Characterization of hemicellulose in Cunninghamia lanceolata stem during xylogenesis

In this study, hemicellulose was isolated from the apical, middle and basal segments of C. lanceolata stem to investigate the dynamic change of its structure during xylogenesis. Results showed that the C. lanceolata hemicellulose is mainly consisted of O-acetylgalactoglucomannan (GGM) which backbone is alternately linked by β-d-mannopyranosyl (Manp) and β-d-glucopyranosyl (Glcp) via (1 → 4)-glycosidic bond, while the side chains are α-d-galactopyranosyl (Galp) and acetyl. In addition, 4-O-methylglucuronoarabinoxylan (GAX) is another dominant structure of C. lanceolata hemicellulose which contains a linear backbone of (1 → 4)-β-d-xylopyranosyl (Xylp) and side chains of 4-O-Me-α-d-glucuronic acid (MeGlcpA) and α-L-arabinofuranose (Araf). The thickness of the cell wall, the ratio of GGM/GAX and the molecular weight of hemicellulose were increased as the extension of growth time. The degree of glycosyl substitutions of xylan and mannan was decreased from 10.34 % (apical) to 8.38 % (basal) and from 15.63 % (apical) to 10.49 % (basal), respectively. However, the total degree of acetylation was enhanced from 0.28 (apical) to 0.37 (basal). Transcriptome analysis showed that genes (CSLA9, IRX9H1, IRX10L, IRX15L, GMGT1, TBL19, TBL25, GUX2, GUX3, GXM1, F8H1 and F8H2) related to hemicellulose biosynthesis are mainly expressed in mature part. This study is of great significance for genetic breeding and high-value utilization of C. lanceolata.

Biominerals and waxes of Calamagrostis epigejos and Phragmites australis leaves from post-industrial habitats

Vascular plants are able to conduct biomineralization processes and collect synthesized compounds in their internal tissues or to deposit them on their epidermal surfaces. This mechanism protects the plant from fluctuations of nutrient levels caused by different levels of supply and demand for them. The biominerals reflect both the metabolic characteristics of a vascular plant species and the environmental conditions of the plant habitat. The SEM/EDX method was used to examine the surface and cross-sections of the Calamagrostis epigejos and Phragmites australis leaves from post-industrial habitats (coal and zinc spoil heaps). The results from this study have showed the presence of mineral objects on the surfaces of leaves of both grass species. The calcium oxalate crystals, amorphous calcium carbonate spheres, and different silica forms were also found in the inner tissues. The high variety of mineral forms in the individual plants of both species was shown. The waxes observed on the leaves of the studied plants might be the initializing factor for the crystalline forms and structures that are present. For the first time, wide range of crystal forms is presented for C. epigejos. The leaf samples of P. australis from the post-industrial areas showed an increased amount of mineral forms with the presence of sulfur.

Cadmium remobilization from shoot to grain is related to pH of vascular bundle in rice

The remobilization of cadmium (Cd) from shoots to grain is the key process to determine the Cd accumulation in grain. The apoplastic pH of plants is an important factor and signal in influencing on plant responding to environmental variation and inorganic elements uptake. It is proposed that pH of rice plants responds and influences on Cd remobilization from shoots to grain when rice is exposed to Cd stress. The results of hydroponic experiment showed that: pH of the rice leaf vascular bundles among 3 cultivars was almost increased, pH value of 1 cultivar was slightly increasing when rice plants were treated with Cd. The decrease degree of H⁺ concentration in leaf vascular bundles was different among cultivars. The cultivar with higher decreasing in H⁺ concentration, showed higher Cd transfer efficiency from shoots to grain. The H⁺ concentration of leaf vascular bundles under normal condition was negatively correlated to cadmium accumulation in leaf. Moreover, pH change was related to Cd accumulation in shots and remobilization from shoots to grain. Uncovering the role of pH response is a key component for the understanding Cd uptake and remobilization mechanism for rice production.

Crossing kingdoms: Using decellularized plants as perfusable tissue engineering scaffolds

Despite significant advances in the fabrication of bioengineered scaffolds for tissue engineering, delivery of nutrients in complex engineered human tissues remains a challenge. By taking advantage of the similarities in the vascular structure of plant and animal tissues, we developed decellularized plant tissue as a prevascularized scaffold for tissue engineering applications. Perfusion-based decellularization was modified for different plant species, providing different geometries of scaffolding. After decellularization, plant scaffolds remained patent and able to transport microparticles. Plant scaffolds were recellularized with human endothelial cells that colonized the inner surfaces of plant vasculature. Human mesenchymal stem cells and human pluripotent stem cell derived cardiomyocytes adhered to the outer surfaces of plant scaffolds. Cardiomyocytes demonstrated contractile function and calcium handling capabilities over the course of 21 days. These data demonstrate the potential of decellularized plants as scaffolds for tissue engineering, which could ultimately provide a cost-efficient, "green" technology for regenerating large volume vascularized tissue mass.

Chemical composition and ruminal nutrient degradability of fresh and ensiled amaranth forage

BACKGROUND

Amaranth is a crop with potential as a source of forage for ruminants that has not been well characterized. A study was conducted to determine the impact of ensiling on the nutritional quality and ruminal degradability of forage from two amaranth cultivars adapted to North America (i.e. Plainsman and D136). In particular, quantification and some microscopic characterization of oxalate found in amaranth were performed as it is an antiquality compound of concern.

RESULTS

There were limited interactions between cultivars and ensiling for most variables. Differences in chemical composition between amaranth cultivars were also limited. Ensiling reduced non-structural carbohydrate and true protein contents. The proportion of acid detergent protein was high in fresh and ensiled forages of both cultivars (average of 177 g kg(-1) crude protein). Total oxalate content averaged 30 and 25 g kg(-1) in fresh and ensiled forages respectively. Ensiling reduced soluble oxalate content. Crystals observed in amaranth were calcium oxalate druses found mostly in idioblast cells in leaf mesophyll and parenchyma of primary and secondary veins. In situ ruminal degradability data indicated that both fresh and ensiled amaranth are highly degradable in the rumen.

CONCLUSION

This study confirms that amaranth is a suitable forage for ruminant animals. Its chemical composition is comparable, for most variables, to that of other commonly used forage species.

Structure-function relationship of the foam-like pomelo peel (Citrus maxima)-an inspiration for the development of biomimetic damping materials with high energy dissipation

The mechanical properties of artificial foams are mainly determined by the choice of bulk materials and relative density. In natural foams, in contrast, variation to optimize properties is achieved by structural optimization rather than by conscious substitution of bulk materials. Pomelos (Citrus maxima) have a thick foam-like peel which is capable of dissipating considerable amounts of kinetic energy and thus this fruit represents an ideal role model for the development of biomimetic impact damping structures. This paper focuses on the analysis of the biomechanics of the pomelo peel and on its structure-function relationship. It deals with the determination of the onset strain of densification of this foam-like tissue and on how this property is influenced by the arrangement of vascular bundles. It was found here that the vascular bundles branch in a very regular manner-every 16.5% of the radial peel thickness-and that the surrounding peel tissue (pericarp) attains its exceptional thickness mainly by the expansion of existing interconnected cells causing an increasing volume of the intercellular space, rather than by cell division. These findings lead to the discussion of the pomelo peel as an inspiration for fibre-reinforced cast metallic foams with the capacity for excellent energy dissipation.

Integrated pulping and biorefining of palm residues based on semichemical cooking and fiber fractionation

This work validates a new strategy for complete utilization of palm residues by separating fibers and parenchyma for the respective purposes of pulping and biorefining. The parenchyma cells were fractionated from royal palm sheath (RPS) after neutral sulfite semichemical (NSSC) cooking for producing fermentable sugars, leaving vascular bundles for manufacturing pulp and paper. Parenchyma cells could be readily and completely screened out prior to defibration. They were more digestible by cellulase than vascular bundles or the pulp derived from them. Cellulose enzymatic digestibility (CED) of parenchyma cells rapidly reached 82% in 12-h hydrolysis and finally up to 92%. The CEDs of parenchyma were maintained around 90% at a medium solid consistency, 12% (w/w). The average length, retention and drainability of RPS pulp were all improved without loss of physical strength after removing parenchyma. This work may help establish a new platform for maximizing the utilization efficiency of parenchyma-rich biomass.

Antibodies against Yariv's reagent for immunolocalization of arabinogalactan-proteins in aerial parts of Echinacea purpurea

Arabinogalactan-proteins are glycoproteins that occur in higher plants and are involved in important processes like cell differentiation and plant growth. In the medicinal plant Echinacea purpurea L., they belong to the putative immunomodulating compounds and are structurally well characterized. For microscopic localization of arabinogalactan-proteins, synthetic (β-D-Glc)3 Yariv phenylglycoside that specifically binds to most plant arabinogalactan-proteins was used to label arabinogalactan-proteins in fresh cut sections of stems and petioles of Echinacea purpurea. Polyclonal antibodies against (β-D-Glc)3 Yariv phenylglycoside were used to detect the arabinogalactan-protein-(β-D-Glc)3 Yariv phenylglycoside complex. After addition of fluorescein isothiocyanate-conjugated secondary antibodies, the sections were analyzed by confocal laser scanning microscopy. Arabinogalactan-proteins are localized mainly in the central cylinder in the collateral vascular bundles, especially in the area of the xylem. In cell walls of fully differentiated vessels and tracheids, arabinogalactan-proteins have been detected mainly at the inner area of the wall close to the cell lumina. Intense labeling occurs around pit canals connecting adjacent vessels. Furthermore, arabinogalactan-proteins are present in the lumina of cells of the sclerenchyma caps and in companion cells of the phloem.

Anatomical and chemical alterations but not photosynthetic dynamics and apoplastic transport changes are involved in the brittleness culm mutation of rice

Brittleness culm is an important agronomic trait that has a potential usefulness in agricultural activity as animal forage although the developmental mechanism is not clear yet. In the present study, the anatomical and chemical characteristics as well as some ecophysiological features in the brittleness culm mutation of rice (Oryza sativa L.) were investigated. Compared with the wild type (WT), the brittleness culm mutant (bcm) exhibited higher culm vascular bundle distance and lower culm wall thickness, leaf interveinal distance and leaf thickness. Ratio of bundle sheath cell/whole bundle and areas of whole vascular bundles and bundle sheath of leaves were reduced while ratios of xylem and phloem to whole bundles were elevated in bcm. The Fourier transform infrared (FTIR) microspectroscopy analysis and further histochemical and physiological measurements revealed that the different contents and depositions of cell wall components such as pectins, lignin, suberin and cellulose all participated in the mutation of brittleness. However, the mutant presented no significant changes in leaf photosynthetic dynamics and apoplastic transport ability. These results strongly indicate that the alterations in anatomical and chemical characteristics, rather than changes in major ecophysiological features such as photosynthesis and apoplastic transport were involved in the brittleness mutation of rice.