Summary
Anthocyanins have crucial biological functions and affect quality of horticultural produce. Anthocyanins accumulate in ripe peach fruit; differential accumulation is observed in deep coloured ...cultivar ‘Hujingmilu’ and lightly pigmented cultivar ‘Yulu’. The difference was not fully explained by accumulation of total flavonoids and expression of anthocyanin biosynthetic genes. Expression analysis was conducted on a glutathione S‐transferase gene (PpGST1), and it was found that the expression correlated well with anthocyanin accumulation in peach fruit tissues. Functional complementation of the Arabidopsis tt19 mutant indicated that PpGST1 was responsible for transport of anthocyanins but not proanthocyanidins. PpGST1 was localized in nuclei and the tonoplast, including the sites at which anthocyanin vacuolar sequestration occurred. Transient overexpression of PpGST1 together with PpMYB10.1 in tobacco leaves and peach fruit significantly increased anthocyanin accumulation as compared with PpMYB10.1 alone. Furthermore, virus‐induced gene silencing of PpGST1 in a blood‐fleshed peach not only resulted in a reduction in anthocyanin accumulation but also a decline in expression of anthocyanin biosynthetic and regulatory genes. Cis‐element analysis of the PpGST1 promoter revealed the presence of four MYB binding sites (MBSs). Dual‐luciferase assays indicated that PpMYB10.1 bound to the promoter and activated the transcription of PpGST1 by recognizing MBS1, the one closest to the ATG start codon, with this trans‐activation being stronger against the promoter of deep coloured ‘Hujingmilu’ compared with lightly coloured cultivar ‘Yulu’. Altogether, our data provided molecular evidence supporting coordinative regulatory roles of PpGST1 and PpMYB10.1 in anthocyanin accumulation in peach.
• Anthocyanin and proanthocyanidin (PA) accumulation is regulated by both myeloblastosis (MYB) activators and repressors, but little information is available on hierarchical interactions between the ...positive and negative regulators. Here, we report on a R2R3-MYB repressor in peach, designated PpMYB18, which acts as a negative regulator of anthocyanin and PA accumulation.
• PpMYB18 can be activated by both anthocyanin- and PA-related MYB activators, and is expressed both at fruit ripening and juvenile stages when anthocyanins or PAs, respectively, are being synthesized.
• The PpMYB18 protein competes with MYB activators for binding to basic Helix Loop Helixes (bHLHs), which develops a fine-tuning regulatory loop to balance PA and anthocyanin accumulation. In addition, the bHLH binding motif in the R3 domain and the C1 and C2 repression motifs in the C-terminus of PpMYB18 both confer repressive activity of PpMYB18.
• Our study also demonstrates a modifying negative feedback loop, which prevents cells from excess accumulation of anthocyanin and PAs, and serves as a model for balancing secondary metabolite accumulation at the transcriptional level.
Anthocyanin pigmentation is an important consumer trait in peach (Prunus persica). In this study, the genetic basis of the blood‐flesh trait was investigated using the cultivar Dahongpao, which shows ...high levels of cyanidin‐3‐glucoside in the mesocarp. Elevation of anthocyanin levels in the flesh was correlated with the expression of an R2R3 MYB transcription factor, PpMYB10.1. However, PpMYB10.1 did not co‐segregate with the blood‐flesh trait. The blood‐flesh trait was mapped to a 200‐kb interval on peach linkage group (LG) 5. Within this interval, a gene encoding a NAC domain transcription factor (TF) was found to be highly up‐regulated in blood‐fleshed peaches when compared with non‐red‐fleshed peaches. This NAC TF, designated BLOOD (BL), acts as a heterodimer with PpNAC1 which shows high levels of expression in fruit at late developmental stages. We show that the heterodimer of BL and PpNAC1 can activate the transcription of PpMYB10.1, resulting in anthocyanin pigmentation in tobacco. Furthermore, silencing the BL gene reduces anthocyanin pigmentation in blood‐fleshed peaches. The transactivation activity of the BL‐PpNAC1 heterodimer is repressed by a SQUAMOSA promoter‐binding protein‐like TF, PpSPL1. Low levels of PpMYB10.1 expression in fruit at early developmental stages is probably attributable to lower levels of expression of PpNAC1 plus the presence of high levels of repressors such as PpSPL1. We present a mechanism whereby BL is the key gene for the blood‐flesh trait in peach via its activation of PpMYB10.1 in maturing fruit. Partner TFs such as basic helix–loop‐helix proteins and NAC1 are required, as is the removal of transcriptional repressors.
Summary
Anthocyanins are visual cues for pollination and seed dispersal. Fruit containing anthocyanins also appeals to consumers due to its appearance and health benefits. In kiwifruit (Actinidia ...spp.) studies have identified at least two MYB activators of anthocyanin, but their functions in fruit and the mechanisms by which they act are not fully understood.
Here, transcriptome and small RNA high‐throughput sequencing were used to comprehensively identify contributors to anthocyanin accumulation in kiwifruit.
Stable overexpression in vines showed that both 35S::MYB10 and MYB110 can upregulate anthocyanin biosynthesis in Actinidia chinensis fruit, and that MYB10 overexpression resulted in anthocyanin accumulation which was limited to the inner pericarp, suggesting that repressive mechanisms underlie anthocyanin biosynthesis in this species. Furthermore, motifs in the C‐terminal region of MYB10/110 were shown to be responsible for the strength of activation of the anthocyanic response. Transient assays showed that both MYB10 and MYB110 were not directly cleaved by miRNAs, but that miR828 and its phased small RNA AcTAS4‐D4(−) efficiently targeted MYB110. Other miRNAs were identified, which were differentially expressed between the inner and outer pericarp, and cleavage of SPL13, ARF16, SCL6 and F‐box1, all of which are repressors of MYB10, was observed.
We conclude that it is the differential expression and subsequent repression of MYB activators that is responsible for variation in anthocyanin accumulation in kiwifruit species.
Summary
Anthocyanin biosynthesis is induced by low temperatures in a number of plants. However, in peach (cv Zhonghuashoutao), anthocyanin accumulation was observed in fruit stored at 16°C but not at ...or below 12°C. Fruit stored at 16°C showed elevated transcript levels of genes encoding anthocyanin biosynthetic enzymes, the transport protein glutathione S‐transferase and key transcription factors. Higher transcript levels of PpPAL1/2, PpC4H, Pp4CL4/5/8, PpF3H, PpF3’H, PpDFR1/2/3 and PpANS, as well as transcription factor gene PpbHLH3, were associated with lower methylation levels in the promoter of these genes. The DNA methylation level was further highly correlated with the expression of the DNA methyltransferase genes and DNA demethylase genes. The application of DNA methylation inhibitor 5‐azacytidine induced anthocyanin accumulation in peach flesh, further implicating a critical role for DNA demethylation in regulating anthocyanin accumulation in peach flesh. Our data reveal that temperature‐dependent DNA demethylation is a key factor to the post‐harvest temperature‐dependent anthocyanin accumulation in peach flesh.
Significance Statement
Anthocyanin accumulates at 16°C but not below 12°C in an originally white‐fleshed peach cultivar, accompanied by a global increase in transcript levels of anthocyanin biosynthetic and transcription factor genes. Elevated transcript levels are associated with decreases in DNA methylation as a result of regulating expression of DNA methyltransferase and DNA demethylase genes. The involvement of DNA demethylation in induction of anthocyanin accumulation was further confirmed using fruit treated with the DNA methylation inhibitor 5‐azacytidine.
High-temperature sodium-sulfur batteries operating at 300-350 °C have been commercially applied for large-scale energy storage and conversion. However, the safety concerns greatly inhibit their ...widespread adoption. Herein, we report a room-temperature sodium-sulfur battery with high electrochemical performances and enhanced safety by employing a "cocktail optimized" electrolyte system, containing propylene carbonate and fluoroethylene carbonate as co-solvents, highly concentrated sodium salt, and indium triiodide as an additive. As verified by first-principle calculation and experimental characterization, the fluoroethylene carbonate solvent and high salt concentration not only dramatically reduce the solubility of sodium polysulfides, but also construct a robust solid-electrolyte interface on the sodium anode upon cycling. Indium triiodide as redox mediator simultaneously increases the kinetic transformation of sodium sulfide on the cathode and forms a passivating indium layer on the anode to prevent it from polysulfide corrosion. The as-developed sodium-sulfur batteries deliver high capacity and long cycling stability.
The control of plant anthocyanin accumulation is via transcriptional regulation of the genes encoding the biosynthetic enzymes. A key activator appears to be an R2R3 MYB transcription factor. In ...apple fruit, skin anthocyanin levels are controlled by a gene called MYBA or MYB1, while the gene determining fruit flesh and foliage anthocyanin has been termed MYB10. In order to further understand tissue-specific anthocyanin regulation we have isolated orthologous MYB genes from all the commercially important rosaceous species.
We use gene specific primers to show that the three MYB activators of apple anthocyanin (MYB10/MYB1/MYBA) are likely alleles of each other. MYB transcription factors, with high sequence identity to the apple gene were isolated from across the rosaceous family (e.g. apples, pears, plums, cherries, peaches, raspberries, rose, strawberry). Key identifying amino acid residues were found in both the DNA-binding and C-terminal domains of these MYBs. The expression of these MYB10 genes correlates with fruit and flower anthocyanin levels. Their function was tested in tobacco and strawberry. In tobacco, these MYBs were shown to induce the anthocyanin pathway when co-expressed with bHLHs, while over-expression of strawberry and apple genes in the crop of origin elevates anthocyanins.
This family-wide study of rosaceous R2R3 MYBs provides insight into the evolution of this plant trait. It has implications for the development of new coloured fruit and flowers, as well as aiding the understanding of temporal-spatial colour change.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Shale gas stored in deep shale is in a supercritical state. Therefore, it is necessary to study the adsorption and desorption properties of supercritical shale gas. To accurately determine the state ...of methane (CH4) in the pores of deep shale, the fractal characteristics of several shale samples drilled at a depth of 2650 m are analyzed using scanning electron microscopy (SEM) and image analysis. We find nanopores with different fractal features in the shale. The effects of adsorption energy and substrate strain on adsorption capacity are clarified. The virial coefficients of CH4 are obtained by molecular dynamics (MD) simulations and are consistent with the experiment. The adsorption and desorption of CH4 in different fractal nanopores are modeled using grand canonical Monte Carlo (GCMC) simulations at different temperatures and pressures (from capillary condensation to supercritical state). Additionally, the gas-in-place (GIP), excess adsorption, and absolute adsorption isotherms are obtained. We find the crossover of excess adsorption isotherms, which was observed in the experiment, and the absolute adsorption amount increases with the increase in pressure in the case of ultrahigh pressure (>40 MPa). Moreover, we obtain an ultrahigh-pressure dual-site Langmuir equation, and it can accurately describe observed adsorption isotherms from low pressure to ultrahigh pressure. Our study visually reproduces the adsorption/desorption behaviors of CH4 under in situ conditions in deep shale and reveals their microscopic mechanism.
Preeclampsia (PE) accounts for the foremost cause of maternal and fetal mortality worldwide, whereas, there are no effective treatments for the disease yet. Long non-coding RNAs (lncRNAs) play ...critical roles in various human disorders, including PE. Here, we identified an up-regulated lncRNA HOTAIR, and explored its underlying mechanisms in PE.
qRT-PCR analysis was used to examine HOTAIR expression in PE tissues and cell lines. Trophoblast proliferation was examined by colony formation and 5-Ethynyl-2′-deoxyuridine (EdU) incorporation assays. Trophoblast migration and invasion was determined by transwell and wound healing assays. Bioinformatics analysis was performed to verify the regulation HOTAIR on miRNAs. The interaction between HOTAIR and EZH2 was detected using RNA immunoprecipitation assay (RIP). Chromatin immunoprecipitation (CHIP) assay was also performed to verify that the negative regulation of HOTAIR on miR-106a was dependent on the epigenetic repressor EZH2.
HOTAIR was up-regulated in PE placenta tissues, which repressed the proliferation, migration and invasion of trophoblast cells. HOTAIR significantly repressed miR-106a expression and the reduced miR-106a level was also observed in placentas from PE patients. Additionally, miR-106a mimic enhanced the migration and invasion of trophoblast cells. Further mechanistic analyses implied that the action of HOTAIR is moderately attributable to its repression of miR-106a via association with EZH2.
High level of HOTAIR repressed the proliferation, migration and invasion of trophoblast cells through targeting miR-106 in an EZH2-dependent manner, which may provide new insights into the roles of HOTAIR and miR-106a as potential regulators in PE.
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Understanding the role of pinning force in droplet dynamic wetting is of critical importance for surface science studies. Generally, the pinning force is only related to the surface ...tension and the change of contact angle. However, there is an obvious correlation between the pinning force and the surface geometry. In this paper, the relation between the surface geometry and contact line pinning was studied with systematical experiments and theoretical analysis. We compared the samples with different edge angles and carried out plenty experiments with different liquids. Meanwhile, the theoretical analysis and molecular simulation were carried out. The results show that the sharp edge has a strong pinning effect on the contact line and can significantly change the contact angle and wetting state of droplets. The maximum contact angle of droplet has a linear relation with the edge angle of substrate. The formula of pinning force was revised to consider the impact of surface topography. According to the relationship between surface defect and contact line, we proposed a model to classify the cases of contact line pinning for the first time. Our research will deepen the understanding of contact line pinning and provide help for potentially industrial production designs.
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