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Musa acuminata is a main wild contributor to banana cultivars. Here, we reported a haplotype-resolved and telomere-to-telomere reference genome of M. acuminata by incorporating PacBio HiFi reads, Nanopore ultra-long reads, and Hi-C data. The genome size of the two haploid assemblies was estimated to be 469.83 Mb and 470.21 Mb, respectively. Multiple assessments confirmed the contiguity (contig N50: 16.53 Mb and 18.58 Mb; LAI: 20.18 and 19.48), completeness (BUSCOs: 98.57% and 98.57%), and correctness (QV: 45.97 and 46.12) of the genome. The repetitive sequences accounted for about half of the genome size. In total, 40,889 and 38,269 protein-coding genes were annotated in the two haploid assemblies, respectively, of which 9.56% and 3.37% were newly predicted. Genome comparison identified a large reciprocal translocation involving 3 Mb and 10 Mb from chromosomes 01 and 04 within M. acuminata. This reference genome of M. acuminata provides a valuable resource for further understanding of subgenome evolution of Musa species, and precise genetic improvement of banana. [ABSTRACT FROM AUTHOR]

Xylella fastidiosa is a bacterium that infects crops like grapevines, coffee, almonds, citrus and olives. There is little understanding of the genes that contribute to plant resistance, the genomic architecture of resistance, and the potential role of climate in shaping resistance, in part because major crops like grapevines (Vitis vinifera) are not resistant to the bacterium. Here we study a wild grapevine species, V. arizonica, that segregates for resistance. Using genome-wide association, we identify candidate resistance genes. Resistance-associated kmers are shared with a sister species of V. arizonica but not with more distant species, suggesting that resistance evolved more than once. Finally, resistance is climate dependent, because individuals from low (< 10 °C) temperature locations in the wettest quarter were typically susceptible to infection, likely reflecting a lack of pathogen pressure in colder climates. In fact, climate is as effective a predictor of resistance phenotypes as some genetic markers. We extend our climate observations to additional crops, predicting that increased pathogen pressure is more likely for grapevines and almonds than some other susceptible crops. Potential resistance genes for Xylella fastidiosa in wild grapes are identified and resistance is shown to be climate dependent. [ABSTRACT FROM AUTHOR]

Based on suitable scaffolds, constructing high-loading single-atom catalysts is a promising strategy to achieve highly efficient catalysis. Herein, using ultrathin metal-organic framework (MOF) nanosheets (2.4±0.5 nm) as the support, single-atom catalysts with high cobalt loading (6.0 wt%) were constructed (denoted as Co-MNSs) by a simple bottom-up synthetic strategy. The catalytic system of Co-MNSs exhibited an outstanding photocatalytic CO2-to-CO evolution rate of 7,041 µmol g−1 h−1 and a selectivity of 86% in aqueous media under visible-light irradiation, which has reached the top level of the reported MOF-based photocatalysts. The control experiments and theoretical calculation revealed that the Co—N4 moiety in the MOF nanosheets acted as the active site for the photocatalytic CO2-to-CO conversion. The boosted photocatalytic performance could be ascribed to the high aspect-ratio of layered Co-MNSs providing abundant accessible active sites on their surfaces, which reduced the energy barrier, improved the charge separation efficiency, and also facilitated the adsorption of CO2 to form the reactive radicals of *COOH. Our study provides an appealing strategy for constructing high-loading single-atom catalysts and demonstrates the significance of 2D ultrathin MOF nanosheets as the support in boosting CO2 photoreduction efficiency. [ABSTRACT FROM AUTHOR]

Photo-controlled living polymerization has received great attention in recent years. However, despite the great success therein, the report on photo-controlled living cationic polymerization has been greatly limited. We demonstrate here a novel decolorable, metal-free and visible light-controlled living cationic polymerization system by using tris(2,4-dimethoxyphenyl)methylium tetrafluoroborate as the photocatalyst and phosphate as the chain transfer agent (CTA) for polymerization of 4-methoxystyrene. This polymerization reaction under green LED light irradiation shows clear living characteristics including predictable molar mass, low molar-mass dispersity (Đ = 1.25), and sequential polymerization capability. In addition, the photocatalytic system exits excellent "on-off" photo switchability and shows the longest "off period" of 36 h up to now for photo-controlled cationic polymerization. Furthermore, the residual photo-catalyst is easily deactivated and decolored with addition of a base after the polymerization. The present study has extended the photo-controlled living cationic polymerization systems with new organic photocatalysts, phosphate CTA and polymerizable monomer as well as the new properties of excellent photostability and in-situ decolored capacity. Photo-controlled living polymerization has received great attention in recent years but the reports on photo-controlled living cationic polymerization are limited. Here, the authors demonstrate a metal-free and visible light-controlled living cationic polymerization using a photocatalyst and a phosphate as the chain transfer agent for the polymerization of 4-methoxystyrene. [ABSTRACT FROM AUTHOR]

Potato (Solanum tuberosum L.) is the world’s most important non-cereal food crop, and the vast majority of commercially grown cultivars are highly heterozygous tetraploids. Advances in diploid hybrid breeding based on true seeds have the potential to revolutionize future potato breeding and production1–4. So far, relatively few studies have examined the genome evolution and diversity of wild and cultivated landrace potatoes, which limits the application of their diversity in potato breeding. Here we assemble 44 high-quality diploid potato genomes from 24 wild and 20 cultivated accessions that are representative of Solanum section Petota, the tuber-bearing clade, as well as 2 genomes from the neighbouring section, Etuberosum. Extensive discordance of phylogenomic relationships suggests the complexity of potato evolution. We find that the potato genome substantially expanded its repertoire of disease-resistance genes when compared with closely related seed-propagated solanaceous crops, indicative of the effect of tuber-based propagation strategies on the evolution of the potato genome. We discover a transcription factor that determines tuber identity and interacts with the mobile tuberization inductive signal SP6A. We also identify 561,433 high-confidence structural variants and construct a map of large inversions, which provides insights for improving inbred lines and precluding potential linkage drag, as exemplified by a 5.8-Mb inversion that is associated with carotenoid content in tubers. This study will accelerate hybrid potato breeding and enrich our understanding of the evolution and biology of potato as a global staple food crop.High-quality diploid assemblies of potato genomes from 24 wild and 20 cultivated potatoes provide insights into the complex evolution and diversity of potatoes, and could have applications in the breeding of hybrid potatoes. [ABSTRACT FROM AUTHOR]

The organization of chromatin into self-interacting domains is universal among eukaryotic genomes, though how and why they form varies considerably. Here we report a chromosome-scale reference genome assembly of pepper (Capsicum annuum) and explore its 3D organization through integrating high-resolution Hi-C maps with epigenomic, transcriptomic, and genetic variation data. Chromatin folding domains in pepper are as prominent as TADs in mammals but exhibit unique characteristics. They tend to coincide with heterochromatic regions enriched with retrotransposons and are frequently embedded in loops, which may correlate with transcription factories. Their boundaries are hotspots for chromosome rearrangements but are otherwise depleted for genetic variation. While chromatin conformation broadly affects transcription variance, it does not predict differential gene expression between tissues. Our results suggest that pepper genome organization is explained by a model of heterochromatin-driven folding promoted by transcription factories and that such spatial architecture is under structural and functional constraints. The organization of chromatin into self-interacting domains is universal among eukaryotic genomes. Here, the authors report a reference-grade pepper genome assembly and use this reference to help describe the relationship among 3D chromatin conformation, chromatin function, and gene expression. [ABSTRACT FROM AUTHOR]

It remains a major challenge to identify the genes and mutations that lead to plant sexual differentiation. Here, we study the structure and evolution of the sex-determining region (SDR) in Vitis species. We report an improved, chromosome-scale Cabernet Sauvignon genome sequence and the phased assembly of nine wild and cultivated grape genomes. By resolving twenty Vitis SDR haplotypes, we compare male, female, and hermaphrodite haplotype structures and identify sex-linked regions. Coupled with gene expression data, we identify a candidate male-sterility mutation in the VviINP1 gene and potential female-sterility function associated with the transcription factor VviYABBY3. Our data suggest that dioecy has been lost during domestication through a rare recombination event between male and female haplotypes. This work significantly advances the understanding of the genetic basis of sex determination in Vitis and provides the information necessary to rapidly identify sex types in grape breeding programs. Grapevine is one of a few ancestrally dioecious crops that are reverted to hermaphroditism during domestication. Here, the authors identify candidate genes related to male- and female-sterility in grapes and describe the genetic process that led to hermaphroditism during domestication. [ABSTRACT FROM AUTHOR]

Vesicular photothermal therapy agents (PTAs) are highly desirable in photothermal therapy (PTT) for their excellent light-harvesting ability and versatile hollow compartments. However, up to now, the reported vesicular PTAs are generally self-assembled from small molecules like liposomes, and polymer vesicles have seldom been used as PTAs due to the unsatisfactory photothermal conversion efficiency resulting from the irregular packing of chromophores in the vesicle membranes. Here we report a nano-sized polymer vesicle from hyperbranched polyporphyrins with favorable photothermal stability and extraordinarily high photothermal efficiency (44.1%), showing great potential in imaging-guided PTT for tumors through in vitro and in vivo experiments. These excellent properties are attributed to the in situ supramolecular polymerization of porphyrin units inside the vesicle membrane into well-organized 1D monofilaments driven by π–π stacking. We believe the supramolecular polymerization-enhanced self-assembly process reported here will shed a new light on the design of supramolecular materials with new structures and functions. Photothermal therapy (PTT) has recently emerged as a promising approach for cancer therapy. Here, the authors report a hyperbranched polymer vesicle with favorable photothermal stability and high photothermal efficiency for PTT through a supramolecular polymerization-enhanced self-assembly strategy. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman spectroscopy (SERS) has the potential to detect pesticide residues in agricultural products. However, some systemic pesticides, such as chlorpyrifos, can enter the plant tissue, and not just stay on the surface. Consequently, many SERS studies halted at practical application because of its complexity. In this work, SERS technology was used to detect chlorpyrifos residues in tea products at the semiquantitative level. A simple pretreatment method effectively avoided interference of other fluorescent substances, and all major peaks could be distinguished on the basis of a novel substrate. A principal component analysis algorithm was applied to form a regression model, and a nanogram detection limit was obtained. Furthermore, chlorpyrifos residues in the same tea products were also measured by gas chromatography–mass spectrometry, and the results show a small range of errors. From the comparative study of the two detection methods, the results suggest the great promise of SERS technology for rapid inspection of agricultural products. [ABSTRACT FROM AUTHOR]

Alternating-structured polymers (ASPs), like alternating copolymers, regular multiblock copolymers and polycondensates, are very important polymer structures with broad applications in photoelectric materials. However, their self-assembly behaviors, especially the self-assembly of alternating copolymers, have not been clearly studied up to now. Meanwhile, the unique characteristics therein have not been systematically disclosed yet by both experiments and theories. Herein, we have performed a systematic simulation study on the self-assembly of ASPs with two coil alternating segments in solution through dissipative particle dynamics (DPD) simulations. Several morphological phase diagrams were constructed as functions of different impact parameters. Diverse self-assemblies were observed, including spherical micelles, micelle networks, worm-like micelles, disk-like micelles, multimicelle aggregates, bicontinuous micelles, vesicles, nanotubes and channelized micelles. Furthermore, a morphological evolutionary roadmap for all these self-assemblies was constructed, along with which the detailed molecular packing models and self-assembly mechanisms for each aggregate were disclosed. The ASPs were found to adopt a folded-chain mechanism in the self-assemblies. Finally, the unique characteristics for the self-assembly of alternating copolymers were revealed especially, including (1) ultra-fine and uniform feature sizes of the aggregates; (2) independence of self-assembled structures from molecular weight and molecular weight distribution; (3) ultra-small unimolecular aggregates. We believe the current work is beneficial for understanding the self-assembly of alternating structured polymers in solution and can serve as a guide for the further experiments. [ABSTRACT FROM AUTHOR]

In this work, all-atom molecular dynamics simulations were employed to study the influence of the side alkyl chain on glass transition behavior of several carbazole trimers (CT) in a temperature range from 423 to 183 K. The glass transition temperatures were obtained from the break in the slope of the volume-temperature curves and found to agree with the experimental values. The short time dynamics of four CT molecules were probed by using velocity autocorrelation functions and mean-square displacements. The current studies showed that the dynamics of CT systems can be easily interpreted through the cage effect. Furthermore, the investigation of the torsional autocorrelation function and P/P functions showed that the rotational barriers of side chains can slow down the conformational relaxation and lead to stronger temperature dependence of conformational relaxation. The relaxation time, characteristic time of P( t) and P( t) functions were all found to have Arrhenius-type temperature dependence. [ABSTRACT FROM AUTHOR]

The Pb(II) ion-imprinting electrospun crosslinked chitosan nanofiber mats were fabricated by one-step electrospinning and ion-imprinting methods and their application as adsorbents for metal ions was also investigated. The resulting chitosan nanofiber mats were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA). The Pb(II) ion-imprinting electrospun crosslinked chitosan nanofiber mats were used as adsorbents for the removal of Pb(II) ions from aqueous or acid solutions. The effects of pH values, contact time, content of crosslinker (glutaraldehyde) on Pb(II) ions adsorption were studied. The results indicated that the Pb(II) ion-imprinting electrospun crosslinked chitosan nanofiber mats had the highest adsorption capacity of 110.0 mg/g at pH 7. The kinetic study demonstrated that the adsorption of Pb(II) ions followed the pseudo-second-order model. The equilibrium isotherm data showed that the Langmuir model was the most suitable for predicting the adsorption isotherm of the studied system. The Pb(II) ion-imprinting electrospun crosslinked chitosan nanofiber mats had good adsorption selectivity, which illustrates the equilibrium adsorption capacity in the order of Pb(II)>Cu(II)>Zn(II)>Cd(II)>Ni(II). The Pb(II) ionimprinting electrospun crosslinked chitosan nanofiber mats were stable and had good reuse ability. [ABSTRACT FROM AUTHOR]

novel type of bioreducible amphiphilic multiarm hyperbranched copolymer (H40- star-PLA- SS-PEG) based on Boltorn® H40 core, poly( l-lactide) (PLA) inner-shell, and poly(ethylene glycol) (PEG) outer-shell with disulfide-linkages between the hydrophobic and hydrophilic moieties was developed as unimolecular micelles for controlled drug release triggered by reduction. The obtained H40- star-PLA- SS-PEG was characterized in detail by nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), gel permeation chromatography (GPC), differential scanning calorimeter (DSC), and thermal gravimetric analysis (TGA). Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analyses suggested that H40- star-PLA- SS-PEG formed stable unimolecular micelles in aqueous solution with an average diameter of 19 nm. Interestingly, these micelles aggregated into large particles rapidly in response to 10 mM dithiothreitol (DTT), most likely due to shedding of the hydrophilic PEG outer-shell through reductive cleavage of the disulfide bonds. As a hydrophobic anticancer model drug, doxorubicin (DOX) was encapsulated into these reductive unimolecular micelles. In vitro release studies revealed that under the reduction-stimulus, the detachment of PEG outer-shell in DOX-loaded micelles resulted in a rapid drug release. Flow cytometry and confocal laser scanning microscopy (CLSM) measurements indicated that these DOX-loaded micelles were easily internalized by living cells. Methyl tetrazolium (MTT) assay demonstrated a markedly enhanced drug efficacy of DOX-loaded H40- star-PLA- SS-PEG micelles as compared to free DOX. All of these results show that these bioreducible unimolecular micelles are promising carriers for the triggered intracellular delivery of hydrophobic anticancer drugs. [ABSTRACT FROM AUTHOR]

A novel hyperbranched multiarm copolymer of HBPO- star-PDEAEMA with a hydrophobic poly(3-ethyl-3-(hydroxymethyl) oxetane) (HBPO) core and many cationic poly(2-( N,N-diethylamino)ethyl methacrylate) (PDEAEMA) arms has been synthesized through an atom transfer radical polymerization (ATRP) method, and been applied to spontaneously reduce and stabilize gold nanoparticles (AuNPs) in water without other additional agents. The size of the nanoparticles could be effectively controlled at about 4 nm, and the nanoparticles are extremely stable in solution without aggregation even for one year. It was found that solution pH and the molar ratio of N/Au have certain effects on the size and stability of AuNPs. This work provides a simple method for the synthesis of uniform and highly stable AuNPs. [ABSTRACT FROM AUTHOR]

In this paper, we report the synthesis and self-assembly of double-hydrophilic hyperbranched graft copolymers of HPG- g-PDMAEMA, which consist of a hyperbranched polyglycerol (HPG) core and several grafted poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) arms. HPG was synthesized by cationic polymerization. Then HPG-Br macroinitiator was obtained by esterification of HPG with 2-bromoisobutyryl bromide, which was subsequently used in the preparation of HPG- g-PDMAEMA graft copolymers through atom transfer radical polymerization (ATRP) of DMAEMA monomers. The molecular structures were studied by 1H NMR and GPC. The pyrene-based fluorescent probe method, 1H NMR and DLS were used to study the self-assembly behavior of HPG- g-PDMAEMA. The drug loading and pH-responsive release properties of HPG- g-PDMAEMA were also investigated by using coumarin 102 as a model drug. The results show that the HPG- g-PDMAEMA micelles can continuously release and re-encapsulate coumarin 102 as the pH continuously changes from 11.5 to 2.5; however, this process is not totally reversible. [ABSTRACT FROM AUTHOR]

This work successfully prepared nanohybrids by in situ atom transfer radical polymerization (ATRP) of styrene from titanate nanotubes (TNTs). Fourier-transform infrared (FT-IR), pronton nuclear magnetic resonance spectroscopy (1H NMR), and thermal gravimetric analysis (TGA) were used to verify the successful graft of polystyrene (PS) chains from TNTs. Transmission electron microscopy (TEM) displayed that the obtained PS- g-TNTs nanohybrids had a core-shell structure of TNT core and PS shell. The grafted PS content was well controlled and increased with increasing of the monomer/initiator ratio. Further copolymerization of tert-butyl acrylate ( tBA) from the surface of PS- g-TNTs was studied, illustrating the “living” characteristics of the surface-induced ATRP method used in this work. [ABSTRACT FROM AUTHOR]

A small molecule core (TMP-SK3) with three terminal carboxyl groups was synthesized successfully by the reaction of 1,1,1-trihydroxymethylpropane with the excessive sebacic acid diacetic anhydride (SK). Then, the core molecule was used as a coupling agent to condensate with polyethylene glycols (PEG) of different molecular weights or polyethylene glycol monomethyl ether (PEGm) in the presence of stannous octoate as catalyst and diphenyl ether as an azeotropic agent to remove water. Thus, the three-arm star-shaped PEGs was obtained successfully and characterized by 1H-NMR, DSC, GPC and XRD etc.. DSC measurements indicate that the crystallizing and the melting temperatures of the three-arm star-shaped PEGs were different from those of the corresponding linear PEG because the existence of TMP-SK3 altered its crystallizing velocity and perfect degree of crystallization. [ABSTRACT FROM AUTHOR]

A small molecule (GMS-SA2) with one alkyl chain and two terminal carboxyl groups was synthesized successfully by the reaction of glyceryl monostearate (GMS) with excess succinic anhydride (SA). Then, GMS-SA2 was used as a coupling agent to condensate with polyethylene glycols (PEG) of different molecular weight or polyethylene glycol monomethyl ether (PEGm) in the presence of stannous octoate as catalyst and diphenyl ether as azeotropic agent. The AB2 star-shaped miktoarm copolymers were obtained successfully and were characterized by 1H-NMR, DSC, GPC, XRD, FTIR and polarizing microscopy. The results of DSC and XRD measurements indicate that the crystallization temperature and the melting temperature of the AB2 star-shaped miktoarm copolymers are different from those of the corresponding linear PEGs, because the existing of GMS-SA2 alters their crystalline growth velocity and the perfect degree of crystals. It is very important to control the crystal morphology of star-shaped copolymers by introducing the miktoarm into the starshaped polymers and adjusting its content in star-shaped polymers. [ABSTRACT FROM AUTHOR]

A series of aromatic copolyimides was successfully synthesized from the commercial pyromellitic dianhydride (PMDA) with a commercial diamine p-phenyldiamine (PDA) and a diamine 4,4′-methylenebis-(2- tert-butylaniline) (MBTBA) specially designed by the authors. The copolyimides were characterized by Infra-red (IR), Nuclear Magnetic Resonance (NMR), Gel Permeation Chromatography (GPC), Ultraviolet Visual (UV-Vis), Thermogravimetic Analysis (TGA) and Dynamic Mechanical Analysis (DMA). The copolyimide was precipitated in m-cresol in the polymerization process when the molar ratio of MBTBA and PDA was lower than 6/4. The number-average molecular weight of the soluble copolyimides measured by GPC was larger than 4.0 × 104, and the polydispersity index was higher than 1.5. Only one glass transition temperature of these copolyimides was detected around 360°C by DMA. The copolyimides did not show appreciable decomposition up to 500°C under N2, and the thermal stability of the copolyimide increased a little with the introduction of PDA into the polyimide main chain. [ABSTRACT FROM AUTHOR]