Ionic Porous Aromatic Frameworks Embedding Polyoxometalates for Heterogeneous Catalysis.

Porous aromatic frameworks (PAFs) are promising functional porous solids known for their feasible amenability and extraordinary stability. When the framework modified by ionic functional groups, the given ionic PAFs (iPAFs) exhibited charged channels for adsorption, separation and catalysis. However, the surface areas of ionic porous frameworks are usually lower than the neutral ones, and their synthesis limited by specific strategies and complex modifying processes. To overcome these problems, we proposed an intuitive route to construct ionic porous framework with high specific surface area, through a multivariable synthesis strategy. Herein, multivariate ionic porous aromatic framework (MTV-iPAFs) material named PAF-270 was synthesized from readily available building units with ionic functional groups. PAF-270 exhibited hierarchical structure with the highest specific surface area among reported imidazolium functionalized PAFs. Leveraging its physical and chemical properties, we explored its availability for polyoxometalates loading and heterogeneous catalysis. PAF-270 exhibited high adsorption capacity up to 50% for both H3O40PW12 (HPW) and (NH4)5H6PV8Mo4O40 (V8). HPW@PAF-270 and V8@PAF-270 exhibited excellent catalytic abilities for oleic acid esterification and extractive oxidative desulfurization, respectively. Due to the stability of PAFs, these materials also showed remarkable resistance to temperature and pH changes. These results highlight the potential application of MTV-iPAFs as functional porous materials.

Integrative lipidomics profile uncovers the mechanisms underlying high-level α-linolenic acid accumulation in Paeonia rockii seeds.

Tree peony (Paeonia rockii) is an excellent woody oilseed crop, known for its high α-linolenic acid (ALA, ~45%) content, which is of great value for human health. However, the mechanisms underlying this high-level ALA accumulation in tree peony seeds are poorly understood. In this study, we evaluated the dynamic changes in the lipidomic profile of P. rockii seeds during development. A total of 760 lipid molecules were identified in P. rockii seeds; triacylglycerol (TAG) lipid molecules showed the highest abundance and diversity, both increasing during seed development. Particularly, ALA was the predominant fatty acid at the TAG sn-3 position. We further characterized two diacylglycerol acyltransferase (DGAT) genes and three phospholipid:diacylglycerol acyltransferase (PDAT) genes involved in the transfer of fatty acids to the TAG sn-3 position. Gene expression and subcellular localization analyses suggested that PrDGATs and PrPDATs may function as endoplasmic reticulum-localized proteins in seed TAG biosynthesis. In vitro functional complementation analysis showed different substrate specificities, with PrPDAT2 having a specific preference for ALA. Multiple biological assays demonstrated that PrDGAT1, PrDGAT2, PrPDAT1-2, and PrPDAT2 promote oil synthesis. Specifically, PrPDAT2 leads to preferential ALA in the oil. Our findings provide novel functional evidence of the roles of PrDGAT1 and PrPDAT2, which are potential targets for increasing the ALA yield in tree peony and other oilseed crops.

Simultaneous removal of pharmaceuticals and heavy metals from aqueous phase via adsorptive strategy: A critical review.

The coexistence of pharmaceuticals and heavy metals is regarded as a serious threat to aquatic environments. Adsorbents have been widely applied to the simultaneous removal of pharmaceuticals and metals from aqueous phase. Through a comprehensive review, behaviors that promote, inhibit, or have no effect on simultaneous adsorption of pharmaceuticals and heavy metals were found to depend on the system of contaminants and adsorbents and their environmental conditions, such as: characteristics of adsorbent and pollutant, temperature, pH, inorganic ions, and natural organic matter. Bridging and competition effects are the main reasons for promoting and inhibiting adsorption in coexisting systems, respectively. The promotion is more significant in neutral or alkaline conditions. After simultaneous adsorption, a solvent elution approach was most commonly used for regeneration of saturated adsorbents. To conclude, this work could help to sort out the theoretical knowledge in this field, and may provide new insights into the prevention and control of pharmaceuticals and heavy metals coexisting in wastewater.

Diacylglycerol Acyltransferase 3(DGAT3) Is Responsible for the Biosynthesis of Unsaturated Fatty Acids in Vegetative Organs of Paeonia rockii.

'Diacylglycerol acyltransferase (DGAT)' acts as a key rate-limiting enzyme that catalyzes the final step of the de novo biosynthesis of triacylglycerol (TAG). The study was to characterize the function of the DGAT3 gene in Paeonia rockii, which is known for its accumulation of high levels of unsaturated fatty acids (UFAs). We identified a DGAT3 gene which encodes a soluble protein that is located within the chloroplasts of P. rockii. Functional complementarity experiments in yeast demonstrated that PrDGAT3 restored TAG synthesis. Linoleic acid (LA, C18:2) and α-linolenic acid (ALA, C18:3) are essential unsaturated fatty acids that cannot be synthesized by the human body. Through the yeast lipotoxicity test, we found that the yeast cell density was largely increased by adding exogenous LA and, especially, ALA to the yeast medium. Further ectopic transient overexpression in Nicotiana benthamiana leaf tissue and stable overexpression in Arabidopsis thaliana indicated that PrDGAT3 significantly enhanced the accumulation of the TAG and UFAs. In contrast, we observed a significant decrease in the total fatty acid content and in several major fatty acids in PrDGAT3-silenced tree peony leaves. Overall, PrDGAT3 is important in catalyzing TAG synthesis, with a substrate preference for UFAs, especially LA and ALA. These results suggest that PrDGAT3 may have practical applications in improving plant lipid nutrition and increasing oil production in plants.

Enhancement of sludge dewaterability by electrolysis coupled with peroxymonosulfate oxidation process: Performance, mechanisms and implications.

With the rapid increase in waste activated sludge (WAS), it is urgent to develop appropriate dewatering processes to diminish sludge volume and improve disposal efficiency. In this study, an advanced oxidation process using electrolysis coupled with peroxymonosulfate (E/PMS) was applied to improve the dewaterability of WAS. The results indicated that the sludge water content (WC) and capillary suction time (CST) dropped from 98.4 ± 0.2% and 220.1 ± 2.3 s to 70.7 ± 0.8% and 63.0 ± 1.2 s, respectively, under the following conditions: an electrolysis voltage of 20 V, an electrolysis time of 20 min, and 200 mg/g TS PMS. The increase in sludge zeta potential, surface hydrophobicity, and flowability indicated a significant improvement in sludge dewaterability. SO4•-, O•H, and O21 generated in the E/PMS process were responsible for the improvement of WAS dewaterability. These reactive oxygen species damaged extracellular polymeric substances (EPS), decreased fluorescent EPS components, and transformed the extracellular protein secondary structures by influencing the H-bond actions that maintain the α-helix. The bound water content, and apparent viscosity of WAS were found to be reduced, which was also attributed to an increase in dewatering capacity. Additionally, E/PMS treatment enhanced the degradation of organic matter in sludge and reduced the toxicity of the filtrate as well as the bioavailability of heavy metals. The cost analysis found that the E/PMS process was relatively economical and has great potential for practical application.

Corrigendum: A Tree Peony Trihelix Transcription Factor PrASIL1 Represses Seed Oil Accumulation.

[This corrects the article DOI: 10.3389/fpls.2021.796181.].

A Tree Peony Trihelix Transcription Factor PrASIL1 Represses Seed Oil Accumulation.

In many higher plants, seed oil accumulation is governed by complex multilevel regulatory networks including transcriptional regulation, which primarily affects fatty acid biosynthesis. Tree peony (Paeonia rockii), a perennial deciduous shrub endemic to China is notable for its seed oil that is abundant in unsaturated fatty acids. We discovered that a tree peony trihelix transcription factor, PrASIL1, localized in the nucleus, is expressed predominantly in developing seeds during maturation. Ectopic overexpression of PrASIL1 in Nicotiana benthamiana leaf tissue and Arabidopsis thaliana seeds significantly reduced total fatty acids and altered the fatty acid composition. These changes were in turn associated with the decreased expression of multitudinous genes involved in plastidial fatty acid synthesis and oil accumulation. Thus, we inferred that PrASIL1 is a critical transcription factor that represses oil accumulation by down-regulating numerous key genes during seed oil biosynthesis. In contrary, up-regulation of oil biosynthesis genes and a significant increase in total lipids and several major fatty acids were observed in PrASIL1-silenced tree peony leaves. Together, these results provide insights into the role of trihelix transcription factor PrASIL1 in controlling seed oil accumulation. PrASIL1 can be targeted potentially for oil enhancement in tree peony and other crops through gene manipulation.

New insights into Paeoniaceae used as medicinal plants in China.

Paeoniaceae is an abundant germplasm resource with significant medicinal values in China, the principal medicinal components of which include paeoniflorin and paeonol. These compounds are typically obtained from air-dried root samples, which the use of freeze-drying as an alternative method has not been tested. Additionally, the presence of these two compounds in various wild Paeoniaceae species has not been previously explored, nor have the differences between various plant organs been fully evaluated. Here, freeze-drying and air-drying methods were compared to assess the changes in paeoniflorin and paeonol in root samples using ultra-performance liquid chromatography-mass spectrometer. The contents of these compounds in the roots, leaves, stems, and petals were then tested in freeze-dried materials. We also quantitatively detected the paeoniflorin and paeonol contents in the roots of 14 species collected from 20 natural habitats. Results indicated that the paeoniflorin content decreased under air-drying in comparison to freeze-drying, while the opposite trend was observed for paeonol. Our findings also demonstrated that the root xylem of species in Section Moutan, particularly Paeonia ostii, contains considerable paeonol and paeoniflorin and should thus be fully utilized as a medicinal resource. Furthermore, paeonol was mainly detected in the roots, while paeoniflorin was widely distributed in different organs; the highest content was in the leaf at the budding stage, suggesting that the leaves should be developed as a new paeoniflorin resource. Paeoniflorin contents were also found to be higher at earlier development stages. Based on the standards of the Chinese Pharmacopoeia, five species of Section Moutan and six species of Section Paeonia could be used as potential traditional Chinese medicinal resources. These findings of this study enhance our understanding of these two medicinal compounds and provide a foundation for the further development and utilization of Paeoniaceae as medicinal plant resources.

Comparative transcriptome analyses reveal genes related to pigmentation in the petals of red and white Primula vulgaris cultivars.

Primula vulgaris is an important ornamental plant species with various flower color. To explore the molecular mechanism of its color formation, comparative transcriptome analyses of the petals in red and white cultivars was performed. A total of 4451 differentially expressed genes were identified and annotated into 128 metabolic pathways. Candidate genes FLS, F3'H, DFR, ANS and AOMT in the anthocyanin pathway were expressed significantly higher in the red cultivar than the white and may be responsible for the red coloration. In the red petals, a putative transcription factors bHLH (c52273.graph_c0) was up-regulated about 14-fold, while a R2R3-MYB unigene (c36140.graph_c0) was identified as a repressor involved in anthocyanin regulation and was significantly down-regulated. In addition, the anatomy analyses and pigments composition in the red and white petals were also analyzed. The papillae on the adaxial epidermis of the red petals of P. vulgaris display a triangle-shapes, in contrast with a spherical shape for the white petals. Although flavonoids were detected in both cultivars, anthocyanins could only be identified in the red cultivar. Gossypetin and peonidin/rosinin were the most abundant pigments in red petals. This study shed light on the genetic and biochemistry mechanisms underlying the flower coloration in Primula.