A Eu-metal organic framework (Eu-MOF) probe with dual-emission was reported for the ratiometric fluorescence detection of H
O
and glucose. Because of the special nucleophilic reaction between boric ...group and H
O
, Eu
and 5-boronobenzene-1,3-dicarboxylic acid (BBDC) were selected to synthesize the functional MOF probe via a simple one-pot solvothermal method. The Eu-MOF shows dual-emission at 370 and 623 nm with the single excitation at 270 nm due to the energy transfer efficiency change for antenna effect procedure. After addition of H
O
, the red emission of Eu-MOF weakened and the blue emission enhances immediately under 270 nm irradiation, so the ratiometric fluorescence detection is established. Moreover, the obvious color change for visual measuring of H
O
and glucose is illustrated to reveal the merit of Eu-MOF probe. The proposed method was demonstrated to be highly sensitive and selective for H
O
and glucose, with the low detection limits of 0.0335 and 0.0643 μM, respectively. The established boric-acid-functional Eu-MOF sensing platform was proved as the powerful probe for H
O
and the metabolites involved in H
O
-generating reaction.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Fluorescence significantly improves the performance of gels. Various strategies, such as embedment and crosslinking, have been used to integrate extrinsic luminophores into gel systems, but the ...procedures are usually complex. Herein, for the first time, we report gels with intrinsic and tunable emission color prepared with 5-boronoisophthalic acid (5-bop) and Eu
, Tb
, and/or Dy
similar to the procedure for the preparation of metal-organic frameworks (MOFs). The single-metal gels exhibit intrinsic trichromatic fluorescence, due to which full-color emissions are readily obtained by tuning the type and/or ratio of Ln
ions to prepare mixed-metal gels. The emission is governed by an antenna effect and is thus excited with single-wavelength at 275 nm. The nucleation-growth mechanism reveals that the Ln
ions and 5-bop produce separated layers, which then grow anisotropically to form nanoribbons by high coordinated valence of Ln
ions and biased carboxyl distribution as well as steric hindrance and hydrogen bonds of the boric acid group in 5-bop. The nanoribbons entangle together to generate chemical-physical hybrid gels. To the best of our knowledge, this is the first example of gels with inherent and tunable emission color. Due to their optical and viscoelastic properties, the gels have numerous potential applications such as tunable emission and multi-target detection.
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IJS, KILJ, NUK, UL, UM, UPUK
Lignin biosynthesis is regulated by many transcription factors, such as those of the MYB and NAC families. However, the roles of AP2/ERF transcription factors in lignin biosynthesis have been rarely ...investigated. Eighteen EjAP2/ERF genes were isolated from loquat fruit (Eriobotrya japonica), which undergoes postharvest lignification during low temperature storage. Among these, expression of EjAP2‐1, a transcriptional repressor, was negatively correlated with fruit lignification. The dual‐luciferase assay indicated that EjAP2‐1 could trans‐repress activities of promoters of lignin biosynthesis genes from both Arabidopsis and loquat. However, EjAP2‐1 did not interact with the target promoters (Ej4CL1). Yeast two‐hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays indicated protein–protein interactions between EjAP2‐1 and lignin biosynthesis‐related EjMYB1 and EjMYB2. Furthermore, repression effects on the Ej4CL1 promoter were observed with the combination of EjAP2‐1 and EjMYB1 or EjMYB2, while EjAP2‐1 with the EAR motif mutated (mEjAP2‐1) lost such repression, although mEjAP2‐1 still interacted with EjMYB protein. Based on these results, it is proposed that EjAP2‐1 is an indirect transcriptional repressor on lignin biosynthesis, and the repression effects were manifested by EAR motifs and were conducted via protein–protein interaction with EjMYBs.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Summary
Chlorophyll degradation naturally occurs during plant senescence. However, in fruit such as citrus, it is a positive characteristic, as degreening is an important colour development ...contributing to fruit quality. In the present work, Citrus sinensis Osbeck, cv. Newhall fruit was used as a model for chlorophyll degradation. An ethylene response factor, CitERF13, was isolated and its transcriptional changes were closely correlated with fruit peel degreening during development or in response to ethylene. Dual‐luciferase and yeast one‐hybrid assays, as well as motif mutation, indicated that CitERF13 directly binds to the CitPPH promoter and enhances its activity. Transient and stable over‐expression of CitERF13 resulted in rapid chlorophyll degradation in Nicotiana tabacum leaves and led to accumulation of pheophorbide (Pheide) a, a metabolite of pheophorbide hydrolase (PPH). Similar results were observed from transient transformation of CitERF13 in citrus fruit peel. Moreover, this function of CitERF13 was conserved within Arabidopsis and tomato, as the homologs AtERF17 and SlERF16 similarly acted as activators of PPH genes and accelerators of chlorophyll degradation.
Significance Statement
Chlorophyll degradation in the fruit is a desired trait in citrus, so understanding the underlying molecular mechanisms is important for citrus breeding. Here we show that an ethylene response factor directly binds to the promoter of PPH, a gene encoding pheohorbide hydrolase, a key mark of chlorophyll degradation.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Low temperature conditioning (LTC) alleviates peach fruit chilling injury but the underlying molecular basis is poorly understood. Here, changes in transcriptome, ethylene production, flesh ...softening, internal browning and membrane lipids were compared in fruit maintained in constant 0 °C and LTC (pre‐storage at 8 °C for 5 d before storage at 0 °C). Low temperature conditioning resulted in a higher rate of ethylene production and a more rapid flesh softening as a result of higher expression of ethylene biosynthetic genes and a series of cell wall hydrolases. Reduced internal browning of fruit was observed in LTC, with lower transcript levels of polyphenol oxidase and peroxidase, but higher lipoxygenase. Low temperature conditioning fruit also showed enhanced fatty acid content, increased desaturation, higher levels of phospholipids and a preferential biosynthesis of glucosylceramide. Genes encoding cell wall hydrolases and lipid metabolism enzymes were coexpressed with differentially expressed ethylene response factors (ERFs) and contained ERF binding elements in their promoters. In conclusion, LTC is a special case of cold acclimation which increases ethylene production and, operating through ERFs, promotes both softening and changes in lipid composition and desaturation, which may modulate membrane stability, reducing browning and contributing to alleviation of peach fruit chilling injury.
Although cold stress responses in whole plants have been comprehensively studied, the mechanisms underlying postharvest chilling injury in fruit are still largely unknown. In this study, we show that the failure of normal fruit softening and internal browning in peach fruit can be relieved by low temperature conditioning, and this alleviation is accompanied by activation of ethylene biosynthesis, cell wall modification and many lipid adjustments, especially the selective biosynthesis of sphingolipids, which may contribute to membrane stability. Ethylene response factors play central roles in regulating these cold responses and potential target genes related to cell wall and lipid metabolism have been identified.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Heat stress is a major abiotic stress for plants, which can generate a range of biochemical and genetic responses. In ‘Ponkan’ mandarin fruit, hot air treatment (HAT) accelerates the degradation of ...citric acid. However, the transcriptional regulatory mechanisms of citrate degradation in response to HAT remain to be elucidated. Here, 17 heat shock transcription factor sequences were isolated, and dual‐luciferase assays were employed to investigate whether the encoded proteins that could trans‐activate the promoters of key genes in the GABA shunt, involved in citrate metabolism. We identified four heat shock transcription factors (CitHsfA7, CitHsfA3, CitHsfA4b and CitHsfA8) that showed trans‐activation effects on CitAco3, CitIDH3 and CitGAD4, respectively. Transient expression of the CitHsfs in citrus fruits indicated that CitHsfA7 was the only factor that resulted in a significant lowering of the citric acid content, and these results were confirmed by a virus‐induced gene silencing system (VIGS). Sub‐cellar localization showed that CitHsfA7 is located in the nucleus and is capable of binding directly to a putative HSE in the CitAco3 promoter and enhance its expression. We proposed that the induction of CitHsfA7 transcript level contributes to citric acid degradation in citrus fruit, via modulation of CitAco3 in response to HAT.
A heat shock transcription factor CitHsfA7 was characterized in citrus, which accelerates citric acid degradation via transcriptional regulating the aconitase gene (CitAco3) in response to heat stress. CitHsfA7 can be considered a key regulator mediating the role of heat treatment on citric acid degradation.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Chrysanthemums (Chrysanthemum morifolium Ramat.) exhibit a variety of flower colors due to their differing abilities to accumulate anthocyanins. One MYB member, CmMYB6, has been verified as a ...transcription regulator of chrysanthemum genes involved in anthocyanin biosynthesis; however, the co-regulators for CmMYB6 remain unclear in chrysanthemum. Here, the expression pattern of CmbHLH2, which is clustered in the IIIf bHLH subgroup, was shown to be positively correlated with the anthocyanin content of cultivars with red, pink and yellow flower colors, respectively. CmbHLH2 significantly upregulated the CmDFR promoter and triggered anthocyanin accumulation when co-expressed with CmMYB6. Yeast one-hybrid analyses indicated that CmbHLH2 was able to bind directly to the CmDFR promoter. Moreover, yeast two-hybrid assays indicated protein-protein interaction between CmbHLH2 and CmMYB6. These results suggest that CmbHLH2 is the essential partner for CmMYB6 in regulating anthocyanin biosynthesis in chrysanthemum.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The combination of multidrug chemotherapy and photothermal therapy (PTT) enhances cancer therapeutic efficacy. Herein, we develop a simple and smart pH/NIR dual-stimulus-responsive degradable ...mesoporous CoFe2O4@PDA@ZIF-8 sandwich nanocomposite. The mesoporous CoFe2O4 core acts as T2-weighted magnetic resonance (MR) imaging probe, PTT agent, and loading platform of hydrophilic doxorubicin (DOX). A polydopamine (PDA) layer is used to avoid the premature leakage of DOX before arriving at tumor site, enhance PTT efficiency, and facilitate the integration of ZIF-8 (a kind of metal–organic framework). The ZIF-8 shell serves to encapsulate hydrophobic camptothecin (CPT) and as the switch for the pH and NIR stimulation-responsive release of the two drugs. Therefore, T2-weighted MR imaging-guided multidrug chemotherapy and PTT synergistic treatment is achieved. Two kinds of anticancer drugs, hydrophilic DOX and hydrophobic CPT, are successfully loaded in CoFe2O4 and ZIF-8, respectively, so no mutual interference between the two drugs exists. A unique two-stage stepwise release process is exhibited for CPT and DOX with an interval of 12 h to improve the anticancer efficacy under the acidic microenvironment of tumor tissue. NIR irradiation achieves the burst drug-release and PTT after laser stimulation, simultaneously. With this smart design, high drug concentration is achieved at the tumor site by quick release, especially for the therapeutic drugs that show nonlinear pharmacokinetics, and PTT is integrated efficiently. Furthermore, negligible biotoxicity and a remarkable synergic antitumor effect of the hybrid nanocomposites are validated by HepG2 cells and tumor-bearing mice as models. Our multidrug delivery-releasing composite improves tumor therapeutic efficiency significantly compared with a single-drug chemotherapy system. The simple multifunctional composite system can be applied as an effective platform for personal nanomedicine with diagnosis, smart drug delivery, and cancer treatment through its remarkable photothermal property and controllable multidrug release.
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IJS, KILJ, NUK, PNG, UL, UM
Chinese bayberry (Myrica rubra Sieb. and Zucc.) is an important subtropical fruit crop and an ideal species for fruit quality research due to the rapid and substantial changes that occur during ...development and ripening, including changes in fruit color and taste. However, research at the molecular level is limited by a lack of sequence data. The present study was designed to obtain transcript sequence data and examine gene expression in bayberry developing fruit based on RNA-Seq and bioinformatic analysis, to provide a foundation for understanding the molecular mechanisms controlling fruit quality changes during ripening.
RNA-Seq generated 1.92 G raw data, which was then de novo assembled into 41,239 UniGenes with a mean length of 531 bp. Approximately 80% of the UniGenes (32,805) were annotated against public protein databases, and coding sequences (CDS) of 31,665 UniGenes were determined. Over 3,600 UniGenes were differentially expressed during fruit ripening, with 826 up-regulated and 1,407 down-regulated. GO comparisons between the UniGenes of these two types and interactive pathways (Ipath) analysis found that energy-related metabolism was enhanced, and catalytic activity was increased. All genes involved in anthocyanin biosynthesis were up-regulated during the fruit ripening processes, concurrent with color change. Important changes in carbohydrate and acid metabolism in the ripening fruit are likely associated with expression of sucrose phosphate synthase (SPS) and glutamate decarboxylase (GAD).
Mass sequence data of Chinese bayberry was obtained and the expression profiles were examined during fruit ripening. The UniGenes were annotated, providing a platform for functional genomic research with this species. Using pathway mapping and expression profiles, the molecular mechanisms for changes in fruit color and taste during ripening were examined. This provides a reference for the study of complicated metabolism in non-model perennial species.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Transcriptional regulatory mechanisms underlying lignin metabolism have been widely studied in model plants and woody trees, as well as fruit, such as loquat (Eriobotrya japonica). Unlike the ...well‐known NAC, MYB and AP2/ERF transcription factors, the roles of heat shock factors (HSFs) in lignin regulation have been rarely reported. Two treatments (heat treatment, HT; low temperature conditioning, LTC) were applied to alleviate low temperature‐induced lignification in loquat fruit. Gene expression analysis indicated that EjHSF1 transcript abundance, in parallel with heat shock protein genes (EjHsp), was induced by HT, while expression of EjHSF3 was repressed by LTC. Using dual‐luciferase assays, EjHSF1 and EjHSF3 trans‐activated the promoters of EjHsp genes and lignin biosynthesis‐related genes, respectively. Thus, two distinct regulatory mechanisms of EjHSF transcription factors in chilling injury‐induced fruit lignification are proposed: EjHSF1 transcriptionally regulated EjHsp genes are involved in chilling tolerance, while EjHSF3 transcriptionally regulated lignin biosynthesis. Furthermore, the relations between EjHSF3 and previously characterized fruit lignification regulators, including EjAP2‐1, EjMYB1 and EjMYB2, were also investigated. Yeast‐two hybrid (Y2H) and biomolecular fluorescence complementation (BiFC) assays demonstrated protein‐protein interaction between EjHSF3 and EjAP2‐1. Thus, the involvement of EjHSF3 in fruit lignification is via both lignin biosynthetic genes and the regulator, EjAP2‐1.
Fruit may be subject to chilling injury during postharvest low temperature storage, and heat treatments have been shown to alleviate chilling injury symptoms in many fruit species. The present research showed that heat shock factors (HSF) are involved in loquat fruit chilling injury and induced lignification via two distinct pathways. EjHSF1 transcriptionally regulated EjHsp genes, while EjHSF3 interacted with EjAP2‐1 and regulated lignin biosynthetic genes.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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