Secondary cell wall biosynthesis Zhong, Ruiqin; Cui, Dongtao; Ye, Zheng-Hua
The New phytologist,
March 2019, Volume:
221, Issue:
4
Journal Article
Peer reviewed
Open access
Secondarywalls are synthesizedin specializedcells, suchas tracheary elements andfibers, and their remarkable strength andrigidityprovide strongmechanical support tothe cells andthe plant body. The ...main components of secondary walls are cellulose, xylan, glucomannan and lignin. Biochemical, molecular and genetic studies have led to the discovery of most of the genes involved in the biosynthesis of secondary wall components. Cellulose is synthesized by cellulose synthase complexes in the plasma membrane and the recent success of in vitro synthesis of cellulose microfibrils by a single recombinant cellulose synthase isoform reconstituted into proteoliposomes opens new doors to further investigate the structure and functions of cellulose synthase complexes. Most genes involved in the glycosyl backbone synthesis, glycosyl substitutions and acetylation of xylan and glucomannan have been genetically characterized and the biochemical properties of some of their encoded enzymes have been investigated. The genes and their encoded enzymes participating in monolignol biosynthesis andmodification have been extensively studied both genetically and biochemically. A full understanding of how secondary wall components are synthesized will ultimately enable us to produce plants with custom-designed secondary wall composition tailored to diverse applications.
User participation is increasingly being seen as a way to mitigate the challenges that firms face in innovation, such as high costs and uncertainty of customer acceptance of their innovations. Thus, ...firms are establishing online platforms to support users in innovating services, such as iOS and Android platforms for mobile data service (MDS) innovation. Mobile phone platforms are characterized by technology (toolkits) and policy (rules) components that could influence user’s innovation. Additionally, attributes of user innovators (lead userness) are expected to drive their innovation behavior. Yet it is unclear how these characteristics jointly impact users’ service innovation outcomes. To address this knowledge gap, we propose a model that builds on user innovation theory and the work design literature to explain the influences of lead userness, design autonomy, toolkit support, and their interactions on user’s innovation outcomes (innovation quantity) on these platforms. We conceptualize toolkit support in terms of two constructs (i.e., ease of effort and exploration), and design autonomy in terms of three constructs (i.e., decision-making autonomy, scheduling autonomy, and work-method autonomy). The model was tested using survey and archival data from two dominant mobile phone platforms (i.e., iOS and Android). As hypothesized, lead userness, exploration through toolkits, and ease of effort through toolkits positively affect users’ innovation quantity. Additionally, decision-making autonomy and work-method autonomy influence innovation quantity, but scheduling autonomy does not. Further, the proposed three-way interactions between lead userness, toolkit support, and design autonomy constructs on users’ quantity of MDS innovation are largely supported. The findings enhance our understanding of user innovation on mobile phone platforms.
•Social exchange theory has been used to guide this study.•We identified contextual unique motivations for crowdsourcing participation.•We identified inhibitors for crowdsourcing participation.•We ...identified antecedents and consequence of trust in crowdsourcing.
Organizations are increasingly crowdsourcing their tasks to unknown individual workers, i.e., solvers. Solvers' participation is critical to the success of crowdsourcing activities. However, challenges exist in attracting solvers to participate in crowdsourcing. In this regard, prior research has mainly investigated the influences of benefit factors on solvers’ intention to participate in crowdsourcing. Thus, there is a lack of understanding of the cost factors that influence actual participation behavior, in conjunction with the benefits. Additionally, the role of trust in the cost-benefit analysis remains to be explored. Motivated thus, based on social exchange theory and context-related literature, we develop a model to explain the impacts of benefit and cost factors as well as trust on solver participation behavior in crowdsourcing. The model was tested using survey and archival data from 156 solvers on a large crowdsourcing platform. As hypothesized, monetary reward, skill enhancement, work autonomy, enjoyment, and trust were found to positively affect solvers’ participation in crowdsourcing, while cognitive effort negatively affects their participation. In addition, it was found that monetary reward positively affects trust (trust partially mediates its effect on participation behavior), while loss of knowledge power negatively affects trust. The theoretical contributions and practical implications of the study are discussed.
Iron‐substituted CoOOH porous nanosheet arrays grown on carbon fiber cloth (denoted as FexCo1−xOOH PNSAs/CFC, 0≤x≤0.33) with 3D hierarchical structures are synthesized by in situ anodic oxidation of ...α‐Co(OH)2 NSAs/CFC in solution of 0.01 m (NH4)2Fe(SO4)2. X‐ray absorption fine spectra (XAFS) demonstrate that CoO6 octahedral structure in CoOOH can be partially substituted by FeO6 octahedrons during the transformation from α‐Co(OH)2 to FexCo1−xOOH, and this is confirmed for the first time in this study. The content of Fe in FexCo1−xOOH, no more than 1/3 of Co, can be controlled by adjusting the in situ anodic oxidation time. Fe0.33Co0.67OOH PNSAs/CFC shows superior OER electrocatalytic performance, with a low overpotential of 266 mV at 10 mA cm−2, small Tafel slope of 30 mV dec−1, and high durability.
In situ anodic oxidation of α‐Co(OH)2 is developed to fabricate 3D FexCo1−xOOH porous nanosheet arrays for water oxidation. During the transformation from α‐Co(OH)2 to FexCo1−xOOH, the partial CoO6 octahedrons in CoOOH can be substituted by the unsaturated FeO6 octahedrons. The FexCo1−xOOH PNSAs/CFC exhibits the outstanding electrocatalytic performance for OER with low onset potential, small Tafel slope, and excellent durability.
Herein, we developed FeOOH/Co/FeOOH hybrid nanotube arrays (HNTAs) supported on Ni foams for oxygen evolution reaction (OER). The inner Co metal cores serve as highly conductive layers to provide ...reliable electronic transmission, and can overcome the poor electrical conductivity of FeOOH efficiently. DFT calculations demonstrate the strong electronic interactions between Co and FeOOH in the FeOOH/Co/FeOOH HNTAs, and the hybrid structure can lower the energy barriers of intermediates and thus promote the catalytic reactions. The FeOOH/Co/FeOOH HNTAs exhibit high electrocatalytic performance for OER, such as low onset potential, small Tafel slope, and excellent long‐term durability, and they are promising electrocatalysts for OER in alkaline solution.
FeOOH/Co/FeOOH hybrid nanotube arrays (HNTAs) supported on Ni foams were developed for the oxygen evolution reaction (OER). The FeOOH/Co/FeOOH HNTAs exhibit high electrocatalytic performance for OER, such as low onset potential, small Tafel slope, and excellent long‐term durability, and are promising electrocatalysts for OER in alkaline solution.
Belief-propagation (BP) decoders play a vital role in modern coding theory, but they are not suitable to decode quantum error-correcting codes because of a unique quantum feature called error ...degeneracy. Inspired by an exact mapping between BP and deep neural networks, we train neural BP decoders for quantum low-density parity-check codes with a loss function tailored to error degeneracy. Training substantially improves the performance of BP decoders for all families of codes we tested and may solve the degeneracy problem which plagues the decoding of quantum low-density parity-check codes.
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Constructing inorganic–organic hybrids with superior properties in terms of water adsorption and activation will lead to catalysts with significantly enhanced electrocatalytic activity in the ...hydrogen evolution reaction (HER) in environmentally benign neutral media. Herein, we report SiO2–polypyrrole (PPy) hybrid nanotubes supported on carbon fibers (CFs) (SiO2 /PPy NTs–CFs) as inexpensive and high‐performance electrocatalysts for the HER in neutral media. Because of the strong electronic interactions between SiO2 and PPy, the SiO2 uniquely serves as the centers for water adsorption and activation, and accordingly promotes the HER. The metal‐free SiO2 /PPy NTs–CFs displayed high catalytic activity in the HER in neutral media, such as a low onset potential and small Tafel slope, as well as excellent long‐term durability.
Working better together: SiO2/polypyrrole (PPy) hybrid nanotubes were designed as metal‐free electrocatalysts for the hydrogen evolution reaction (HER) in neutral media. The electronic interactions between SiO2 and PPy effectively enhance the adsorption and activation of water molecules, which leads to superior electrocatalytic activity and stability in the HER at neutral pH (NTs=nanotubes, CFs=carbon fibers).
Secondary walls are mainly composed of cellulose, hemicelluloses (xylan and glucomannan) and lignin, and are deposited in some specialized cells, such as tracheary elements, fibers and other ...sclerenchymatous cells. Secondary walls provide strength to these cells, which lend mechanical support and protection to the plant body and, in the case of tracheary elements, enable them to function as conduits for transporting water. Formation of secondary walls is a complex process that requires the co-ordinated expression of secondary wall biosynthetic genes, biosynthesis and targeted secretion of secondary wall components, and patterned deposition and assembly of secondary walls. Here, we provide a comprehensive review of genes involved in secondary wall biosynthesis and deposition. Most of the genes involved in the biosynthesis of secondary wall components, including cellulose, xylan, glucomannan and lignin, have been identified and their co-ordinated activation has been shown to be mediated by a transcriptional network encompassing the secondary wall NAC and MYB master switches and their downstream transcription factors. It has been demonstrated that cortical microtubules and microtubule-associated proteins play important roles in the targeted secretion of cellulose synthase complexes, the oriented deposition of cellulose microfibrils and the patterned deposition of secondary walls. Further investigation of many secondary wall-associated genes with unknown functions will provide new insights into the mechanisms controlling the formation of secondary walls that constitute the bulk of plant biomass.
FeOOH/CeO2 heterolayered nanotubes supported on Ni foam as efficient oxygen evolution electrocatalysts are reported. The hybrid structure can obviously promote the catalytic performance for the ...oxygen evolution reaction, such as low onset potential, high electroactivity, and excellent long‐term durability. This study provides a new route to the design and fabrication of electrocatalysts with high electroactivity and durability for oxygen evolution.
Summary
Secondary cell wall biosynthesis has been shown to be regulated by a suite of transcription factors. Here, we identified a new xylem vessel‐specific NAC domain transcription factor, secondary ...wall‐associated NAC domain protein5 (SND5), in Arabidopsis thaliana and studied its role in regulating secondary wall biosynthesis.
We showed that the expression of SND5 and its close homolog, SND4/ANAC075, was specifically associated with secondary wall‐containing cells and dominant repression of their functions severely reduced secondary wall thickening in these cells. Overexpression of SND4/5 as well as their homologs SND2/3 fused with the activation domain of the viral protein VP16 led to ectopic secondary wall deposition in cells that are normally parenchymatous. SND2/3/4/5 regulated the expression of the same downstream target genes as do the secondary wall NAC master switches (SWNs) by binding to and activating the secondary wall NAC binding elements (SNBEs).
Furthermore, we demonstrated that the poplar (Populus trichocarpa) orthologs of SND2/3/4/5 also activated SNBEs and regulated secondary wall biosynthesis during wood formation.
Together, these findings indicate that SND2/3/4/5 and their poplar orthologs regulate the expression of secondary wall‐associated genes through activating SNBEs and they are positioned at an upper level in the SWN‐mediated transcriptional network.
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