Genomic imprinting is a form of epigenetic regulation resulting in differential gene expression that reflects the parent of origin. In plants, imprinted gene expression predominantly occurs in the seed endosperm. Maternal-specific DNA demethylation by the DNA demethylase DME frequently underlies genomic imprinting in endosperm. Whether other more ubiquitously expressed DNA demethylases regulate imprinting is unknown. Here, we found that the DNA demethylase ROS1 regulates the imprinting of DOGL4. DOGL4 is expressed from the maternal allele in endosperm and displays preferential methylation and suppression of the paternal allele. We found that ROS1 negatively regulates imprinting by demethylating the paternal allele, preventing its hypermethylation and complete silencing. Furthermore, we found that DOGL4 negatively affects seed dormancy and response to the phytohormone abscisic acid and that ROS1 controls these processes by regulating DOGL4. Our results reveal roles for ROS1 in mitigating imprinted gene expression and regulating seed dormancy.

BackgroundSimilar to common buckwheat (Fagopyrum esculentum), tartary buckwheat (Fagopyrum tataricum) shows a high level of aluminum (Al) tolerance and accumulation. However, the molecular mechanisms for Al detoxification and accumulation are still poorly understood. To begin to elucidate the molecular basis of Al tolerance and accumulation, we used the Illumina high-throughput mRNA sequencing (RNA-seq) technology to conduct a genome-wide transcriptome analysis on both tip and basal segments of the roots exposed to Al.ResultsBy using the Trinity method for the de novo assembly and cap3 software to reduce the redundancy and chimeras of the transcripts, we constructed 39,815 transcripts with an average length of 1184 bp, among which 20,605 transcripts were annotated by BLAST searches in the NCBI non-redundant protein database. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that expression of genes involved in the defense of cell wall toxicity and oxidative stress was preferentially induced by Al stress. Our RNA-seq data also revealed that organic acid metabolism was unlikely to be a rate-limiting step for the Al-induced secretion of organic acids in buckwheat. We identified two citrate transporter genes that were highly induced by Al and potentially involved in the release of citrate into the xylem. In addition, three of four conserved Al-tolerance genes were found to be duplicated in tartary buckwheat and display diverse expression patterns.ConclusionsNearly 40,000 high quality transcript contigs were de novo assembled for tartary buckwheat, providing a reference platform for future research work in this plant species. Our differential expression and phylogenetic analysis revealed novel aspects of Al-tolerant mechanisms in buckwheat.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0395-z) contains supplementary material, which is available to authorized users.

Tang W-Z and Li F-L (2020) Energy Conservation and Carbon Flux Distribution During Fermentation of CO or H 2 /CO 2 by Clostridium ljungdahlii.

ABSTRACT Bioethanol production from syngas using acetogenic bacteria has attracted considerable attention in recent years. However, low ethanol yield is the biggest challenge that prevents the commercialization of syngas fermentation into biofuels using microbial catalysts. The present study demonstrated that ethanol metabolism plays an important role in recycling NADH/NAD+ during autotrophic growth. Deletion of bifunctional aldehyde/alcohol dehydrogenase (adhE) genes leads to significant growth deficiencies in gas fermentation. Using specific fermentation technology in which the gas pressure and pH were constantly controlled at 0.1 MPa and 6.0, respectively, we revealed that ethanol was formed during the exponential phase, closely accompanied by biomass production. Then, ethanol was oxidized to acetate via the aldehyde ferredoxin oxidoreductase pathway in Clostridium ljungdahlii. A metabolic experiment using 13C-labeled ethanol and acetate, redox balance analysis, and comparative transcriptomic analysis demonstrated that ethanol production and reuse shared the metabolic pathway but occurred at different growth phases. IMPORTANCE Ethanol production from carbon monoxide (CO) as a carbon and energy source by Clostridium ljungdahlii and “Clostridium autoethanogenum” is currently being commercialized. During gas fermentation, ethanol synthesis is NADH-dependent. However, ethanol oxidation and its regulatory mechanism remain incompletely understood. Energy metabolism analysis demonstrated that reduced ferredoxin is the sole source of NADH formation by the Rnf-ATPase system, which provides ATP for cell growth during CO fermentation. Therefore, ethanol production is tightly linked to biomass production (ATP production). Clarification of the mechanism of ethanol oxidation and biosynthesis can provide an important reference for generating high-ethanol-yield strains of C. ljungdahlii in the future.

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Conductive multilayer films have been fabricated from the alternating adsorption of the charged polymers, polypyrrole (PPy) and polyallylamine hydrochloride (PAH), on planar substrates as well as onto the surfaces of melamine formaldehyde (MF) microparticles based on the sequenced electrostatic layer-by-layer assembly technique. Hollow microcapsules are achieved after the removal of MF cores by dissolution in acid solution. The structure and conductive properties of the multilayer films and the hollow shells were characterized by UV−visible spectroscopy, phase contrast optical microscopy, atomic force microscopy, transmission electron microscopy, and scanning electron microscopy, respectively. The conductivity of all the composite films calculated from the measured resistivity is about 0.007 S/cm, which is comparable to other conductive polyelectrolyte films. The measurement of cyclic voltammetry showed that the PPy/PAH planar multilayer films, PPy/PAH-modified colloid particles, and hollow shells maintained their oxidative stability and electrochemical properties.

Aurintricarboxylic acid (ATA), a UV absorbent, has successfully been intercalated into the interlayer spacing of ZnÀAlÀNO 3 -LDHs precursor through an anion-exchange reaction. The structure and the thermal-and photostability of the intercalated product were investigated by various techniques such as powder X-ray diffraction (XRD), infrared spectroscopy (FT-IR), thermogravimetry and differential thermal analysis (TGÀDTA), and UVÀvis spectroscopy. The increase of the basal spacing from 0.90 to 1.52 nm as observed by XRD suggests that the ATA anions have replaced the NO 3 À anions in the interlayer region of the precursor LDHs. The results of infrared spectroscopy and thermogravimetry and differential thermal analysis (TGÀDTA) also reveal the presence of supramolecular hostÀguest interactions between the brucite-like sheet and the intercalated ATA anions. The intercalation of the ATA anions into the LDHs markedly enhances the thermal stability of this UV absorbent. After incorporation of 1 wt % ZnAl-ATA-LDHs to polypropylene (PP), also, the resulted ZnAl-ATA-LDHs/PP composite has much higher resistance to UV degradation related to PP.

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