Ethylene/polar monomer coordination copolymerization offers an attractive way of making functionalized polyolefins. However, ethylene copolymerization with industrially relevant short chain length ...alkenoic acid remain a big challenge. Here we report the efficient direct copolymerization of ethylene with vinyl acetic acid by tetranuclear nickel complexes. The protic monomer can be extended to acrylic acid, allylacetic acid, ω-alkenoic acid, allyl alcohol, and homoallyl alcohol. Based on X-ray analysis of precatalysts, control experiments, solvent-assisted electrospray ionization-mass spectrometry detection of key catalytic intermediates, and density functional theory studies, we propose a possible mechanistic scenario that involves a distinctive vinyl acetic acid enchainment enabled by Ni···Ni synergistic effects. Inspired by the mechanistic insights, binuclear nickel catalysts are designed and proved much more efficient for the copolymerization of ethylene with vinyl acetic acid or acrylic acid, achieving the highest turnover frequencies so far for both ethylene and polar monomers simultaneously.
High acetylation of angiosperm wood hinders its conversion to sugars by glycoside hydrolases, subsequent ethanol fermentation and (hence) its use for biofuel production.
We studied the REDUCED WALL ...ACETYLATION (RWA) gene family of the hardwood model Populus to evaluate its potential for improving saccharification.
The family has two clades, AB and CD, containing two genes each. All four genes are expressed in developing wood but only RWA-A and -B are activated by master switches of the secondary cell wall PtNST1 and PtMYB21. Histochemical analysis of promoter::GUS lines in hybrid aspen (Populus tremula × tremuloides) showed activation of RWA-A and -B promoters in the secondary wall formation zone, while RWA-C and -D promoter activity was diffuse. Ectopic downregulation of either clade reduced wood xylan and xyloglucan acetylation. Suppressing both clades simultaneously using the wood-specific promoter reduced wood acetylation by 25% and decreased acetylation at position 2 of Xylp in the dimethyl sulfoxideextracted xylan. This did not affect plant growth but decreased xylose and increased glucose contents in the noncellulosic monosaccharide fraction, and increased glucose and xylose yields of wood enzymatic hydrolysis without pretreatment.
Both RWA clades regulate wood xylan acetylation in aspen and are promising targets to improve wood saccharification.
Thanks to the potential of aggregation‐induced emission (AIE) phenomena, improved stabilities, and the good selectivity and sensitivity of the chemical responses exhibited by the products, ...coordination‐driven self‐assembly with tetraphenylethylene (TPE) units has recently received much attention and has been widely investigated for application in chemical sensors, cell imaging agents, light‐harvesting systems, and others. Several reviews have emerged on the topics of AIE chemistry and aggregation‐induced emission luminogen (AIEgen)‐based supramolecular assembles, however, there is still a distinct lack of full overviews of emission enhancement from the viewpoint of metal‐coordination effects. Thus, this minireview offers recent advances that have been made in the design and application of TPE‐based metallacycles, metallacages, metal‐organic frameworks (MOFs) and coordination polymers (CPs).
The motions of the tetraphenylethylene (TPE) units are restricted by coordination bonds through coordination‐driven self‐assembly, thereby their non‐radiative decay is reduced to induce fluorescence emission. This minireview offers a summary of recent advances that have been made in the design and synthesis of TPE‐based metallacycles, metallacages, metal–organic frameworks (MOFs) and coordination polymers (CPs). Their potential applications as materials for chemical sensors, cell imaging agents and light‐harvesting materials, among others, are outlined.
Cell wall hemicelluloses and pectins are O‐acetylated at specific positions, but the significance of these substitutions is poorly understood. Using a transgenic approach, we investigated how ...reducing the extent of O‐acetylation in xylan affects cell wall chemistry, plant performance and the recalcitrance of lignocellulose to saccharification. The Aspergillus niger acetyl xylan esterase AnAXE1 was expressed in Arabidopsis under the control of either the constitutively expressed 35S CAMV promoter or a woody‐tissue‐specific GT43B aspen promoter, and the protein was targeted to the apoplast by its native signal peptide, resulting in elevated acetyl esterase activity in soluble and wall‐bound protein extracts and reduced xylan acetylation. No significant alterations in cell wall composition were observed in the transgenic lines, but their xylans were more easily digested by a β‐1,4‐endoxylanase, and more readily extracted by hot water, acids or alkali. Enzymatic saccharification of lignocellulose after hot water and alkali pretreatments produced up to 20% more reducing sugars in several lines. Fermentation by Trametes versicolor of tissue hydrolysates from the line with a 30% reduction in acetyl content yielded ~70% more ethanol compared with wild type. Plants expressing 35S:AnAXE1 and pGT43B:AnAXE1 developed normally and showed increased resistance to the biotrophic pathogen Hyaloperonospora arabidopsidis, probably due to constitutive activation of defence pathways. However, unintended changes in xyloglucan and pectin acetylation were only observed in 35S:AnAXE1‐expressing plants. This study demonstrates that postsynthetic xylan deacetylation in woody tissues is a promising strategy for optimizing lignocellulosic biomass for biofuel production.
R2R3-MYB is a class of transcription factor crucial in regulating secondary cell wall development during wood formation. The regulation of wood formation in gymnosperm has been understudied due to ...its large genome size. Using Single-Molecule Real-Time sequencing, we obtained full-length transcriptomic libraries from the developmental stem of Cunninghamia lanceolata, a perennial conifer known as Chinese fir. The R2R3-MYB of C. lanceolata (hereafter named as ClMYB) associated with secondary wall development were identified based on phylogenetic analysis, expression studies and functional study on transgenic line.
The evolutionary relationship of 52 ClMYBs with those from Arabidopsis thaliana, Eucalyptus grandis, Populus trichocarpa, Oryza sativa, two gymnosperm species, Pinus taeda, and Picea glauca were established by neighbour-joining phylogenetic analysis. A large number of ClMYBs resided in the woody-expanded subgroups that predominated with the members from woody dicots. In contrast, the woody-preferential subgroup strictly carrying the members of woody dicots contained only one candidate. The results suggest that the woody-expanded subgroup emerges before the gymnosperm/angiosperm split, while most of the woody-preferential subgroups are likely lineage-specific to woody dicots. Nine candidates shared the same subgroups with the A. thaliana orthologs, with known function in regulating secondary wall development. Gene expression analysis inferred that ClMYB1/2/3/4/5/26/27/49/51 might participate in secondary wall development, among which ClMYB1/2/5/26/27/49 were significantly upregulated in the highly lignified compression wood region, reinforcing their regulatory role associated with secondary wall development. ClMYB1 was experimentally proven a transcriptional activator that localised in the nucleus. The overexpression of ClMYB1 in Nicotiana benthamiana resulted in an increased lignin deposition in the stems. The members of subgroup S4, ClMYB3/4/5 shared the ERF-associated amphiphilic repression motif with AtMYB4, which is known to repress the metabolism of phenylpropanoid derived compounds. They also carried a core motif specific to gymnosperm lineage, suggesting divergence of the regulatory process compared to the angiosperms.
This work will enrich the collection of full-length gymnosperm-specific R2R3-MYBs related to stem development and contribute to understanding their evolutionary relationship with angiosperm species.
In natural systems, plant-symbiont-pathogen interactions play important roles in mitigating abiotic and biotic stresses in plants. Symbionts have their own special recognition ways, but they may ...share some similar characteristics with pathogens based on studies of model microbes and plants. Multi-omics technologies could be applied to study plant-microbe interactions, especially plant-endophyte interactions. Endophytes are naturally occurring microbes that inhabit plants, but do not cause apparent symptoms in them, and arise as an advantageous source of novel metabolites, agriculturally important promoters, and stress resisters in their host plants. Although biochemical, physiological, and molecular investigations have demonstrated that endophytes confer benefits to their hosts, especially in terms of promoting plant growth, increasing metabolic capabilities, and enhancing stress resistance, plant-endophyte interactions consist of complex mechanisms between the two symbionts. Further knowledge of these mechanisms may be gained by adopting a multi-omics approach. The involved interaction, which can range from colonization to protection against adverse conditions, has been investigated by transcriptomics and metabolomics. This review aims to provide effective means and ways of applying multi-omics studies to solve the current problems in the characterization of plant-microbe interactions, involving recognition and colonization. The obtained results should be useful for identifying the key determinants in such interactions and would also provide a timely theoretical and material basis for the study of interaction mechanisms and their applications.
To develop proton‐conducting materials under low‐humidity conditions and at moderate working temperature still remains challenging for fuel‐cell technology. Here, a new type of proton‐conducting ...material, EIMS‐HTFSA@MIL, which was prepared by impregnating the binary ionic liquid, EIMS‐HTFSA (EIMS=1‐(1‐ethyl‐3‐imidazolium)propane‐3‐sulfonate; HTFSA=N,N‐bis(trifluoromethanesulfonyl)amide), into a mesoporous metal–organic framework, MIL‐101 (Cr3F(H2O)2O(BDC)3⋅n H2O (n≈0.25, BDC=1,4‐benzenedicarboxylate)) is reported. By taking advantage of the ionic‐liquid properties, such as high thermal stability, non‐volatility, non‐flammability, and low corrosivity, EIMS‐HTFSA@MIL shows potential application as a safe electrolyte in proton conduction above 100 °C.
Ionic liquid makes it conduct: A binary ionic liquid was rationally designed and facilely impregnated into a MOF support to construct an anhydrous proton conductor with high conductivity above 100 °C, which opens a new way up to achieve novel anhydrous PEMs materials with high performance and low safety hazards at moderate temperature.
Tomato cultivars with contrasting resistance to pathogens regulate root exudates differentially in response to Ralstonia solanacearum attacks. However, strategies using innate root exudates against ...infection remain unknown. This study analyzed the innate root exudates of two tomato cultivars and their functions in regulating R. solanacearum infection. The innate root exudates differed between the two cultivars. Astaxanthin released from resistant plants inhibited colonization by R. solanacearum but promoted motility, while neferine released from susceptible plants suppressed motility and colonization. The secretion of astaxanthin in resistant tomatoes promoted the growth of biocontrol fungi in soil and reduced the abundance of pathogenic fungi. Neferine secreted by the susceptible cultivar inhibited the relative abundance of the bacterial-biocontrol-related Bacillus genus, indirectly reducing the soil’s immune capacity. This study revealed contrasting strategies using root exudates in resistant and susceptible tomato cultivars to cope with R. solanacearum infection, providing a basis for breeding disease-resistant cultivars.
The efficacy of immunotherapy in advanced HER2‐mutated non‐small‐cell lung cancer (NSCLC) remains incomprehensively studied. A total of 107 NSCLC patients with de novo HER2 mutations were ...retrospectively studied at Guangdong Lung Cancer Institute GLCI cohort, exon 20 insertions (ex20ins): 71.0% to compare clinical/molecular features and immune checkpoint inhibitor (ICI)‐based therapy efficacy between patients with ex20ins and non‐ex20ins. Two external cohorts (TCGA, n = 21; META‐ICI, n = 30) were used for validation. In the GLCI cohort, 68.2% of patients displayed programmed death‐ligand 1 (PD‐L1) expression < 1%. Compared with ex20ins patients, non‐ex20ins patients had more concurrent mutations in the GLCI cohort (P < 0.01) and a higher tumour mutation burden in the TCGA cohort (P = 0.03). Under ICI‐based therapy, advanced NSCLC patients with non‐ex20ins had potentially superior progression‐free survival median: 13.0 vs. 3.6 months, adjusted hazard ratio (HR): 0.31, 95% confidence interval (CI): 0.11–0.83 and overall survival (median: 27.5 vs. 8.1 months, adjusted HR: 0.39, 95% CI: 0.13–1.18) to ex20ins patients, consistent with findings in the META‐ICI cohort. ICI‐based therapy may serve as an option for advanced HER2‐mutated NSCLC, with potentially better efficacy in non‐ex20ins patients. Further investigations are warranted in clinical practice.
HER2‐mutated non‐small‐cell lung cancer (NSCLC) patients with HER2 mutations other than exon 20 insertions (non‐ex20ins) had higher tumour mutation burden than patients with HER2 ex20ins, whereas similar programmed death‐ligand 1 expression was observed. Under immune checkpoint inhibitor‐based therapy, advanced NSCLC patients with HER2 non‐ex20ins had potentially superior progression‐free survival and overall survival compared with patients with HER2 ex20ins.
Dendrobium catenatum is a classical and precious dual-use plant for both medicine and food in China. It was first recorded in Shen Nong’s Herbal Classic, and has the traditional functions of ...nourishing yin, antipyresis, tonifying the stomach, and promoting fluid production. The stem is its medicinal part and is rich in active polysaccharide glucomannan. As an excellent dietary fiber, glucomannan has been experimentally confirmed to be involved in anti-cancer, enhancing immunity, lowering blood sugar and blood lipids, etc. Here, the status quo of the D. catenatum industry, the structure, bioactivities, biosynthesis pathway and key genes of glucomannan are systematically described to provide a crucial foundation and theoretical basis for understanding the value of D. catenatum and the potential application of glucomannan in crop biofortification.
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