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The phytohormone abscisic acid (ABA) and the Polycomb group proteins have key roles in regulating plant growth and development; however, their interplay and underlying mechanisms are not fully understood. Here, we identified an Arabidopsis (Arabidopsis thaliana) nodulin homeobox (AtNDX) protein as a negative regulator in the ABA signaling pathway. AtNDX mutants are hypersensitive to ABA, as measured by inhibition of seed germination and root growth, and the expression of AtNDX is downregulated by ABA. AtNDX interacts with the Polycomb Repressive Complex1 (PRC1) core components AtRING1A and AtRING1B in vitro and in vivo, and together, they negatively regulate the expression levels of some ABA-responsive genes. We identified ABA-INSENSITIVE (ABI4) as a direct target of AtNDX. AtNDX directly binds the downstream region of ABI4 and deleting this region increases the ABA sensitivity of primary root growth. Furthermore, ABI4 mutations rescue the ABA-hypersensitive phenotypes of ndx mutants and ABI4-overexpressing plants are hypersensitive to ABA in primary root growth. Thus, our work reveals the critical functions of AtNDX and PRC1 in some ABA-mediated processes and their regulation of ABI4.

Background The high-activity adenine base editors (ABEs), engineered with the recently-developed tRNA adenosine deaminases (TadA8e and TadA9), show robust base editing activity but raise concerns about off-target effects. Results In this study, we perform a comprehensive evaluation of ABE8e- and ABE9-induced DNA and RNA mutations in Oryza sativa. Whole-genome sequencing analysis of plants transformed with four ABEs, including SpCas9n-TadA8e, SpCas9n-TadA9, SpCas9n-NG-TadA8e, and SpCas9n-NG-TadA9, reveal that ABEs harboring TadA9 lead to a higher number of off-target A-to-G (A>G) single-nucleotide variants (SNVs), and that those harboring CRISPR/SpCas9n-NG lead to a higher total number of off-target SNVs in the rice genome. An analysis of the T-DNAs carrying the ABEs indicates that the on-target mutations could be introduced before and/or after T-DNA integration into plant genomes, with more off-target A>G SNVs forming after the ABEs had integrated into the genome. Furthermore, we detect off-target A>G RNA mutations in plants with high expression of ABEs but not in plants with low expression of ABEs. The off-target A>G RNA mutations tend to cluster, while off-target A>G DNA mutations rarely clustered. Conclusion Our findings that Cas proteins, TadA variants, temporal expression of ABEs, and expression levels of ABEs contribute to ABE specificity in rice provide insight into the specificity of ABEs and suggest alternative ways to increase ABE specificity besides engineering TadA variants.

As the most common RNA cap in eukaryotes, the 7-methylguanosine (m 7 G) cap impacts nearly all processes that a messenger RNA undergoes, such as splicing, polyadenylation, nuclear export, translation, and degradation. The metabolite and redox agent, nicotinamide adenine diphosphate (NAD + ), can be used as an initiating nucleotide in RNA synthesis to result in NAD + -capped RNAs. Such RNAs have been identified in bacteria, yeast, and human cells, but it is not known whether they exist in plant transcriptomes. The functions of the NAD + cap in RNA metabolism or translation are still poorly understood. Here, through NAD captureSeq, we show that NAD + -capped RNAs are widespread in Arabidopsis thaliana . NAD + -capped RNAs are predominantly messenger RNAs encoded by the nuclear and mitochondrial genomes, but not the chloroplast genome. NAD + -capped transcripts from the nuclear genome appear to be spliced and polyadenylated. Furthermore, although NAD + -capped transcripts constitute a small proportion of the total transcript pool from any gene, they are enriched in the polysomal fraction and associate with translating ribosomes. Our findings implicate the existence of as yet unknown mechanisms whereby the RNA NAD + cap interfaces with RNA metabolic processes as well as translation initiation. More importantly, our findings suggest that cellular metabolic and/or redox states may influence, or be regulated by, mRNA NAD + capping.

Epigenetic markers, such as histone acetylation and DNA methylation, determine chromatin organization. In eukaryotic cells, metabolites from organelles or the cytosol affect epigenetic modifications. However, the relationships between metabolites and epigenetic modifications are not well understood in plants. We found that peroxisomal acyl-CoA oxidase 4 (ACX4), an enzyme in the fatty acid β-oxidation pathway, is required for suppressing the silencing of some endogenous loci, as well as Pro35S : NPTII in the ProRD29A:LUC /C24 transgenic line. The acx4 mutation reduces nuclear histone acetylation and increases DNA methylation at the NOS terminator of Pro35S : NPTII and at some endogenous genomic loci, which are also targeted by the demethylation enzyme REPRESSOR OF SILENCING 1 (ROS1). Furthermore, mutations in multifunctional protein 2 (MFP2) and 3-ketoacyl-CoA thiolase-2 (KAT2/PED1/PKT3), two enzymes in the last two steps of the β-oxidation pathway, lead to similar patterns of DNA hypermethylation as in acx4 . Thus, metabolites from fatty acid β-oxidation in peroxisomes are closely linked to nuclear epigenetic modifications, which may affect diverse cellular processes in plants.

Due to their high theoretical capacities and high energy densities, metal fluorides have attracted significant attention as cathodes for lithium-ion batteries. However, thus far, their low conductivities have limited the performance of these materials. In this work, the Fe(1−x)Co x F3/MWCNT (multi-walled carbon nanotube) nanocomposites (x = 0, 0.02, 0.04 and 0.06) are obtained by an in situ solvothermal method with Co-doping and wrapping of the MWCNTs. The results indicate that Co-doping can adjust the crystal structure, decrease the band gaps and enhance the Li+ diffusion coefficient of FeF3. Additionally, the wrapped network of MWCNTs enhances the conductivity of the composites and improves their electrochemical performances. The Fe0.96Co0.04F3/MWCNT nanocomposites exhibit a high initial discharge capacity of 217.0 mAh g−1 at rate of 0.2 C within the potential range of 2.0–4.5 V, which is much higher than that of the FeF3/MWCNT counterpart (192.1 mAh g−1). The discharge capacities of these two samples remain at 187.9 and 160.7 mAh g−1 even after 50 cycles. Meanwhile, the EIS results reveal that both the Li+ charge transfer resistance (R ct = 31.25 Ω) and Li+ diffusion coefficient (1.40 × 10−11 cm2 s−1) are satisfactory from Co-doping and the in situ wrapping of the MWCNTs.

ᅟ Ag-coated spherical Li4Ti5O12 composite was successfully synthesized via a sol-gel-assisted hydrothermal method using an ethylene glycol and silver nitrate mixture as the precursor, and the influence of the Ag coating contents on the electrochemical properties of its was extensively investigated. X-ray diffraction (XRD) analysis indicated that the Ag coating does not change the spinel structure of Li4Ti5O12. The electrochemical impedance spectroscopy (EIS) analyses demonstrated that the excellent electrical conductivity of the Li4Ti5O12/Ag resulted from the presence of the highly conducting silver coating layer. Additionally, the nano-thick silver layer, which was uniformly coated on the particles, significantly improved this material’s rate capability. As a consequence, the silver-coated micron-sized spherial Li4Ti5O12 exhibited excellent electrochemical performance. Thus, with an appropriate silver content of 5 wt.%, the Li4Ti5O12/Ag delivered the highest capacity of 186.34 mAh g−1 at 0.5C, which is higher than that of other samples, and maintained 92.69% of its initial capacity at 5C after 100 cycles. Even at 10C after 100 cycles, it still had a capacity retention of 89.17%, demonstrating remarkable cycling stability. Trial registration ISRCTN NARL-D-17-00568

A Cr3+ and F− composite-doped LiNi0.5Mn1.5O4 cathode material was synthesized by the solid-state method, and the influence of the doping amount on the material’s physical and electrochemical properties was investigated. The structure and morphology of the cathode material were characterized by XRD, SEM, TEM, and HRTEM, and the results revealed that the sample exhibited clear spinel features. No Cr3+ and F− impurity phases were found, and the spinel structure became more stable. The results of the charge/discharge tests, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) test results suggested that LiCr0.05Ni0.475Mn1.475O3.95F0.05 in which the Cr3+ and F− doping amounts were both 0.05, had the optimal electrochemical properties, with discharge rates of 0.1, 0.5, 2, 5, and 10 C and specific capacities of 134.18, 128.70, 123.62, 119.63, and 97.68 mAh g−1 , respectively. After 50 cycles at a rate of 2 C, LiCr0.05Ni0.475Mn1.475O3.95F0.05 showed extremely good cycling performance, with a discharge specific capacity of 121.02 mAh g−1 and a capacity retention rate of 97.9%. EIS test revealed that the doping clearly decreased the charge-transfer resistance.

A novel and highly sensitive sensor for gaseous n-hexane utilizing the sensing material Y2O3–Al2O3 (mass ratio of 2 : 1) has been developed based on the thermal desorption/cataluminescence (TD/CTL). Firstly, the cataluminescence characteristics of the above sensor were investigated. Then, the optimal conditions of the developed sensor for the determination of n-hexane were analyzed using response surface methodology (RSM). When the sensor was performed at the optimal catalytic temperature (Tc) of 200 °C and the wavelength of 400 nm, the linear range was 1.32–132 mg m−3 with a detection limit of 0.4 mg m−3. In addition, there was little to no response when contaminating volatile substances including benzene, toluene, chloroform, ethanol, and cyclohexane were passed through the sensor. This proposed TD/CTL-based n-hexane sensor shows high sensitivity, good stability, and rapid response and allows real time monitoring of n-hexane in air.

A facile and effective sensor array consisting of three cataluminescence (CTL) sensors based on nanomaterial Y(2)O(3), γ-Al(2)O(3) and ZrO(2) as probes was firstly proposed for the molecular recognition and quantitative analysis of xylene isomers. Under the optimized conditions, the linear range of CTL intensity versus concentration of xylene isomers was 86.70-8670.00 mg m(-3). The use of a sensor array instead of a single sensor has provided a novel strategy for the process of identifying similar chemical compounds, which should have a bright future in environmental and industrial monitoring.

A highly sensitive gas sensor based on thermal desorption coupled with cataluminescence (TD/CTL) using TiO 2 -Y 2 O 3 (mass ratio 1:3) as a probe was firstly proposed for the determination of formaldehyde in air. Quantitative analysis was performed at an optimal adsorbent of active carbon, thermal desorption temperature of 140 °C, catalytic temperature of 195 °C, a wavelength of 490 nm and a flow rate of 280 mL/min. The linear range of CTL intensity versus concentration of formaldehyde was 0.026–1.30 mg/m 3 ( r = 0.9990, n = 7), and the detection limit (3 σ ) was 0.01 mg/m 3 . There was no or weak response to foreign substances, such as benzene, ethanol, chloroform, carbon tetrachloride, toluene, dimethylbenzene and n -hexane. This proposed formaldehyde gas sensor showed the high sensitivity, rapid response, good stability, and allowed on-line monitoring of formaldehyde in air.

The flower is a hallmark feature that has contributed to the evolutionary success of land plants. Diverse mutagenic agents have been employed as a tool to genetically perturb flower development and identify genes involved in floral patterning and morphogenesis. Since the initial studies to identify genes governing processes such as floral organ specification, mutagenesis in sensitized backgrounds has been used to isolate enhancers and suppressors to further probe the molecular basis of floral development. Here, we first describe two commonly employed methods for mutagenesis (using ethyl methanesulfonate (EMS) or T-DNAs as mutagens), and then describe three methods for identifying a mutation that leads to phenotypic alterations--traditional map-based cloning, TAIL-PCR, and deep sequencing in the plant model Arabidopsis thaliana.

RNA-directed DNA methylation (RdDM) and histone H3 lysine 9 dimethylation (H3K9me2) are related transcriptional silencing mechanisms that target transposable elements (TEs) and repeats to maintain genome stability in plants. RdDM is mediated by small and long noncoding RNAs produced by the plant-specific RNA polymerases Pol IV and Pol V, respectively. Through a chemical genetics screen with a luciferase-based DNA methylation reporter, LUCL, we found that camptothecin, a compound with anti-cancer properties that targets DNA topoisomerase 1α (TOP1α) was able to de-repress LUCL by reducing its DNA methylation and H3K9me2 levels. Further studies with Arabidopsis top1α mutants showed that TOP1α silences endogenous RdDM loci by facilitating the production of Pol V-dependent long non-coding RNAs, AGONAUTE4 recruitment and H3K9me2 deposition at TEs and repeats. This study assigned a new role in epigenetic silencing to an enzyme that affects DNA topology., Author Summary DNA topoisomerase is an enzyme that releases the torsional stress in DNA generated during DNA replication or transcription. Here, we uncovered an unexpected role of DNA topoisomerase 1α (TOP1α) in the maintenance of genome stability. Eukaryotic genomes are usually littered with transposable elements (TEs) and repeats, which pose threats to genome stability due to their tendency to move or recombine. Mechanisms are in place to silence these elements, such as RNA-directed DNA methylation (RdDM) and histone H3 lysine 9 dimethylation (H3K9me2) in plants. Two plant-specific RNA polymerases, Pol IV and Pol V, generate small and long noncoding RNAs, respectively, from TEs and repeats. These RNAs then recruit protein factors to deposit DNA methylation or H3K9me2 to silence the loci. In this study, we found that treatment of plants with camptothecin, a TOP1α inhibitor, or loss of function in TOP1α, led to the de-repression of RdDM target loci, which was accompanied by loss of H3K9me2 or DNA methylation. The role of TOP1α in RdDM could be attributed to its promotion of Pol V, but not Pol IV, transcription to generate long noncoding RNAs.

A highly sensitive and selective thermal desorption/cataluminescence (TD/CTL) sensor was developed for the determination of trichloroethylene (TCE) gas for the first time based on catalytic chemiluminescence (CTL) of TCE on ZnO–Y2O3 (mass ratio, 2 : 1) nanocomposites. The CL intensity was linear to the concentration of TCE gas in the range from 14.7 to 586.0 mg m−3 (r = 0.9958, n = 9) with a detection limit of 4.9 mg m−3 (the signal-to-noise ratio was 3) when the sensor was performed at the optimal temperature of 210 °C and wavelength of 440 nm. The sensor features the advantages of simple construction, rapid analysis, long life-time and high selectivity for TCE gas detection, and it has been applied to the online analysis of TCE gas.