Fibre cables in the lacunae of Typha leaves contribute to a tensegrity structure.

BACKGROUND AND AIMS: Cables composed of long, non-lignified fibre cells enclosed in a cover of much shorter thin-walled, crystal-containing cells traverse the air chambers (lacunae) in leaves of the taller species of Typha. The non-lignified fibre cables are anchored in diaphragms composed of stellate cells of aerenchyma tissue that segment the long air chambers into smaller compartments. Although the fibre cables are easily observed and can be pulled free from the porous-to-air diaphragms, their structure and function have been ignored or misinterpreted. METHODS: Leaves of various species of Typha were dissected and fibre cables were pulled free and observed with a microscope using bright-field and polarizing optics. Maximal tensile strength of freshly removed cables was measured by hanging weights from fibre cables, and Instron analysis was used to produce curves of load versus extension until cables broke. KEY RESULTS AND CONCLUSIONS: Polarized light microscopy revealed that the cellulose microfibrils that make up the walls of the cable fibres are oriented parallel to the long axis of the fibres. This orientation ensures that the fibre cables are mechanically stiff and strong under tension. Accordingly, the measured stiffness and tensile strength of the fibre cables were in the gigapascal range. In combination with the dorsal and ventral leaf surfaces and partitions that contain lignified fibre bundles and vascular strands that are strong in compression, the very fine fibre cables that are strong under tension form a tensegrity structure. The tensegrity structure creates multiple load paths through which stresses are redistributed throughout the 1-3 m tall upright leaves of Typha angustifolia, T. latifolia, T. × glauca, T. domingensis and T. shuttleworthii. The length of the fibre cables relative to the length of the leaf blades is reduced in the last-formed leaves of flowering individuals. Fibre cables are absent in the shorter leaves of Typha minima and, if present, only extend for a few centimetres from the sheath into the leaf blade of Typha laxmannii. The advantage of the structure of the Typha leaf blade, which enables stiffness to give way to flexibility under windy conditions, is discussed for both vegetative and flowering plants.

Characterization of potential cellulose fiber from cattail fiber: A study on micro/nano structure and other properties.

Exploration of the application prospects of cattail fibers (CFs) in natural composites, and other fields is important for the sustainable development of new, green, light-weight, functional biomass materials. In this study, the physical and chemical properties, micro/nano structure, and mechanical characteristics of CFs were investigated. The CFs have a low density (618.0 kg m-3). The results of transmission electron microscopy and tensile testing data indicated that the cattail trunk fiber (CTF) bundle is composed of parenchyma cells and solid stone cells, demonstrating high specific modulus (10.1 MPa∙m3·kg-1) and high elongation at break (3.9%). In turn, the cattail branch fiber (CBF) bundle is composed of parenchyma cells with specific "half-honeycomb" shape. The inner diaphragms divide these cells into the open cavities. This structural feature endows the CTF bundles with stable structure, good oil absorption and storage capacities. The chemical component and the Fourier transform infrared spectroscopy analyses show that the CFs have higher lignin content (20.6%) and wax content (11.5%), which are conducive to the improvement of corrosion resistance, thermal stability and lipophilic-hydrophobic property of CF. Finally, the thermogravimetric analysis indicates that its final degradation temperature is 404.5 °C, which is beneficial to the increase in processability of CFs-reinforced composites.

Transcriptome -wide modulation combined with morpho-physiological analyses of Typha orientalis roots in response to lead challenge.

Lead (Pb) is a common pollutant in many environments, including in the soil, water, and/or air. Typha orientalis Presl, a large emergent aquatic plant, has been reported to function as a Pb-tolerant and Pb-accumulating plant; however, very little molecular information regarding the tolerance of T. orientalis towards Pb is known. In this study, Pb accumulation and key factors involved in the Pb stress response at different Pb concentrations were investigated. Pb was primarily accumulated in the roots and was mainly located in the cell wall and membrane systems. Differentially expressed genes (DEGs) were identified in T. orientalis roots after Pb exposure via RNA-seq analyses. In the 0.10 mM and 0.25 mM Pb2+-treated groups, a total of 3275 DEGs were detected relative to the control. Many of these genes were associated with oxidation-reduction processes, metal transport, protein kinase/phosphorylation, and DNA binding transcription factors, which were shown to be Pb-responsive DEGs. Mapping Kyoto Encyclopedia of Genes and Genomes (KEGG) database, "phenylpropanoid biosynthesis" was analyzed as the major pathway of the important modules of overlapping DEGs of 0.10 mM and 0.25 mM Pb2+ treatments. Furthermore, a lead response gene named ToLR1 with unknown function was of particular interest. The full-length of ToLR1 sequence was cloned using rapid amplification of cDNA ends (RACE) and overexpressed in Arabidopsis thaliana, which resulted in enhanced resistance to Pb stress. This is the first report providing genomic information detailing Pb responsive genes in T. orientalis. Moreover, this study provides novel insights into the molecular mechanisms underlying the response of T. orientalis and other accumulators towards Pb stress. The key genes identified in this study may serve as potential targets for genetic engineering targeting phytoremediation.

Removal and accumulation of cadmium and lead by Typha latifolia exposed to single and mixed metal solutions.

We investigated the effect of Cd and Pb on the growth of the aquatic macrophyte Typha latifolia; the removal from the solution and the accumulation of these elements by the plant were also studied. Thus, small plants of T. latifolia, collected from a noncontaminated site, were exposed for 10 days to Cd and Pb, in a single solution or in mixture solutions, at two concentrations of the metals (5 and 7.5 mg/L). Our results showed that T. latifolia removed effectively Cd and Pb from solutions and was able to accumulate these metals in the roots and, to a lesser extent, in the leaves. Our findings suggested a synergistic effect of Cd and Pb with respect to the toxicity to T. latifolia. Additionally, Cd diminished the Pb absorption by T. latifolia. Our results confirmed, using scanning electron microscopy, the internalization of Cd and Pb in T. latifolia.

Experimental study and numerical simulation on the structural and mechanical properties of Typha leaves through multimodal microscopy approaches.

The Typha leaf, with special multi-level structure, low density and excellent mechanical properties, is an ideal bionic prototype utilized for lightweight design. In order to further study the relationship between the structure and mechanical properties, the three-dimensional macroscopic morphology of Typha leaves was characterized by micro computed tomography (Micro-CT) and its internal microstructure was observed by scanning electron microscopy (SEM). The combination of experimental and computational research was carried out in this paper, to reveal and verify the effect of multi-level structure on the mechanical properties. A universal testing machine and a self-developed mechanical testing apparatus with high precision and low load were used to measure the mechanical properties of the axial compression and lateral bending of the leaves, respectively. Three models with different internal structures were established based on the above-mentioned three-dimensional morphologies. The result demonstrated that the structure of partitions and diaphragms within the Typha leaf could form a reinforcement ribs structure which could provide multiple load paths and make the process of compression and bending difficult. The further nonlinear finite element analysis through LS-DYNA proved that internal structure could improve the ability of the models to resist compression and deformation. The investigation can be the reference for lightweight thin-walled structure design and inspire the application of the bionic structural materials.

Phytoremediation of Cd, Cr, Cu, Mn, Fe, Ni, Pb and Zn from aqueous solution using Phragmites cummunis, Typha angustifolia and Cyperus esculentus.

A comparative bioaccumulation pattern and ultra structural changes were studied in Phragmites cummunis, Typha angustifolia and Cyperus esculentus in mixed metals solution of cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn). P. cummunis was observed to be a shoot accumulator for Cr, Fe, Mn, Ni, Pb, and Zn. However, T. angustifolia was found to be a root accumulator for Cd, Cr, Cu, Fe, Ni and Pb. In addition, C. esculentus also accumulated most of the tested heavy metals in the roots, while Mn and Fe were translocated up to leaves. Further, the long term metal treatment showed maximum accumulation of all heavy metals in P. cummunis followed by T. angustifolia and C. esculentus. Among heavy metals, Fe was accumulated maximum, i.e., >1000 microg g(-1) by all three plants. Simultaneously, the adverse effects on biochemical parameters were noted earlier in C. esculentus than T. angustifolia and P. cummunis. Ultra structural observation showed the cellular changes in wetland plants after longer exposure. Results revealed that P. cummunis and T. angustifolia had more potential for tested metals than C. esculentus. This study established that these wetland plants could be used for heavy metals phytoremediation from metal containing industrial wastewater.