloglucan.

Hemicellulose polysaccharides influence assembly and properties of the plant primary cell wall (PCW), perhaps by interacting with cellulose to affect the deposition and bundling of cellulose fibrils. However, the functional differences between plant cell wall hemicelluloses such as glucomannan, xylan, and xyloglucan (XyG) remain unclear. As the most abundant hemicellulose, XyG is considered important in eudicot PCWs, but plants devoid of XyG show relatively mild phenotypes.

An Overview of Cryo-Scanning Electron Microscopy Techniques for Plant Imaging.

Many research questions require the study of plant morphology, in particular cells and tissues, as close to their native context as possible and without physical deformations from some preparatory chemical reagents or sample drying. Cryo-scanning electron microscopy (cryoSEM) involves rapid freezing and maintenance of the sample at an ultra-low temperature for detailed surface imaging by a scanning electron beam. The data are useful for exploring tissue/cell morphogenesis, plus an additional cryofracture/cryoplaning/milling step gives information on air and water spaces as well as subcellular ultrastructure.

Mechanical buckling can pattern the light-diffracting cuticle of Hibiscus trionum.

Many species have cuticular striations that play a range of roles, from pollinator attraction to surface wettability. In Hibiscus trionum, the striations span multiple cells at the base of the petal to form a pattern that produces a type of iridescence. It is postulated, using theoretical models, that the pattern of striations could result from mechanical instabilities.

The role of pectin phase separation in plant cell wall assembly and growth.

A rapidly increasing body of literature suggests that many biological processes are driven by phase separation within polymer mixtures. Liquid-liquid phase separation can lead to the formation of membrane-less organelles, which are thought to play a wide variety of roles in cell metabolism, gene regulation or signaling. One of the characteristics of these systems is that they are poised at phase transition boundaries, which makes them perfectly suited to elicit robust cellular responses to often very small changes in the cell's "environment".

Microscopy and chemical analyses reveal flavone-based woolly fibres extrude from micron-sized holes in glandular trichomes of Dionysia tapetodes.

Background: Dionysia tapetodes, a small cushion-forming mountainous evergreen in the Primulaceae, possesses a vast surface-covering of long silky fibres forming the characteristic "woolly" farina. This contrasts with some related Primula which instead form a fine powder. Farina is formed by specialized cellular factories, a type of glandular trichome, but the precise composition of the fibres and how it exits the cell is poorly understood.

Multitarget Immunohistochemistry for Confocal and Super-resolution Imaging of Plant Cell Wall Polysaccharides.

The plant cell wall (PCW) is a pecto-cellulosic extracellular matrix that envelopes the plant cell. By integrating extra-and intra-cellular cues, PCW mediates a plethora of essential physiological functions. Notably, it permits controlled and oriented tissue growth by tuning its local mechano-chemical properties.

Molecular mechanism of cytokinin-activated cell division in .

Mitogens trigger cell division in animals. In plants, cytokinins, a group of phytohormones derived from adenine, stimulate cell proliferation. Cytokinin signaling is initiated by membrane-associated histidine kinase receptors and transduced through a phosphorelay system.

A multiscale analysis of early flower development in Arabidopsis provides an integrated view of molecular regulation and growth control.

We have analyzed the link between the gene regulation and growth during the early stages of flower development in Arabidopsis. Starting from time-lapse images, we generated a 4D atlas of early flower development, including cell lineage, cellular growth rates, and the expression patterns of regulatory genes. This information was introduced in MorphoNet, a web-based platform.

Multicolor 3D-dSTORM Reveals Native-State Ultrastructure of Polysaccharides' Network during Plant Cell Wall Assembly.

The plant cell wall, a form of the extracellular matrix, is a complex and dynamic network of polymers mediating a plethora of physiological functions. How polysaccharides assemble into a coherent and heterogeneous matrix remains mostly undefined. Further progress requires improved molecular-level visualization methods that would gain a deeper understanding of the cell wall nanoarchitecture.

Pectin homogalacturonan nanofilament expansion drives morphogenesis in plant epidermal cells.

The process by which plant cells expand and gain shape has presented a challenge for researchers. Current models propose that these processes are driven by turgor pressure acting on the cell wall. Using nanoimaging, we show that the cell wall contains pectin nanofilaments that possess an intrinsic expansion capacity.

Visualization of Protein Coding, Long Noncoding, and Nuclear RNAs by Fluorescence in Situ Hybridization in Sections of Shoot Apical Meristems and Developing Flowers.

In addition to transcriptional regulation, gene expression is further modulated through mRNA spatiotemporal distribution, by RNA movement between cells, and by RNA localization within cells. Here, we have adapted RNA fluorescence in situ hybridization (FISH) to explore RNA localization in Arabidopsis (). We show that RNA FISH on sectioned material can be applied to investigate the tissue and subcellular localization of meristem and flower development genes, cell cycle transcripts, and plant long noncoding RNAs.

Structural Imaging of Native Cryo-Preserved Secondary Cell Walls Reveals the Presence of Macrofibrils and Their Formation Requires Normal Cellulose, Lignin and Xylan Biosynthesis.

The woody secondary cell walls of plants are the largest repository of renewable carbon biopolymers on the planet. These walls are made principally from cellulose and hemicelluloses and are impregnated with lignin. Despite their importance as the main load bearing structure for plant growth, as well as their industrial importance as both a material and energy source, the precise arrangement of these constituents within the cell wall is not yet fully understood.

Correlative FLIM-confocal-Raman mapping applied to plant lignin composition and autofluorescence.

Fluorescence lifetime imaging microscopy (FLIM) is a useful tool for discriminating fluorescent moieties, based on photon lifetimes, that cannot be otherwise resolved by looking solely at their excitation/emission characteristics. We present a method for correlative FLIM-confocal-Raman imaging and its application to lignin composition studies in the woody stems of the plant model Arabidopsis thaliana. Lignin is autofluorescent and exhibits characteristic fluorescence lifetimes attributed to its composition.

Cell Cycle Control by Nuclear Sequestration of CDC20 and CDH1 mRNA in Plant Stem Cells.

In eukaryotes, most RNA molecules are exported into the cytoplasm after transcription. Long noncoding RNAs (lncRNAs) reside and function primarily inside the nucleus, but nuclear localization of mRNAs has been considered rare in both animals and plants. Here we show that Arabidopsis anaphase-promoting complex/cyclosome (APC/C) coactivator genes CDC20 and CCS52B (CDH1 ortholog) are co-expressed with their target cyclin B genes (CYCBs) during mitosis.

Live Imaging of Developing Xylem In Planta.

The xylem vessel develops from a long cylindrical cell that deposits a patterned secondary wall and ending with programmed cell death. The dynamic arrangement of cell wall enzymes, membranes and the cytoskeleton can be recorded using live fluorescence imaging. The protocol presented here focuses upon the microscopy of intracellular components in developing vessels of the root using either epifluorescent or confocal microscopes.

Cell size and growth regulation in the Arabidopsis thaliana apical stem cell niche.

Cell size and growth kinetics are fundamental cellular properties with important physiological implications. Classical studies on yeast, and recently on bacteria, have identified rules for cell size regulation in single cells, but in the more complex environment of multicellular tissues, data have been lacking. In this study, to characterize cell size and growth regulation in a multicellular context, we developed a 4D imaging pipeline and applied it to track and quantify epidermal cells over 3-4 d in Arabidopsis thaliana shoot apical meristems.

S-Acylation of the cellulose synthase complex is essential for its plasma membrane localization.

Plant cellulose microfibrils are synthesized by a process that propels the cellulose synthase complex (CSC) through the plane of the plasma membrane. How interactions between membranes and the CSC are regulated is currently unknown. Here, we demonstrate that all catalytic subunits of the CSC, known as cellulose synthase A (CESA) proteins, are S-acylated.