Lily LlHSFC2 coordinates with HSFAs to balance heat stress response and improve thermotolerance.

Heat stress transcription factors (HSFs) are core regulators of plant heat stress response. Much research has focused on class A and B HSFs, leaving those of class C relatively understudied. Here, we reported a lily (Lilium longiflorum) heat-inducible HSFC2 homology involved in thermotolerance. LlHSFC2 was located in the nucleus and cytoplasm and exhibited a repression ability by binding heat stress element. Overexpression of LlHSFC2 in Arabidopsis, tobacco (Nicotiana benthamiana), and lily, all increased the thermotolerance. Conversely, silencing of LlHSFC2 in lily reduced its thermotolerance. LlHSFC2 could interact with itself, or interact with LlHSFA1, LlHSFA2, LlHSFA3A, and LlHSFA3B of lily, AtHSFA1e and AtHSFA2 of Arabidopsis, and NbHSFA2 of tobacco. LlHSFC2 interacted with HSFAs to accelerate their transactivation ability and act as a transcriptional coactivator. Notably, compared with the separate LlHSFA3A overexpression, co-overexpression of LlHSFC2/LlHSFA3A further enhanced thermotolerance of transgenic plants. In addition, after suffering HS, the homologous interaction of LlHSFC2 was repressed, but its heterologous interaction with the heat-inducible HSFAs was promoted, enabling it to exert its co-activation effect for thermotolerance establishment and maintenance. Taken together, we identified that LlHSFC2 plays an active role in the general balance and maintenance of heat stress response by cooperating with HSFAs, and provided an important candidate for the enhanced thermotolerance breeding of crops and horticulture plants.

An efficient CRISPR/Cas9 platform for targeted genome editing in rose (Rosa hybrida).

The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-related nuclease 9 (Cas9) system enables precise, simple editing of genes in many animals and plants. However, this system has not been applied to rose (Rosa hybrida) due to the genomic complexity and lack of an efficient transformation technology for this plant. Here, we established a platform for screening single-guide RNAs (sgRNAs) with high editing efficiency for CRISPR/Cas9-mediated gene editing in rose using suspension cells. We used the Arabidopsis thaliana U6-29 promoter, which showed high activity for driving sgRNA expression, to modify the CRISPR/Cas9 system. We used our highly efficient optimized CRISPR/Cas9 system to successfully edit RhEIN2, encoding an indispensable component of the ethylene signaling pathway, resulting in ethylene insensitivity in rose. Our optimized CRISPR/Cas9 system provides a powerful toolbox for functional genomics, molecular breeding, and synthetic biology in rose.

The Heat Stress Transcription Factor LlHsfA4 Enhanced Basic Thermotolerance through Regulating ROS Metabolism in Lilies (Lilium Longiflorum).

Heat stress severely affects the annual agricultural production. Heat stress transcription factors (HSFs) represent a critical regulatory juncture in the heat stress response (HSR) of plants. The HsfA1-dependent pathway has been explored well, but the regulatory mechanism of the HsfA1-independent pathway is still under-investigated. In the present research, HsfA4, an important gene of the HsfA1-independent pathway, was isolated from lilies (Lilium longiflorum) using the RACE method, which encodes 435 amino acids. LlHsfA4 contains a typical domain of HSFs and belongs to the HSF A4 family, according to homology comparisons and phylogenetic analysis. LlHsfA4 was mainly expressed in leaves and was induced by heat stress and H2O2 using qRT-PCR and GUS staining in transgenic Arabidopsis. LlHsfA4 had transactivation activity and was located in the nucleus and cytoplasm through a yeast one hybrid system and through transient expression in lily protoplasts. Over expressing LlHsfA4 in Arabidopsis enhanced its basic thermotolerance, but acquired thermotolerance was not achieved. Further research found that heat stress could increase H2O2 content in lily leaves and reduced H2O2 accumulation in transgenic plants, which was consistent with the up-regulation of HSR downstream genes such as Heat stress proteins (HSPs), Galactinol synthase1 (GolS1), WRKY DNA binding protein 30 (WRKY30), Zinc finger of Arabidopsis thaliana 6 (ZAT6) and the ROS-scavenging enzyme Ascorbate peroxidase 2 (APX2). In conclusion, these results indicate that LlHsfA4 plays important roles in heat stress response through regulating the ROS metabolism in lilies.

MicroRNA-135b-5p Downregulation Causes Antidepressant Effects by Regulating SIRT1 Expression.

Depression is a serious and potentially life-threatening mental illness. Recently, the role of sirtuin 1 (SIRT1) in chronic unpredictable mild stress (CUMS) management has been examined. The present study explored and clarified whether microRNA (miR)-135b-5p could play a role in depression by regulating the expression of SIRT1. SIRT1 was identified as the target gene of miR-135b-5p using TargetScan and the dual luciferase reporter assay. In addition, the expression levels of SIRT1 were significantly reduced in mouse peripheral blood and hippocampal tissue samples, while the expression of miR-135b-5p exhibited the opposite effects. Subsequently, the effects of miR-135b-5p inhibition were investigated in mice with depression. The results indicated that the miR-135b-5p inhibitor significantly increased the weight loss induced by CUMS compared with the model group, while reducing the expression levels of miR-135b-5p and further alleviating the depression-like behavior induced by CUMS. Concomitantly, the results indicated that the miR-135b-5p inhibitor inhibited CUMS-induced hippocampal cell apoptosis and significantly reduced the expression levels of cleaved caspase-3 and the ratio of cleaved caspase-3/caspase-3. Moreover, the miR-135b-5p inhibitor significantly reduced the CUMS-induced increase of the inflammatory factors IL-1ß, IL-6 and TNF-α in the hippocampal mouse samples, while significantly increasing the expression levels of SIRT1. Finally, the results demonstrated that all the effects of the miR-135b-5p inhibitor on CUMS-induced mice were significantly reversed by SIRT1 silencing. In conclusion, the present study indicated that the miR-135b-5p/SIRT1 pathway was a key mediator of antidepressant effects induced in depressed mice. Therefore, it could be considered a potential therapeutic target for the treatment of CUMS-induced depression.

Intramolecular ß-Alkenylation of Cyclohexanones via Pd-Catalyzed Desaturation-Mediated C(sp3)-H/Alkyne Coupling.

Site-selective C-C bond formation through the direct coupling of C(sp3)-H bonds with unsaturated hydrocarbons represents an atom-economical and redox-neutral way to functionalize chemically inert positions, such as those ß to a carbonyl group. While most existing ß-functionalization methods utilize a directing group (DG) strategy, here we report a Pd-catalyzed intramolecular ß-alkenylation of ketones using alkynes as the coupling partner without the aid of DGs. Mediated by a ketone desaturation process, the reaction is redox-neutral and avoids using strong acids or bases. The resulting cis-5,6-fused bicycles can be diversely derivatized with excellent selectivity. Mechanistic studies imply an unusual "hydride-transfer" chain-like pathway, which involves the cyclometalation of an enyne intermediate and protonation of the resulting Pd enolate followed by an intermolecular hydride transfer through the desaturation of another substrate.

Alternative Splicing Provides a Mechanism to Regulate LlHSFA3 Function in Response to Heat Stress in Lily.

Heat stress transcription factors (HSFs) are central regulators of plant responses to heat stress. Their heat-induced transcriptional regulation has been extensively studied; however, their posttranscriptional and posttranslational regulation is poorly understood. In a previous study, we established that there were at least two HSFA3 homologs, LlHSFA3A and LlHSFA3B, in lily (Lilium spp.) and that these genes played distinct roles in thermotolerance. Here, we demonstrate that LlHSFA3B is alternatively spliced under heat stress to produce the heat-inducible splice variant LlHSFA3B-III We further show that LlHSFA3B-III protein localizes in the cytoplasm and nucleus, has no transcriptional activity, and specifically disturbs the protein interactions of intact HSFA3 orthologs LlHSFA3A-I and LlHSFA3B-I. Heterologous expression of LlHSFA3B-III in Arabidopsis (Arabidopsis thaliana) and Nicotiana benthamiana increased plant tolerance of salt and prolonged heat at 40°C, yet reduced plant tolerance of acute heat shock at 45°C. Conversely, heterologous expression of LlHSFA3A-I caused opposing phenotypes, which were substantially ameliorated by coexpression of LlHSFA3B-III LlHSFA3B-III interacted with LlHSFA3A-I to limit its transactivation function and temper the function of LlHSFA3A-I, thus reducing the adverse effects of excessive LlHSFA3A-I accumulation. Based on these observations, we propose a regulatory mechanism of HSFs involving heat-inducible alternative splicing and protein interaction, which might be used in strategies to promote thermotolerance and attenuate the heat stress response in crop plants.

Molecular Evidences for the Interactions of Auxin, Gibberellin, and Cytokinin in Bent Peduncle Phenomenon in Rose (Rosa sp.).

In roses (Rosa sp.), peduncle morphology is an important ornamental feature. The common physiological abnormality known as the bent peduncle phenomenon (BPP) seriously decreases the quality of rose flowers and thus the commercial value. Because the molecular mechanisms underlying this condition are poorly understood, we analysed the transcriptional profiles and cellular structures of bent rose peduncles. Numerous differentially expressed genes involved in the auxin, cytokinin, and gibberellin signaling pathways were shown to be associated with bent peduncle. Paraffin sections showed that the cell number on the upper sides of bent peduncles was increased, while the cells on the lower sides were larger than those in normal peduncles. We also investigated the large, deformed sepals that usually accompany BPP and found increased expression level of some auxin-responsive genes and decreased expression level of genes that are involved in cytokinin and gibberellin synthesis in these sepals. Furthermore, removal of the deformed sepals partially relieved BPP. In summary, our findings suggest that auxin, cytokinin, and gibberellin all influence the development of BPP by regulating cell division and expansion. To effectively reduce BPP in roses, more efforts need to be devoted to the molecular regulation of gibberellins and cytokinins in addition to that of auxin.

Kinetic Resolution via Rh-Catalyzed C-C Activation of Cyclobutanones at Room Temperature.

Herein we describe the development of a highly selective kinetic resolution of cyclobutanones via a Rh-catalyzed "cut-and-sew" reaction with selectivity factor up to 785. This reaction takes place at room temperature with excellent efficiency. Various trans-5,6-fused bicycles and C2-substituted cyclobutanones were obtained with excellent ee's that can be further used as chiral building blocks. DFT calculations reveal the crucial roles of the DTBM-segphos ligand in stabilizing the rate- and enantioselectivity-determining C-C oxidative addition transition state via favorable ligand-substrate dispersion interactions.

Direct ß-Alkylation of Ketones and Aldehydes via Pd-Catalyzed Redox Cascade.

We report a direct ß-alkylation of ketones and aldehydes with simple alkyl bromides through a Pd-catalyzed redox-cascade strategy. The use of a Cu cocatalyst is important for improved efficiency. The reaction is redox-neutral, without the need for strong acids or bases. Both cyclic and acyclic ketones, as well as α-branched aldehydes, are suitable substrates for coupling with secondary and tertiary alkyl bromides. Concise formal synthesis of Zanapezil is achieved using this ß-alkylation method.

Petal senescence: a hormone view.

Flowers are highly complex organs that have evolved to enhance the reproductive success of angiosperms. As a key component of flowers, petals play a vital role in attracting pollinators and ensuring successful pollination. Having fulfilled this function, petals senesce through a process that involves many physiological and biochemical changes that also occur during leaf senescence. However, petal senescence is distinct, due to the abundance of secondary metabolites in petals and the fact that petal senescence is irreversible. Various phytohormones are involved in regulating petal senescence, and are thought to act both synergistically and antagonistically. In this regard, there appears to be developmental point during which such regulatory signals are sensed and senescence is initiated. Here, we review current understanding of petal senescence, and discuss associated regulatory mechanisms involving hormone interactions and epigenetic regulation.

Overexpression of lily HsfA3s in Arabidopsis confers increased thermotolerance and salt sensitivity via alterations in proline catabolism.

Although HsfA3 (heat-stress transcription factor A3) is well characterized in heat stress, its roles in other abiotic stresses are less clear. In this study, we isolated two homologous HsfA3 genes, LlHsfA3A and LlHsfA3B, from lily (Lilium longiflorum). Both genes were induced by heat stress, but not by salt stress. Overexpressing LlHsfA3A in Arabidopsis enhanced its basal and acquired thermotolerance, while overexpressing LlHsfA3B just enhanced its acquired thermotolerance. In both cases, overexpressing plants showed hypersensitivity to salt stress, and a lack of sucrose exacerbated this salt sensitivity. Using a transient assay, the opposite effects were observed in lily. Further analysis revealed that either LlHsfA3A or LlHsfA3B overexpression altered normal proline accumulation. During heat treatments, proline increased in wild-type Arabidopsis plants, but no such increase was detected in transgenic plants that showed better basal or acquired thermotolerance. Under salt stress, proline accumulation was decreased in Arabidopsis and lily with the overexpression of LlHsfA3A or LlHsfA3B. Proline catabolism was activated by overexpression, and both LlHsfA3A and LlHsfA3B affected proline oxidation via regulation of AtbZIP11, AtbZIP44, and AtbZIP53 to activate AtproDH1 and AtproDH2 in transgenic Arabidopsis. Taken together, our results suggested that overexpression of LlHsfA3A or LlHsfA3B caused opposite effects on heat and salt tolerance, which may implicate proline catabolism.

A Hydrazone-Based exo-Directing-Group Strategy for ߆C-H Oxidation of Aliphatic Amines.

Described is a new hydrazone-based exo-directing group (DG) strategy developed for the functionalization of unactivated primary ß C-H bonds of aliphatic amines. Conveniently synthesized from protected primary amines, the hydrazone DGs are shown to site-selectively promote the ß-acetoxylation and tosyloxylation via five-membered exo-palladacycles. Amines with a wide scope of skeletons and functional groups are tolerated. Moreover, the hydrazone DG can be readily removed, and a one-pot C-H acetoxylation/DG removal protocol was also discovered.

Reaction of Diazo Compounds with Difluorocarbene: An Efficient Approach towards 1,1-Difluoroolefins.

A transition-metal-free difluoromethylenation of diazo compounds that proceeds under mild conditions has been developed and is based on the use of TMSCF2 Br as the difluoromethylene source and tetrabutylammonium bromide (TBAB) as the promoter. The chemoselective formal carbene dimerization reaction is achieved owing to the electronic properties and the relative stability of the difluorocarbene intermediate.

Catalytic C(sp(3) )-H Arylation of Free Primary Amines with an exo Directing Group Generated In†Situ.

Herein, we report the palladium-catalyzed direct arylation of unactivated aliphatic C-H bonds in free primary amines. This method takes advantage of an exo-imine-type directing group (DG) that can be generated and removed in situ. A range of unprotected aliphatic amines are suitable substrates, undergoing site-selective arylation at the γ-position. Methyl as well as cyclic and acyclic methylene groups can be activated. Furthermore, when aniline-derived substrates were used, preliminary success with δ-C-H arylation was achieved. The feasibility of using the DG component in a catalytic fashion was also demonstrated.

Palladium-catalyzed C-H functionalization of acyldiazomethane and tandem cross-coupling reactions.

Palladium-catalyzed C-H functionalization of acyldiazomethanes with aryl iodides has been developed. This reaction is featured by the retention of the diazo functionality in the transformation, thus constituting a novel method for the introduction of diazo functionality to organic molecules. Consistent with the experimental results, the density functional theory (DFT) calculation indicates that the formation of Pd-carbene species in the catalytic cycle through dinitrogen extrusion from the palladium ethyl diazoacetate (Pd-EDA) complex is less favorable. The reaction instead proceeds through Ag2CO3 assisted deprotonation and subsequently reductive elimination to afford the products with diazo functionality remained. This C-H functionalization transformation can be further combined with the recently evolved palladium-catalyzed cross-coupling reaction of diazo compounds with aryl iodides to develop a tandem coupling process for the synthesis of α,α-diaryl esters. DFT calculation supports the involvement of Pd-carbene as reactive intermediate in the catalytic cycle, which goes through facile carbene migratory insertion with a low energy barrier (3.8 kcal/mol).

Construction of All-Carbon Quaternary Centers through Cu-Catalyzed Sequential Carbene Migratory Insertion and Nucleophilic Substitution/Michael Addition.

A Cu-catalyzed three-component cross-coupling reaction of terminal alkyne, α-diazo ester, and alkyl halide has been developed. This transformation involves sequent migratory insertion of copper-carbene and nucleophilic substitution, in which a C(sp)-C(sp(3)) bond and a C(sp(3))-C(sp(3)) bond are formed successively on a carbenic center. Michael addition acceptors can also be employed instead of alkyl halides that enable Michael addition to be an alternative way to build C(sp(3))-C(sp(3)) bond. This transformation represents a highly efficient method for the construction of all-carbon quaternary centers.

Synthesis of Terminal Allenes through Copper-Mediated Cross-Coupling of Ethyne with N-Tosylhydrazones or α-Diazoesters.

Ethyne is employed as coupling partner in copper-mediated cross-coupling reactions with N-tosylhydrazones and α-diazoacetate, leading to the development of a new synthetic method for terminal allenes. With this novel coupling method, the terminal allenes were obtained in good yields and with excellent functional group tolerance. Copper carbene migratory insertion is proposed as the key step in these transformations.

Synthesis of aryldiazoacetates through palladium(0)-catalyzed deacylative cross-coupling of aryl iodides with acyldiazoacetates.

Palladium(0)-catalyzed deacylative cross-coupling of aryl iodides and acyldiazocarbonyl compounds can be achieved at room temperature under mild reaction conditions. The coupling reaction represents a highly efficient and general method for the synthesis of aryldiazocarbonyl compounds, which have found wide and increasing applications as precursors for generating donor/acceptor-substituted metallocarbenes.

SO3 removal by submicron absorbents synthesized via inhibition method: The product layer grows like parallel peaks.

Injecting calcium hydroxide powder into the flue gas is an effective strategy for SO3 removal. However, commercial calcium hydroxide has several disadvantages, including large particle size, low efficiency, and unsuitability for excessive grinding. In this work, sub-micron calcium hydroxide was synthesized by an inhibition method and its performance for SO3 removal from flue gas was investigated on a pilot-scale platform (120 Nm3/h). When the concentration of sodium alginate solution was 100 mg/L, the average particle size of calcium hydroxide decreased from 13.66 µm to 0.84 µm, which improved the SO3 removal (92.1 %) and conversion of the absorbent. The results of the fixed-bed experiments indicate that the absorption kinetics of the reaction is consistent with the Bangham model. In addition, density functional theory verifies that calcium hydroxide captures SO3 by chemisorption. The AFM image shows that the calcium sulfate whiskers produced during the reaction grow like parallel peaks on the adsorbent surface. The calculations suggest that the driving force for SO3 adsorption originates from Ca-p orbital (Ca(OH)2) and O-s orbital (SO3) hybridization. This study complements the island growth mechanism for gas-solid two-phase reactions and provides an effective method for removing SO3 from flue gas in coal-fired power plants. In addition, it will provide an important reference for the development of submicron adsorbents.

Phase Change Study of a New Two-Phase Absorbent Based on DAP.

In order to overcome the drawbacks of conventional absorbents, which exhibit slow absorption rates and low absorption loads, this study suggests enhancing the absorbent system for CO2 absorption by incorporating a nonaqueous solvent into 1,3-propanediamine (DAP) and tetramethylethylenediamine (TMEDA), resulting in a two-phase system. The mechanism of solvent absorption of CO2 was investigated using nuclear magnetic resonance (NMR) carbon spectroscopy. By comparing the absorption load, fraction ratio, and viscosity of different absorbents after absorbing carbon dioxide, the two-phase absorbents with good performance were selected. The poor water absorbent consisting of the DAP/TMEDA system exhibited an absorption load of 3.8 mol/kg, surpassing that of the conventional 30% ethanolamine solution. A nonaqueous solvent is added to the system to replace some of the water to reduce the fraction. After adding different nonaqueous solvents, the phase separation system was screened after 2 h of CO2 absorption. The system with good performance was tested for the absorption of the solution under different amine concentration and water concentration tests. It is found that the absorption load of the DAP/TMEDA/diglyme system is 3.2 mol/kg, but the fraction can be reduced to 38%. The significant reduction in rich phase volume is beneficial for reducing the size and cost of regeneration tower. According to NMR detection and quantum chemical calculations, it was found that DAP/TMEDA absorbs carbon dioxide to form carbamate. DAP acts as the main absorbent, while TMEDA and nonaqueous solvents do not participate in the absorption reaction. Nonaqueous solvents were found to accelerate the solution phase separation due to the salt precipitation reaction.