Helical growth in plant organs: mechanisms and significance

Turing patterns on rotating spiral growing domains

We investigate the emergence of Turing patterns in a system growing as a rotating spiral in two dimensions, utilizing the photosensitivity of the chlorine dioxide-iodine-malonic acid (CDIMA) reaction to control the growth process. We observe the formation of single and multiple (double and triple) stationary spiral patterns as well as transitional patterns. From numerical simulations of the Lengyel-Epstein model with an additional term to account for the effects of illumination on the reaction, we analyze the relationship between the final morphologies and the radial and angular growth velocities, identify conditions conducive to the formation of transitional structures, examine the importance of the size of the initial nucleation site in determining the spiral's multiplicity, and evaluate the stability and robustness of these Turing patterns. Our results indicate how inclusion of rotational degrees of freedom in the growth process may lead to the formation of a diverse new class of patterns in chemical and biological systems.

Liana attachment to supports leads to profound changes in xylem anatomy and transcriptional profile of cambium and differentiating xylem

Wood serves crucial functions in plants, yet our understanding of the mechanisms governing the composition, arrangement, and dimensions of its cells remains limited. The abrupt transition from nonlianescent to lianescent xylem in lianas represents an excellent model to address the underlying mechanisms, although consistent triggering factors for this process remain uncertain. In this study we examined how physical support attachment impacts the development of lianescent xylem in Bignonia magnifica (Bignoniaceae), employing a comprehensive approach integrating detailed anatomical analysis with gene expression profiling of cambium and differentiating xylem. Our findings demonstrate that attachment to physical supports triggers the formation of lianescent xylem, leading to increased vessel size, broader vessel distribution, reduced fibre content, and higher potential specific water conductivity than nonlianescent xylem. These shifts in wood anatomy coincide with the downregulation of genes associated with cell division and cell wall biosynthesis, and the upregulation of transcription factors, defense/cell death, and hormone-responsive genes in the lianescent xylem. Our findings provide insights into the regulation of xylem differentiation, driven by response to environmental stimuli. Additionally, they shed light on the mechanisms underlying the adaptation of lianas to climbing.

Handedness in Animals and Plants

Structural and functional asymmetries are traceable in every form of life, and some lateralities are homologous. Functionally speaking, the division of labour between the two halves of the brain is a basic characteristic of the nervous system that arose even before the appearance of vertebrates. The most well-known expression of this specialisation in humans is hand dominance, also known as handedness. Even if hand/limb/paw dominance is far more commonly associated with the presence of a nervous system, it is also observed in its own form in aneural organisms, such as plants. To date, little is known regarding the possible functional significance of this dominance in plants, and many questions remain open (among them, whether it reflects a generalised behavioural asymmetry). Here, we propose a comparative approach to the study of handedness, including plants, by taking advantage of the experimental models and paradigms already used to study laterality in humans and various animal species. By taking this approach, we aim to enrich our knowledge of the concept of handedness across natural kingdoms.

KINASE-INDUCIBLE DOMAIN INTERACTING 8 regulates helical pod morphology in Medicago truncatula

Leguminosae exhibits a wide diversity of legume forms with varying degrees of spiral morphologies, serving as an ideal clade for studying the growth and development of spiral organs. While soybean (Glycine max) develops straight pods, the pod of the model legume Medicago truncatula is a helix structure. Despite the fascinating structures and intensive description of the pods in legumes, little is known regarding the genetic mechanism underlying the highly varied spirality of the legume pods. In this study, we found that KINASE-INDUCIBLE DOMAIN INTERACTING 8 (MtKIX8) plays a key role in regulating the pod structure and spirality in M. truncatula. Unlike the coiled and barrel-shaped helix pods of the wild type, the pods of the mtkix8 mutant are loose and deformed and lose the topologic structure as observed in the wild-type pods. In the pods of the mtkix8 mutant, the cells proliferate more actively and overly expand, particularly in the ventral suture, resulting in uncoordinated growth along the dorsal and ventral sutures of pods. The core cell cycle genes CYCLIN D3s are upregulated in the mtkix8 pods, leading to the prolonged growth of the ventral suture region of the pods. Our study revealed the key role of MtKIX8 in regulating seed pod development in M. truncatula and demonstrates a genetic regulatory model underlying the establishment of the helical pod in legumes.

Development of a 45K pepper GBTS liquid-phase gene chip and its application in genome-wide association studies

Introduction

Pepper (Capsicum spp.) is a vegetable that is cultivated globally and has undergone extensive domestication, leading to a significant diversification in its agronomic traits. With the advancement of genomics in pepper and the reduction in sequencing costs, the high-throughput detection of single nucleotide polymorphisms (SNPs) and small insertions-deletions (indels) has become increasingly critical for analyzing pepper germplasms and improving breeding programs. As a result, there is a pressing need for a cost-effective, high-throughput, and versatile technique suitable for both foreground and background selection in pepper breeding.

Methods

In the present study, Python-based web scraping scripts were utilized to systematically extract data from published literatures and relevant sequence databases focusing on pepper genomes. Subsequent to data extraction, SNPs and indels were meticulously identified and filtered. This process culminated in the delineation of core polymorphic sites, which were instrumental in the development of specific probes. Following this, comprehensive phenotypic and genotypic analyses were conducted on a diverse collection of 420 pepper germplasms. Concurrently, a genome-wide association study (GWAS) was conducted to elucidate the genetic determinants of helical fruit shape in peppers.

Results

In this study, a 45K pepper Genotyping-By-Target-Sequencing (GBTS) liquid-phase gene chip was developed on the GenoBaits platform. This chip is composed of 45,389 probes, of which 42,535 are derived from core polymorphic sites (CPS) in the background genetic landscape, while 2,854 are associated with foreground agronomic traits, spanning across 43 traits. The CPS probes are spaced at an average interval of 68 Kb. We have assessed the performance of this chip on 420 pepper germplasms, with successful capture of target DNA fragments by 45,387 probes. Furthermore, the probe capture ratio surpassed 70% in 410 of the 420 germplasms tested. Using this chip, we have efficiently genotyped 273 germplasms for spiciness levels and elucidated the genetic relationships among 410 pepper germplasms. Our results allowed for precise clustering of sister lines and C. chinense germplasms. In addition, through a GWAS for helical fruit shape, we identified three quantitative trait loci (QTLs): heli2.1, heli11.1, and heli11.2. Within the heli11.1 QTL, a gene encoding the tubulin alpha chain was identified, suggesting its potential role in the helical growth pattern of pepper fruits.

Discussion

In summary, the 45K pepper GBTS liquid-phase gene chip offers robust detection of polymorphic sites and is a promising tool for advancing research into pepper germplasm and the breeding of new pepper varieties.

The mechanism underlying asymmetric bending of lateral petals in Delphinium (Ranunculaceae)

During the process of flower opening, most petals move downward in the direction of the pedicel (i.e., epinastic movement). In most Delphinium flowers, however, their two lateral petals display a very peculiar movement, the mirrored helical rotation, which requires the twist of the petal stalk. However, in some lineages, their lateral petals also exhibit asymmetric bending that increases the degree of mirrored helical rotation, facilitating the formation of a 3D final shape. Notably, petal asymmetric bending is a novel trait that has not been noticed yet, so its morphological nature, developmental process, and molecular mechanisms remain largely unknown. Here, by using D. anthriscifolium as a model, we determined that petal asymmetric bending was caused by the localized expansion of cell width, accompanied by the specialized array of cell wall nano-structure, on the adaxial epidermis. Digital gene analyses, gene expression, and functional studies revealed that a class I homeodomain-leucine zipper family transcription factor gene, DeanLATE MERISTEM IDENTITY1 (DeanLMI1), contributes to petal asymmetric bending; knockdown of it led to the formation of explanate 2D petals. Specifically, DeanLMI1 promotes cell expansion in width and influences the arrangement of cell wall nano-structure on the localized adaxial epidermis. These results not only provide a comprehensive portrait of petal asymmetric bending for the first time but also shed some new insights into the mechanisms of flower opening and helical movement in plants.

Cellulose assembles into helical bundles of uniform handedness in cell walls with abnormal pectin composition

Plant cells and organs grow into a remarkable diversity of shapes, as directed by cell walls composed primarily of polysaccharides such as cellulose and multiple structurally distinct pectins. The properties of the cell wall that allow for precise control of morphogenesis are distinct from those of the individual polysaccharide components. For example, cellulose, the primary determinant of cell morphology, is a chiral macromolecule that can self-assemble in vitro into larger-scale structures of consistent chirality, and yet most plant cells do not display consistent chirality in their growth. One interesting exception is the Arabidopsis thaliana rhm1 mutant, which has decreased levels of the pectin rhamnogalacturonan-I and causes conical petal epidermal cells to grow with a left-handed helical twist. Here, we show that in rhm1 the cellulose is bundled into large macrofibrils, unlike the evenly distributed microfibrils of the wild type. This cellulose bundling becomes increasingly severe over time, consistent with cellulose being synthesized normally and then self-associating into macrofibrils. We also show that in the wild type, cellulose is oriented transversely, whereas in rhm1 mutants, the cellulose forms right-handed helices that can account for the helical morphology of the petal cells. Our results indicate that when the composition of pectin is altered, cellulose can form cellular-scale chiral structures in vivo, analogous to the helicoids formed in vitro by cellulose nano-crystals. We propose that an important emergent property of the interplay between rhamnogalacturonan-I and cellulose is to permit the assembly of nonbundled cellulose structures, providing plants flexibility to orient cellulose and direct morphogenesis.

The regulation of the cell wall by glycosylphosphatidylinositol-anchored proteins in Arabidopsis

A polysaccharides-based cell wall covers the plant cell, shaping it and protecting it from the harsh environment. Cellulose microfibrils constitute the cell wall backbone and are embedded in a matrix of pectic and hemicellulosic polysaccharides and glycoproteins. Various environmental and developmental cues can regulate the plant cell wall, and diverse glycosylphosphatidylinositol (GPI)-anchored proteins participate in these regulations. GPI is a common lipid modification on eukaryotic proteins, which covalently tethers the proteins to the membrane lipid bilayer. Catalyzed by a series of enzymic complexes, protein precursors are post-translationally modified at their hydrophobic carboxyl-terminus in the endomembrane system and anchored to the lipid bilayer through an oligosaccharidic GPI modification. Ultimately, mature proteins reach the plasma membrane via the secretory pathway facing toward the apoplast and cell wall in plants. In Arabidopsis, more than three hundred GPI-anchored proteins (GPI-APs) have been predicted, and many are reported to be involved in diverse regulations of the cell wall. In this review, we summarize GPI-APs involved in cell wall regulation. GPI-APs are proposed to act as structural components of the cell wall, organize cellulose microfibrils at the cell surface, and during cell wall integrity signaling transduction. Besides regulating protein trafficking, the GPI modification is potentially governed by a GPI shedding system that cleaves and releases the GPI-anchored proteins from the plasma membrane into the cell wall.

Hierarchical self-assembly into chiral nanostructures

One basic principle regulating self-assembly is associated with the asymmetry of constituent building blocks or packing models. Using asymmetry to manipulate molecular-level devices and hierarchical functional materials is a promising topic in materials sciences and supramolecular chemistry. Here, exemplified by recent major achievements in chiral hierarchical self-assembly, we show how chirality may be utilized in the design, construction and evolution of highly ordered and complex chiral nanostructures. We focus on how unique functions can be developed by the exploitation of chiral nanostructures instead of single basic units. Our perspective on the future prospects of chiral nanostructures via the hierarchical self-assembly strategy is also discussed.

Modeling the cholesteric pitch of apolar cellulose nanocrystal suspensions using a chiral hard-bundle model

Cellulose nanocrystals (CNCs) are naturally sourced elongated nanocolloids that form cholesteric phases in water and apolar solvents. It is well accepted that CNCs are made of bundles of crystalline microfibrils clustered side-by-side, and there is growing evidence that each individual microfibril is twisted. Yet, the origin of the chiral interactions between CNCs remains unclear. In this work, CNCs are described with a simple model of chiral hard splinters, enabling the prediction of the pitch using density functional theory and Monte Carlo simulations. The predicted pitch P compares well with experimental observations in cotton-based CNC dispersions in apolar solvents using surfactants but also with qualitative trends caused by fractionation or tip sonication in aqueous suspensions. These results suggest that the bundle shape induces an entropy-driven chiral interaction between CNCs, which is the missing link in explaining how chirality is transferred from the molecular scale of cellulose chains to the cholesteric order.

Stalling interkinetic nuclear migration in curved pseudostratified epithelium of developing cochlea

The bending of epithelial tubes is a fundamental process in organ morphogenesis, driven by various multicellular behaviours. The cochlea in the mammalian inner ear is a representative example of spiral tissue architecture where the continuous bending of the duct is a fundamental component of its morphogenetic process. Although the cochlear duct morphogenesis has been studied by genetic approaches extensively, it is still unclear how the cochlear duct morphology is physically formed. Here, we report that nuclear behaviour changes are associated with the curvature of the pseudostratified epithelium during murine cochlear development. Two-photon live-cell imaging reveals that the nuclei shuttle between the luminal and basal edges of the cell is in phase with cell-cycle progression, known as interkinetic nuclear migration, in the flat region of the pseudostratified epithelium. However, the nuclei become stationary on the luminal side following mitosis in the curved region. Mathematical modelling together with perturbation experiments shows that this nuclear stalling facilitates luminal-basal differential growth within the epithelium, suggesting that the nuclear stalling would contribute to the bending of the pseudostratified epithelium during the cochlear duct development. The findings suggest a possible scenario of differential growth which sculpts the tissue shape, driven by collective nuclear dynamics.

The YTHDF proteins ECT2 and ECT3 bind largely overlapping target sets and influence target mRNA abundance, not alternative polyadenylation

Gene regulation via N6-methyladenosine (m⁶A) in mRNA involves RNA-binding proteins that recognize m⁶A via a YT521-B homology (YTH) domain. The plant YTH domain proteins ECT2 and ECT3 act genetically redundantly in stimulating cell proliferation during organogenesis, but several fundamental questions regarding their mode of action remain unclear. Here, we use HyperTRIBE (targets of RNA-binding proteins identified by editing) to show that most ECT2 and ECT3 targets overlap, with only a few examples of preferential targeting by either of the two proteins. HyperTRIBE in different mutant backgrounds also provides direct views of redundant, ectopic, and specific target interactions of the two proteins. We also show that contrary to conclusions of previous reports, ECT2 does not accumulate in the nucleus. Accordingly, inactivation of ECT2, ECT3, and their surrogate ECT4 does not change patterns of polyadenylation site choice in ECT2/3 target mRNAs, but does lead to lower steady-state accumulation of target mRNAs. In addition, mRNA and microRNA expression profiles show indications of stress response activation in ect2/ect3/ect4 mutants, likely via indirect effects. Thus, previous suggestions of control of alternative polyadenylation by ECT2 are not supported by evidence, and ECT2 and ECT3 act largely redundantly to regulate target mRNA, including its abundance, in the cytoplasm.

GhUBX controlling helical growth results in production of stronger cotton fiber

Cotton fiber is an excellent model for studying plant cell elongation and cell wall biogenesis as well because they are highly polarized and use conserved polarized diffuse growth mechanism. Fiber strength is an important trait among cotton fiber qualities due to ongoing changes in spinning technology. However, the molecular mechanism of fiber strength forming is obscure. Through map-based cloning, we identified the fiber strength gene GhUBX. Increasing its expression, the fiber strength of the transgenic cotton was significantly enhanced compared to the receptor W0 and the helices number of the transgenic fiber was remarkably increased. Additionally, we proved that GhUBX regulates the fiber helical growth by degrading the GhSPL1 via the ubiquitin 26S–proteasome pathway. Taken together, we revealed the internal relationship between fiber helices and fiber stronger. It will be useful for improving the fiber quality in cotton breeding and illustrating the molecular mechanism for plant twisted growth.

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Isolation of the first fiber strength gene GhUBX using map-based cloning strategy

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Verification of the function of GhUBX experimentally in transgenic cotton

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Link helices to the cotton fiber strength, that more helices make fiber stronger

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An ubiquitin–proteasome system regulating the development of cotton fiber

Three-dimensional quantification of twisting in the Arabidopsis petiole

Organisms have a variety of three-dimensional (3D) structures that change over time. These changes include twisting, which is 3D deformation that cannot happen in two dimensions. Twisting is linked to important adaptive functions of organs, such as adjusting the orientation of leaves and flowers in plants to align with environmental stimuli (e.g. light, gravity). Despite its importance, the underlying mechanism for twisting remains to be determined, partly because there is no rigorous method for quantifying the twisting of plant organs. Conventional studies have relied on approximate measurements of the twisting angle in 2D, with arbitrary choices of observation angle. Here, we present the first rigorous quantification of the 3D twisting angles of Arabidopsis petioles based on light sheet microscopy. Mathematical separation of bending and twisting with strict definition of petiole cross-sections were implemented; differences in the spatial distribution of bending and twisting were detected via the quantification of angles along the petiole. Based on the measured values, we discuss that minute degrees of differential growth can result in pronounced twisting in petioles.

Phototunable self-oscillating system driven by a self-winding fiber actuator

Self-oscillating systems that enable autonomous, continuous motions driven by an unchanging, constant stimulus would have significant applications in intelligent machines, advanced robotics, and biomedical devices. Despite efforts to gain self-oscillations have been made through artificial systems using responsive soft materials of gels or liquid crystal polymers, these systems are plagued with problems that restrict their practical applicability: few available oscillation modes due to limited degrees of freedom, inability to control the evolution between different modes, and failure under loading. Here we create a phototunable self-oscillating system that possesses a broad range of oscillation modes, controllable evolution between diverse modes, and loading capability. This self-oscillating system is driven by a photoactive self-winding fiber actuator designed and prepared through a twistless strategy inspired by the helix formation of plant-tendrils, which endows the system with high degrees of freedom. It enables not only controllable generation of three basic self-oscillations but also production of diverse complex oscillatory motions. Moreover, it can work continuously over 1270000 cycles without obvious fatigue, exhibiting high robustness. We envision that this system with controllable self-oscillations, loading capability, and mechanical robustness will be useful in autonomous, self-sustained machines and devices with the core feature of photo-mechanical transduction.

Self-oscillating systems that enable autonomous motions driven by a constant stimulus find applications in numerous fields but these systems are plagued with problems that restrict their practical applicability. Here, the authors create a photoactive self-winding fiber actuator that possesses a broad range of oscillation modes, controllable evolution between diverse modes, and loading capability.

Bio-Inspired Soft Grippers Based on Impactive Gripping

Grasping and manipulation are fundamental ways for many creatures to interact with their environments. Different morphologies and grasping methods of "grippers" are highly evolved to adapt to harsh survival conditions. For example, human hands and bird feet are composed of rigid frames and soft joints. Compared with human hands, some plants like Drosera do not have rigid frames, so they can bend at arbitrary points of the body to capture their prey. Furthermore, many muscular hydrostat animals and plant tendrils can implement more complex twisting motions in 3D space. Recently, inspired by the flexible grasping methods present in nature, increasingly more bio-inspired soft grippers have been fabricated with compliant and soft materials. Based on this, the present review focuses on the recent research progress of bio-inspired soft grippers based on impactive gripping. According to their types of movement and a classification model inspired by biological "grippers", soft grippers are classified into three types, namely, non-continuum bending-type grippers, continuum bending-type grippers, and continuum twisting-type grippers. An exhaustive and updated analysis of each type of gripper is provided. Moreover, this review offers an overview of the different stiffness-controllable strategies developed in recent years.

Retrograde ERK activation waves drive base-to-apex multicellular flow in murine cochlear duct morphogenesis

A notable example of spiral architecture in organs is the mammalian cochlear duct, where the morphology is critical for hearing function. Genetic studies have revealed necessary signaling molecules, but it remains unclear how cellular dynamics generate elongating, bending, and coiling of the cochlear duct. Here, we show that extracellular signal-regulated kinase (ERK) activation waves control collective cell migration during the murine cochlear duct development using deep tissue live-cell imaging, Förster resonance energy transfer (FRET)-based quantitation, and mathematical modeling. Long-term FRET imaging reveals that helical ERK activation propagates from the apex duct tip concomitant with the reverse multicellular flow on the lateral side of the developing cochlear duct, resulting in advection-based duct elongation. Moreover, model simulations, together with experiments, explain that the oscillatory wave trains of ERK activity and the cell flow are generated by mechanochemical feedback. Our findings propose a regulatory mechanism to coordinate the multicellular behaviors underlying the duct elongation during development.

Mechanistic Insights into Plant Chiral Growth

The latent left–right asymmetry (chirality) of vascular plants is best witnessed as a helical elongation of cylindrical organs in climbing plants. Interestingly, helical handedness is usually fixed in given species, suggesting genetic control of chirality. Arabidopsis thaliana, a small mustard plant, normally does not twist but can be mutated to exhibit helical growth in elongating organs. Genetic, molecular and cell biological analyses of these twisting mutants are providing mechanistic insights into the left–right handedness as well as how potential organ skewing is suppressed in most plants. Growth direction of elongating plant cells is determined by alignment of cellulose microfibrils in cell walls, which is guided by cortical microtubules localized just beneath the plasma membrane. Mutations in tubulins and regulators of microtubule assembly or organization give rise to helical arrangements of cortical microtubule arrays in Arabidopsis cells and cause helical growth of fixed handedness in axial organs such as roots and stems. Whether tubulins are assembled into a microtubule composed of straight or tilted protofilaments might determine straight or twisting growth. Mechanistic understanding of helical plant growth will provide a paradigm for connecting protein filament structure to cellular organization.

Self-Winding Gelatin-Amyloid Wires for Soft Actuators and Sensors

The origin of self-winding mechanisms in plants' tendrils has fascinated scientists for centuries and continues to inspire developments in material science and nanotechnology. Here, bioinspired water-responsive wires that replicate these mechanisms, including the formation of coils and chiral perversions, are presented. A right-handed gelatin matrix is loaded with rigid left-handed amyloid fibrils and roll-dry-spun into wires in which self-winding activation emerges from simultaneous bending and twisting deformations. Wire bending is a consequence of amyloid fibrils' concentration and distribution within the wire, whereas twisting is controlled by amyloid fibrils' orientation. The resultant wires can be functionalized by organic molecules and inorganic nanoparticles, and potential applications in magnetic actuators and sensors are demonstrated. The simple fabrication method and the remarkable spontaneous self-winding response of these gelatin-amyloid wires exemplify how biomaterials based on mixed proteins have striking potential to develop advanced and tunable properties that can serve robotics, soft machines, and engineering systems.

Metallo-Helicoid with Double Rims: Polymerization Followed by Folding by Intramolecular Coordination

In this study, we established a feasible strategy to construct a new type of metallo-polymer with helicoidal structure through the combination of covalent polymerization and intramolecular coordination-driven self-assembly. In the design, a tetratopic monomer (M) was prepared with two terminal alkynes in the outer rim for polymerization, and two terpyridines (TPYs) in the inner rim for subsequent folding by selective intramolecular coordination. Then, the linear covalent polymer (P) was synthesized by polymerization of M via Glaser-Hay homocoupling reaction. Finally, intramolecular coordination interactions between TPYs and Zn(II) folded the backbone of P into a right- or left-handed metallo-helicoid (H) with double rims. Owing to multiple positive charges on the inner rim of helicoid, double-stranded DNA molecules (dsDNA) could interact with H through electrostatic interactions. Remarkably, dsDNA allowed exclusive formation of H with right handedness by means of chiral induction.

The loss of function of HEL, which encodes a cellulose synthase interactive protein, causes helical and vine-like growth of tomato

Helical growth is an economical way for plant to obtain resources. The classic microtubule-microfibril alignment model of Arabidopsis helical growth involves restriction of the appropriate orientation of cellulose microfibrils appropriately in the cell walls. However, the molecular mechanism underlying tomato helical growth remains unknown. Here, we identified a spontaneous tomato helical (hel) mutant with right-handed helical cotyledons and petals but left-handed helical stems and true leaves. Genetic analysis revealed that the hel phenotype was controlled by a single recessive gene. Using map-based cloning, we cloned the HEL gene, which encodes a cellulose interacting protein homologous to CSI1 of Arabidopsis. We identified a 27 bp fragment replacement that generated a premature stop codon. Transgenic experiments showed that the helical growth phenotype could be restored by the allele of this gene from wild-type Pyriforme. In contrast, the knockout mutation of HEL in Pyriforme via CRISPR/Cas9 resulted in helical growth. These findings shed light on the molecular control of the helical growth of tomato.

Recurrent requirement for the m6A-ECT2/ECT3/ECT4 axis in the control of cell proliferation during plant organogenesis

mRNA methylation at the N6-position of adenosine (m6A) enables multiple layers of post-transcriptional gene control, often via RNA-binding proteins that use a YT521-B homology (YTH) domain for specific m6A recognition. In Arabidopsis, normal leaf morphogenesis and rate of leaf formation require m6A and the YTH-domain proteins ECT2, ECT3 and ECT4. In this study, we show that ect2/ect3 and ect2/ect3/ect4 mutants also exhibit slow root and stem growth, slow flower formation, defective directionality of root growth, and aberrant flower and fruit morphology. In all cases, the m6A-binding site of ECT proteins is required for in vivo function. We also demonstrate that both m6A methyltransferase mutants and ect2/ect3/ect4 exhibit aberrant floral phyllotaxis. Consistent with the delayed organogenesis phenotypes, we observe particularly high expression of ECT2, ECT3 and ECT4 in rapidly dividing cells of organ primordia. Accordingly, ect2/ect3/ect4 mutants exhibit decreased rates of cell division in leaf and vascular primordia. Thus, the m6A-ECT2/ECT3/ECT4 axis is employed as a recurrent module to stimulate plant organogenesis, at least in part by enabling rapid cellular proliferation.

Wet-spinning of magneto-responsive helical chitosan microfibers

Helical structures can be found in nature at various length scales ranging from the molecular level to the macroscale. Due to their ability to store mechanical energy and to optimize the accessible surface area, helical shapes contribute particularly to motion-driven processes and structural reinforcement. Due to these special features, helical fibers have become highly attractive for biotechnological and tissue engineering applications. However, there are only a few methods available for the production of biocompatible helical microfibers. Given that, we present here a simple technique for the fabrication of helical chitosan microfibers with embedded magnetic nanoparticles. Composite fibers were prepared by wet-spinning and coagulation in an ethanol bath. Thereby, no toxic components were introduced into the wet-spun chitosan fibers. After drying, the helical fibers had a diameter of approximately 130 µm. Scanning electron microscopy analysis of wet-spun helices revealed that the magnetic nanoparticles agglomerated into clusters inside the fiber matrix. The helical constructs exhibited a diameter of approximately 500 µm with one to two windings per millimeter. Due to their ferromagnetic properties they are easily attracted to a permanent magnet. The results from the tensile testing show that the helical chitosan microfibers exhibited an average Young's modulus of 14 MPa. By taking advantage of the magnetic properties of the feedstock solution, the production of the helical fibers could be automated. The fabrication of the helical fibers was achieved by utilizing the magnetic properties of the feedstock solution and winding the emerging fiber around a rotating magnetic collector needle upon coagulation. In summary, our helical chitosan microfibers are very attractive for future use in magnetic tissue engineering or for the development of biocompatible actuator systems.

Herbicidal Activity of Thymbra capitata (L.) Cav. Essential Oil

The bioherbicidal potential of Thymbra capitata (L.) Cav. essential oil (EO) and its main compound carvacrol was investigated. In in vitro assays, the EO blocked the germination and seedling growth of Erigeron canadensis L., Sonchus oleraceus (L.) L., and Chenopodium album L. at 0.125 µL/mL, of Setaria verticillata (L.) P.Beauv., Avena fatua L., and Solanum nigrum L. at 0.5 µL/mL, of Amaranthus retroflexus L. at 1 µL/mL and of Portulaca oleracea L., and Echinochloa crus-galli (L.) P.Beauv. at 2 µL/mL. Under greenhouse conditions, T. capitata EO was tested towards the emergent weeds from a soil seedbank in pre and post emergence, showing strong herbicidal potential in both assays at 4 µL/mL. In addition, T. capitata EO, applied by spraying, was tested against P. oleracea, A. fatua and E. crus-galli. The species showed different sensibility to the EO, being E. crus-galli the most resistant. Experiments were performed against A. fatua testing T. capitata EO and carvacrol applied by spraying or by irrigation. It was verified that the EO was more active at the same doses in monocotyledons applied by irrigation and in dicotyledons applied by spraying. Carvacrol effects on Arabidopsis root morphology were also studied.

A new viewpoint on antlers reveals the evolutionary history of deer (Cervidae, Mammalia)

Recent molecular phylogeny of deer revealed that the characters of antlers previously focused on are homoplasious, and antlers tend to be considered problematic for classification. However, we think antlers are important tools and reconsidered and analysed the characters and structures to use them for classification. This study developed a method to describe the branching structure of antlers by using antler grooves, which are formed on the antlers by growth, and then projecting the position of the branching directions of tines on the burr circumference. By making diagrams, comparing the branching structure interspecifically, homologous elements (tines, beams, and processes) of the antlers of 25 species of 16 genera were determined. Subsequently, ancestral state reconstruction was performed on the fixed molecular phylogenetic tree. It was revealed that Capreolinae and Cervini gained respective three-pointed antlers independently, and their subclades gained synapomorphous tines. We found new homologous and synapomorphous characters, as the antler of Eld’s deer, which has been classified in Rucervus, is structurally close to that of Elaphurus rather than that of Rucervus, consistent with molecular phylogeny. The methods of this study will contribute to the understanding of the branching structure and phylogeny of fossil species and uncover the evolutionary history of Cervidae.

Genetic localization of the SPC gene controlling pod coiling direction in Medicago truncatula

BACKGROUND

Handedness in plants introduced by helical growth of organs is frequently observed, and it has fascinated plant scientists for decades. However, the genetic control of natural handedness has not been revealed. In the model legume Medicago truncatula, pods can be coiled in a clockwise or anti-clockwise manner, providing a model for genetic analysis of plant handedness.

OBJECTIVE

We aimed to localize the Sense of Pod Coiling (SPC) gene controlling pod coiling direction in M. truncatula.

METHODS

Linkage analysis was used with a biparental population for fine mapping of the SPC gene. The genome sequence of M. truncatula Mt4.0 was used for marker identification and physical mapping. Single nucleotide polymorphisms (SNPs) between the parental lines were converted to CAPS (cleaved amplified polymorphic sequences) markers. Genetic map was constructed using the software JoinMap version 3.0. Gene predication and annotation provided by the M. truncatula genome database (http://www.medicagogenome.org) was confirmed with the programs of FGENESH and Pfam 32.0, respectively. Quantitative reverse transcription PCR (qRT-PCR) was used to analyze the relative expression levels of candidate genes.

RESULTS

The genetic analysis indicated that the anti-clockwise coiling is dominant to clockwise and is controlled by the single gene, SPC. The SPC gene was delimited to a 250 kb-region on Chromosome 7. Total of 15 protein-coding genes were identified in the SPC locus through gene annotation and sequence analysis. Of those, two genes, potentially encoding a receptor-like kinase and a vacuolar cation/proton exchanger respectively, were selected as candidates for the SPC gene.

CONCLUSIONS

The result presented here lay a foundation for gene cloning of SPC, which will help us to understand the molecular mechanisms underlying helical growth in plant organs.

Taking inspiration from climbing plants: methodologies and benchmarks-a review

One of the major challenges in robotics and engineering is to develop efficient technological solutions that are able to cope with complex environments and unpredictable constraints. Taking inspiration from natural organisms is a well-known approach to tackling these issues. Climbing plants are an important, yet innovative, source of inspiration due to their ability to adapt to diverse habitats, and can be used as a model for developing robots and smart devices for exploration and monitoring, as well as for search and rescue operations. This review reports the main methodologies and approaches used by scientists to investigate and extract the features of climbing plants that are relevant to the artificial world in terms of adaptation, movement, and behaviour, and it summarizes the current available climbing plant-inspired engineering solutions.

Circumnutation and Growth of Inflorescence Stems of Arabidopsis thaliana in Response to Microgravity under Different Photoperiod Conditions

Circumnutation is a periodic growth movement, which is an important physiological mechanism of plants to adapt to their growth environments. Gravity and photoperiod are two key environmental factors in regulating the circumnutation of plants, but the coordination mechanism between them is still unknown. In this study, the circumnutation of Arabidopsis thaliana inflorescence stems was investigated on board the Chinese recoverable satellite SJ-10 and the Chinese spacelab TG-2. Plants were cultivated in a special plant culture chamber under two photoperiod conditions [a long-day (LD) light: dark cycle of 16:8 h, and a short-day (SD) light: dark cycle of 8:16 h]. The plant growth and movements were followed by two charge-coupled device (CCD) cameras. The parameter revealed a daily (24 h) modulation on both TG-2 and SJ-10, under both the LD and the SD conditions. The inhibition of circumnutation was more apparent by microgravity under the SD in comparison with that under the LD condition, suggesting the synergistic effects of the combined microgravity and photoperiod on the circumnutation in space. In addition, an infradian rhythm (ca. 21 days long) on the TG-2 was also observed.

Handedness in plant cell expansion: a mutant perspective on helical growth

Many plant mutants are known that exhibit some degree of helical growth. This 'twisted' phenotype has arisen frequently in mutant screens of model organisms, but it is also found in cultivars of ornamental plants, including trees. The phenomenon, in many cases, is based on defects in cell expansion symmetry. Any complete model which explains the anisotropy of plant cell growth must ultimately explain how helical cell expansion comes into existence - and how it is normally avoided. While the mutations observed in model plants mainly point to the microtubule system, additional affected components involve cell wall functions, auxin transport and more. Evaluation of published data suggests a two-way mechanism underlying the helical growth phenomenon: there is, apparently, a microtubular component that determines handedness, but there is also an influence arising in the cell wall that feeds back into the cytoplasm and affects cellular handedness. This idea is supported by recent reports demonstrating the involvement of the cell wall integrity pathway. In addition, there is mounting evidence that calcium is an important relayer of signals relating to the symmetry of cell expansion. These concepts suggest experimental approaches to untangle the phenomenon of helical cell expansion in plant mutants.

Bioinspired Superelastic Electroconductive Fiber for Wearable Electronics

Electroconductive fibers (E-fibers) with excellent flexibility and elasticity are crucial for the advancement of smart textiles for wearable electronics. However, the current metal-based conductive wires are not capable of satisfying the practical demands attributing to their limited stretchability and inferior antiabrasion ability. Herein, we report a superelastic and electroconductive fiber with a spring-like structure, inspired by the unique coiled tendril structures of climbing plants. The E-fiber is constructed by wrapping a flexible yet conductive carbon nanotube/polydimethylsiloxane (CNT/PDMS) composite yarn onto a polyester filament. In this system, the polyester filament provides mechanical robustness and stretchability, while the coiled CNT/PDMS composite yarn (C/P CY) offers sufficient conductivity. Notably, the as-fabricated E-fiber possesses high stretchability (165%), exceptional tensile force (660 cN), extraordinary antiabrasion ability, and remarkable electrical stability under various deformations. In addition, the great air permeability and electrothermal stability are also achieved, which are essential for comfortable wear and steady conduction. The developed E-fiber based on CNT composite wrapping yarn, together with its exceptional mechanical and electrical performance, provides the material with promising prospects for practical applications in wearable electronics.

Homoclinic and Heteroclinic Orbits in Climbing Cucumber Tendrils

Many biomaterials utilize chiral growth to imitate biological functions. A prominent example can be found in growing cucumbers, which use tendrils as winding support for both fixation and climbing. A number of tendril-mimicking materials and artificial plant-like mechanical machines have been developed to imitate tendril deformation. However, tendrils tend to not only show spiral or parallel shapes, but also a combination of both configurations. It remains unclear whether these morphologies are regular and how they form mechanically. Here, the morphology of climbing tendrils as a complex nonlinear phenomenon is investigated via experimental and theoretical approaches. The results of the experiments clarify the relationship between tendril morphologies and actual tendril growth as well as relevant stress characteristics during the climbing of a support by the tendril, and their mechanical properties. On this basis, the three-dimensional configuration problem of a cylinder-constrained rod has been utilized to describe the phenomenon of a tendril climbing support. The phenomena of spiral and parallel configuration combinations in tendrils could be effectively explained by studying similar homoclinic and heteroclinic orbits. Applying these results accurately guides the development of mimicking material.

Mechanical Conflicts in Twisting Growth Revealed by Cell-Cell Adhesion Defects

Many plants grow organs and tissues with twisted shapes. Arabidopsis mutants with impaired microtubule dynamics exhibit such a phenotype constitutively. Although the activity of the corresponding microtubule regulators is better understood at the molecular level, how large-scale twisting can emerge in the mutants remains largely unknown. Classically, oblique cortical microtubules would constrain the deposition of cellulose microfibrils in cells, and such conflicts at the cell level would be relaxed at the tissue scale by supracellular torsion. This model implicitly assumes that cell-cell adhesion is a key step to transpose local mechanical conflicts into a macroscopic twisting phenotype. Here we tested this prediction using the quasimodo1 mutant, which displays cell-cell adhesion defects. Using the spriral2/tortifolia1 mutant with hypocotyl helical growth, we found that qua1-induced cell-cell adhesion defects restore straight growth in qua1-1 spr2-2. Detached cells in qua1-1 spr2-2 displayed helical growth, confirming that straight growth results from the lack of mechanical coupling between cells rather than a restoration of SPR2 activity in the qua1 mutant. Because adhesion defects in qua1 depend on tension in the outer wall, we also showed that hypocotyl twisting in qua1-1 spr2-2 could be restored when decreasing the matrix potential of the growth medium, i.e., by reducing the magnitude of the pulling force between adjacent cells, in the double mutant. Interestingly, the induction of straight growth in qua1-1 spr2-2 could be achieved beyond hypocotyls, as leaves also displayed a flat phenotype in the double mutant. Altogether, these results provide formal experimental support for a scenario in which twisted growth in spr2 mutant would result from the relaxation of local mechanical conflicts between adjacent cells via global organ torsion.

Calcium signals are necessary to establish auxin transporter polarity in a plant stem cell niche

In plants mechanical signals pattern morphogenesis through the polar transport of the hormone auxin and through regulation of interphase microtubule (MT) orientation. To date, the mechanisms by which such signals induce changes in cell polarity remain unknown. Through a combination of time-lapse imaging, and chemical and mechanical perturbations, we show that mechanical stimulation of the SAM causes transient changes in cytoplasmic calcium ion concentration (Ca²⁺) and that transient Ca²⁺ response is required for downstream changes in PIN-FORMED 1 (PIN1) polarity. We also find that dynamic changes in Ca²⁺ occur during development of the SAM and this Ca²⁺ response is required for changes in PIN1 polarity, though not sufficient. In contrast, we find that Ca²⁺ is not necessary for the response of MTs to mechanical perturbations revealing that Ca²⁺ specifically acts downstream of mechanics to regulate PIN1 polarity response.

Auxin transport and microtubule orientation respond to mechanical stimulation at the shoot apical meristem. Here Li et al. show that mechanical stimulation causes cytosolic calcium concentration transients, and preventing such changes impairs reorientation of the PIN1 auxin efflux carrier, but not of microtubules.

Differential growth and shape formation in plant organs

Morphogenesis is a phenomenon by which a wide variety of functional organs are formed in biological systems. In plants, morphogenesis is primarily driven by differential growth of tissues. Much effort has been devoted to identifying the role of genetic and biomolecular pathways in regulating cell division and cell expansion and in influencing shape formation in plant organs. However, general principles dictating how differential growth controls the formation of complex 3D shapes in plant leaves and flower petals remain largely unknown. Through quantitative measurements on live plant organs and detailed finite-element simulations, we show how the morphology of a growing leaf is determined by both the maximum value and the spatial distribution of growth strain. With this understanding, we develop a broad scientific framework for a morphological phase diagram that is capable of rationalizing four configurations commonly found in plant organs: twisting, helical twisting, saddle bending, and edge waving. We demonstrate the robustness of these findings and analyses by recourse to synthetic reproduction of all four configurations using controlled polymerization of a hydrogel. Our study points to potential approaches to innovative geometrical design and actuation in such applications as building architecture, soft robotics and flexible electronics.

ANGUSTIFOLIA contributes to the regulation of three-dimensional morphogenesis in the liverwort Marchantia polymorpha

Arabidopsis thaliana mutants deficient in ANGUSTIFOLIA (AN) exhibit several phenotypes at the sporophyte stage, such as narrow and thicker leaves, trichomes with two branches, and twisted fruits. It is thought that these phenotypes are caused by abnormal arrangement of cortical microtubules (MTs). AN homologs are present in the genomes of diverse land plants, including the basal land plant Marchantia polymorpha, and their molecular functions have been shown to be evolutionarily conserved in terms of the ability to complement the A. thaliana an-1 mutation. However, the roles of ANs in bryophytes, the life cycle of which includes a dominant haploid gametophyte generation, remain unknown. Here, we have examined the roles of AN homologs in the model bryophyte M. polymorpha (MpAN). Mpan knockout mutants showed abnormal twisted thalli and suppressed thallus growth along the growth axis. Under weak blue light conditions, elongated thallus growth was observed in wild-type plants, whereas it was suppressed in the mutants. Moreover, disordered cortical MT orientations were observed. Our findings suggest that MpAN contributes to three-dimensional morphogenesis by regulating cortical MT arrangement in the gametophytes of bryophytes.

Arabidopsis petiole torsions induced by lateral light or externally supplied auxin require microtubule-associated TORTIFOLIA1/SPIRAL2

Although rather inconspicuous, movements are an important adaptive trait of plants. Consequently, light- or gravity-induced movements leading to organ bending have been studied intensively. In the field, however, plant movements often result in organ twisting rather than bending. This study investigates the mechanism of light- or gravity-induced twisting movements, coined "helical tropisms." Because certain Arabidopsis cell expansion mutants show organ twisting under standard growth conditions, we here investigated how the right-handed helical growth mutant tortifolia1/spiral2 (tor1) responds when stimulated to perform helical tropisms. When leaves were illuminated from the left, tor1 was capable of producing left-handed petiole torsions, but these occurred at a reduced rate. When light was applied from right, tor1 plants rotated their petioles much faster than the wild-type. Applying auxin to the lateral-distal side of wild-type petioles produced petiole torsions in which the auxinated flank was consistently turned upwards. This kind of movement was not observed in tor1 mutants when auxinated to produce left-handed movements. Investigating auxin transport in twisting petioles based on the DR5-marker suggested that auxin flow was apical-basal rather than helical. While cortical microtubules of excised wild-type petioles oriented transversely when stimulated with auxin, those of tor1 were largely incapable of reorientation. Together, our results show that tor1 is a tropism mutant and suggest a mechanism in which auxin and microtubules both contribute to helical tropisms.

Omeprazole Enhances Mechanical Stress-Induced Root Growth Reduction in Arabidopsis thaliana

Mechanical sensing is one of the most fundamental processes for sessile plants to survive and grow. The response is known to involve calcium elevation in the cell. Arabidopsis seedlings grown horizontally on agar plates covered with a dialysis membrane show a 2-fold reduction in root growth compared with those grown vertically, a response to mechanical stress generated due to gravitropism of the root. To understand the molecular mechanism of how plant roots sense and respond to mechanical stimuli, we screened chemical libraries for compounds that affect the horizontal root growth in this experimental system and found that, while having no effect on root gravitropism, omeprazole known as a proton pump inhibitor significantly enhanced the mechanical stress-induced root growth reduction especially in lower pH media. In contrast, omeprazole reversed neither the alleviation of the mechanical stress-induced growth reduction caused by calcium depletion nor the insensitivity to the mechanical stress in the ethylene signaling mutant ein2. Together with the finding that omeprazole increased expression of touch-induced genes and ETHYLENE RESPONSE FACTOR1, our results suggest that the target of omeprazole mediates ethylene signaling in the root growth response to mechanical stress.

The molecular control of tendril development in angiosperms

The climbing habit has evolved multiple times during the evolutionary history of angiosperms. Plants evolved various strategies for climbing, such as twining stems, tendrils and hooks. Tendrils are threadlike organs with the ability to twine around other structures through helical growth; they may be derived from a variety of structures, such as branches, leaflets and inflorescences. The genetic capacity to grow as a tendrilled climber existed in some of the earliest land plants; however, the underlying molecular basis of tendril development has been studied in only a few taxa. Here, we summarize what is known about the molecular basis of tendril development in model and candidate model species from key tendrilled families, that is, Fabaceae, Vitaceae, Cucurbitaceae, Passifloraceae and Bignoniaceae. Studies on tendril molecular genetics and development show the molecular basis of tendril formation and ontogenesis is diverse, even when tendrils have the same ontogenetic origin, for example leaflet-derived tendrils in Fabaceae and Bignoniaceae. Interestingly, all tendrils perform helical growth during contact-induced coiling, indicating that such ability is not correlated with their ontogenetic origin or phylogenetic history. Whether the same genetic networks are involved during helical growth in diverse tendrils still remains to be investigated.

Cellulose-Based Biomimetics and Their Applications

Nature has been producing cellulose since long before man walked the surface of the earth. Millions of years of natural design and testing have resulted in cellulose-based structures that are an inspiration for the production of synthetic materials based on cellulose with properties that can mimic natural designs, functions, and properties. Here, five sections describe cellulose-based materials with characteristics that are inspired by gratings that exist on the petals of the plants, structurally colored materials, helical filaments produced by plants, water-responsive materials in plants, and environmental stimuli-responsive tissues found in insects and plants. The synthetic cellulose-based materials described herein are in the form of fibers and films. Fascinating multifunctional materials are prepared from cellulose-based liquid crystals and from composite cellulosic materials that combine functionality with structural performance. Future and recent applications are outlined.

A Biomimetic Conductive Tendril for Ultrastretchable and Integratable Electronics, Muscles, and Sensors

Adaptive tendril coiling of climbing plants has long inspired the artificial soft microsystem for actuation and morphing. The current bionic research efforts on tendril coiling focus on either the preparation of materials with the coiling geometry or the design of self-shaping materials. However, the realization of two key functional features of the tendril, the spring-like buffering connection and the axial contraction, remains elusive. Herein, we devise a conductive tendril by fusing conductive yarns into tendril configuration, bypassing the prevailing conductivity constraints and mechanical limitations. The conductive tendril not only inherits an electrophysiology buffering mechanics with exceptional conductance retention ability against extreme stretching but also exhibits excellent contractive actuation performance. The integrative design of the ultraelastic conductive tendril shows a combination of compliant mobility, actuation, and sensory capabilities. Such smart biomimetic material holds great prospects in the fields of ultrastretchable electronics, artificial muscles, and wearable bioelectronic therapeutics.

Soft Tendril-Inspired Grippers: Shape Morphing of Programmable Polymer-Paper Bilayer Composites

Nastic movements in plants that occur in response to environmental stimuli have inspired many man-made shape-morphing systems. Tendril is an exemplification serving as a parasitic grasping component for the climbing plants by transforming from a straight shape into a coiled configuration via the asymmetric contraction of internal stratiform plant tissues. Inspired by tendrils, this study using a three-dimensional (3D) printing approach developed a class of soft grippers with preprogrammed deformations being capable of imitating the general motions of plant tendrils, including bending, spiral, and helical distortions for grasping. These grippers initially in flat configurations were tailored from a polymer-paper bilayer composite sheet fabricated via 3D printing a polymer on the paper substrate with different patterns. The rough and porous paper surface provides a printed polymer that is well-adhered to the paper substrate which in turn serves as a passive strain-limiting layer. During printing, the melted polymer filament is stretched, enabling the internal strain to be stored in the printed polymer as memory, and then it can be thermally released, which will be concurrently resisted by the paper layer, resulting in various transformations based on the different printed geometries. These obtained transformations were then used for designing grippers to grasp objects with corresponding motions. Furthermore, a fully equipped robotic tendril with three segments was reproduced, where one segment was used for grasping the object and the other two segments were used for forming a tendril-like twistless spring-like structure. This study further helps in the development of soft robots using active polymer materials for engineered systems.

Circumnutation and distribution of phytohormones in Vigna angularis epicotyls

Circumnutation is a plant growth movement in which the tips of axial organs draw a circular orbit. Although it has been studied since the nineteenth century, its mechanism and significance are still unclear. Greened adzuki bean (Vigna angularis) epicotyls exhibited a clockwise circumnutation in the top view with a constant period of 60 min under continuous white light. The bending zone of circumnutation on the epicotyls was always located in the region 1-3 cm below the tip, and its basal end was almost identical to the apical end of the region where the epicotyl had completely elongated. Therefore, epidermal cells that construct the bending zone are constantly turning over with their elongation growth. Since exogenously applied auxin transport inhibitors and indole-3-acetic acid (IAA) impaired circumnutation without any effect on the elongation rate of epicotyls, we attempted to identify the distribution pattern of endogenous auxin. Taking advantage of its large size, we separated the bending zone of epicotyls into two halves along the longitudinal axis, either convex/concave pairs in the plane of curvature of circumnutation or pre-convex/pre-concave pairs perpendicular to the plane. By liquid chromatography-mass spectrometry, we found, for the first time, that IAA and gibberellin A₁ were asymmetrically distributed in the pre-convex part in the region 1-2 cm below the tip. This region of epicotyl sections exhibited the highest responsiveness to exogenously applied hormones, and the latent period between the hormone application and the detection of a significant enhancement in elongation was 15 min. Our results suggest that circumnutation in adzuki bean epicotyls with a 60 min period is maintained by differential growth in the bending zone, which reflects the hormonal status 15 min before and which is shifting sequentially in a circumferential direction. Cortical microtubules do not seem to be involved in this regulation.

The simplest supramolecular helix

Diethylamine is the smallest and simplest molecule that features a supramolecular helix as its lowest energy aggregate.

Convergent Evolution and the Diverse Ontogenetic Origins of Tendrils in Angiosperms

Climbers are abundant in tropical forests, where they constitute a major functional plant type. The acquisition of the climbing habit in angiosperms constitutes a key innovation. Successful speciation in climbers is correlated with the development of specialized climbing strategies such as tendrils, i.e., filiform organs with the ability to twine around other structures through helical growth. Tendrils are derived from a variety of morphological structures, e.g., stems, leaves, and inflorescences, and are found in various plant families. In fact, tendrils are distributed throughout the angiosperm phylogeny, from magnoliids to asterids II, making these structures a great model to study convergent evolution. In this study, we performed a thorough survey of tendrils within angiosperms, focusing on their origin and development. We identified 17 tendril types and analyzed their distribution through the angiosperm phylogeny. Some interesting patterns emerged. For instance, tendrils derived from reproductive structures are exclusively found in the Core Eudicots, except from one monocot species. Fabales and Asterales are the orders with the highest numbers of tendrilling strategies. Tendrils derived from modified leaflets are particularly common among asterids, occurring in Polemoniaceae, Bignoniaceae, and Asteraceae. Although angiosperms have a large number of tendrilled representatives, little is known about their origin and development. This work points out research gaps that should help guide future research on the biology of tendrilled species. Additional research on climbers is particularly important given their increasing abundance resulting from environmental disturbance in the tropics.

New highly hydrated cellulose microfibrils with a tendril helical morphology extracted from agro-waste material: application to removal of dyes from waste water

Cocoa bean shells are a by-product of the cocoa bean processing industry. Highly hydrated cellulose microfibrils with special morphology were obtained from this by-product and used as adsorbent material for waste water treatment.