The transcription factor SbHY5 mediates light to promote aluminum tolerance by activating SbMATE and SbSTOP1s expression.

Aluminum (Al) toxicity is a major factor limiting crop yields in acid soils. Sweet sorghum (Sorghum bicolor L.) is a high-efficient energy crop widely grown in tropical and subtropical regions of the world, where acid soil is common and Al toxicity is widespread. Here, we characterized a transcription factor SbHY5 in sweet sorghum, which mediated light to promote plant Al stress adaptation. The expression of SbHY5 was induced by Al stress and increasing light intensity. The overexpression of SbHY5 improved Al tolerance in transgenic plants, which was associated with increased citrate secretion and reduced Al content in roots. Meanwhile, SbHY5 was found to localize to the nucleus and displayed transcriptional activity. SbHY5 directly activated the expression of SbMATE, indicating that a HY5-MATE-dependent citrate secretion pathway is involved in Al tolerance in plants. SbSTOP1 was reported as a key transcription factor, regulating several Al tolerance genes. Here, inspiringly, we found that SbHY5 directly promoted the transcription of SbSTOP1, implying the existence of HY5-STOP1-Al tolerance genes-mediated regulatory pathways. Besides, SbHY5 positively regulated its own transcription. Our findings revealed a novel regulatory network in which a light signaling factor, SbHY5, confers Al tolerance in plants by modulating the expression of Al stress response genes.

Two Sweet Sorghum (Sorghum bicolor L.) WRKY Transcription Factors Promote Aluminum Tolerance via the Reduction in Callose Deposition.

Aluminum (Al) toxicity is a primary limiting factor for crop production in acidic soils. The WRKY transcription factors play important roles in regulating plant growth and stress resistance. In this study, we identified and characterized two WRKY transcription factors, SbWRKY22 and SbWRKY65, in sweet sorghum (Sorghum bicolor L.). Al induced the transcription of SbWRKY22 and SbWRKY65 in the root apices of sweet sorghum. These two WRKY proteins were localized in the nucleus and exhibited transcriptional activity. SbWRKY22 showed the significant transcriptional regulation of SbMATE, SbGlu1, SbSTAR1, SbSTAR2a, and SbSTAR2b, which are major known Al tolerance genes in sorghum. Interestingly, SbWRKY65 had almost no effect on the aforementioned genes, but it significantly regulated the transcription of SbWRKY22. Therefore, it is speculated that SbWRKY65 might indirectly regulate Al-tolerance genes mediated by SbWRKY22. The heterologous expression of SbWRKY22 and SbWRKY65 greatly improved the Al tolerance of transgenic plants. The enhanced Al tolerance phenotype of transgenic plants is associated with reduced callose deposition in their roots. These findings suggest the existence of SbWRKY22- and SbWRKY65-mediated Al tolerance regulation pathways in sweet sorghum. This study extends our understanding of the complex regulatory mechanisms of WRKY transcription factors in response to Al toxicity.

Mechanism of action of non-coding RNAs and traditional Chinese medicine in myocardial fibrosis: Focus on the TGF-ß/Smad signaling pathway.

Cardiac fibrosis is a serious public health problem worldwide that is closely linked to progression of many cardiovascular diseases (CVDs) and adversely affects both the disease process and clinical prognosis. Numerous studies have shown that the TGF-ß/Smad signaling pathway plays a key role in the progression of cardiac fibrosis. Therefore, targeted inhibition of the TGF-ß/Smad signaling pathway may be a therapeutic measure for cardiac fibrosis. Currently, as the investigation on non-coding RNAs (ncRNAs) move forward, a variety of ncRNAs targeting TGF-ß and its downstream Smad proteins have attracted high attention. Besides, Traditional Chinese Medicine (TCM) has been widely used in treating the cardiac fibrosis. As more and more molecular mechanisms of natural products, herbal formulas, and proprietary Chinese medicines are revealed, TCM has been proven to act on cardiac fibrosis by modulating multiple targets and signaling pathways, especially the TGF-ß/Smad. Therefore, this work summarizes the roles of TGF-ß/Smad classical and non-classical signaling pathways in the cardiac fibrosis, and discusses the recent research advances in ncRNAs targeting the TGF-ß/Smad signaling pathway and TCM against cardiac fibrosis. It is hoped, in this way, to give new insights into the prevention and treatment of cardiac fibrosis.

RNA-binding protein MAC5A interacts with the 26S proteasome to regulate DNA damage response in Arabidopsis.

DNA damage response (DDR) in eukaryotes is essential for the maintenance of genome integrity in challenging environments. The regulatory mechanisms of DDR have been well-established in yeast and humans. However, increasing evidence supports the idea that plants seem to employ different signaling pathways that remain largely unknown. Here, we report the role of MODIFIER OF SNC1, 4-ASSOCIATED COMPLEX SUBUNIT 5A (MAC5A) in DDR in Arabidopsis (Arabidopsis thaliana). Lack of MAC5A in mac5a mutants causes hypersensitive phenotypes to methyl methanesulfonate (MMS), a DNA damage inducer. Consistent with this observation, MAC5A can regulate alternative splicing of DDR genes to maintain the proper response to genotoxic stress. Interestingly, MAC5A interacts with the 26S proteasome (26SP) and is required for its proteasome activity. MAC core subunits are also involved in MMS-induced DDR. Moreover, we find that MAC5A, the MAC core subunits, and 26SP may act collaboratively to mediate high-boron-induced growth repression through DDR. Collectively, our findings uncover the crucial role of MAC in MMS-induced DDR in orchestrating growth and stress adaptation in plants.

Characterization of GmMATE13 in its contribution of citrate efflux and aluminum resistance in soybeans.

Citrate exudation mediated by a citrate transporter of the MATE protein family is critical for resisting aluminum (Al) toxicity in soybeans. However, the expression patterns of citrate transporter genes differ under Al stress. Thus, exploring the responsive pattern of GmMATEs in response to Al stress is of great importance to understand the Al resistance mechanism in soybeans. In the present study, the phylogenetic analysis, transcriptionally expressed pattern, and function of GmMATE13 were investigated. The results show that soybean GmMATE13 is highly homologous to known citrate transporter proteins from other plants. Under Al exposure, the transcript abundance of GmMATE13 was increased during a 24 h Al treatment period. The expression of GmMATE13 is specifically induced by Al exposure, but not by the status of Fe, Cu, Cd, or La. Moreover, it was also highly increased when soybean seedlings were grown on acidic soil with a high Al content. Subcellular localization showed that GmMATE13 was localized on the plasma membrane when it was transiently expressed in Arabidopsis protoplasts. Investigation of tissue localization of GmMATE13 expression by investigating GUS activity staining under control of the GmMATE13 promoter showed that it was mainly expressed in the central cylinder in the root tips of the soybean under Al-free conditions, yet extended to cortical and epidermis cells under Al stress. Finally, overexpressing GmMATE13 in soybean hairy roots enhanced Al resistance by increasing citrate efflux. Collectively, we conclude that GmMATE13 is a promising candidate to improve the resistance of soybean to Al toxicity in acidic soil.

Hybrid non-sequential modeling of an image mapping spectrometer.

An image mapping spectrometer (IMS) is a kind of snapshot imaging spectrometer characterized by containing several array components including the image mapper, prism array, and reimaging lens array. We propose a hybrid non-sequential modeling method of IMS and present the complete optical model of the system built in Zemax. This method utilizes the spatial periodicity of the array components and requires only a small number of input parameters. Moreover, we design a collimating lens of a large relative aperture, sufficient working distance, and low aberration to meet the requirements of an IMS with good optical performance and compact volume. The designed lens is quantitatively evaluated in the entire IMS model, and the results demonstrate that the lens has excellent optical performance. The evaluation on the collimating lens also demonstrates the capability of the proposed modeling method in the design and optimization of systems such as the IMS that contain multiple array components. The designed collimating lens is manufactured and assembled in the experimental setup of the IMS. The proposed modeling method is verified by experimental results.

The Double-Edged Sword Effect of Paradoxical Leadership to Organizational Citizenship Behavior.

Purpose: Drawing on social exchange theory and attribution theory, this study aims to explore the influencing mechanism of paradoxical leadership on organizational citizenship behavior. Participants and Methods: According to the research purpose, this study selects enterprises in the manufacturing, financial and high-tech industries in Shandong Province as the research objects, and collects data on the leaders and employees of the human resources departments and marketing departments in the enterprises. Data were collected from 77 leaders and 473 employees in China by a two-wave questionnaire survey. Hierarchical regression analysis and structural equation model approach were employed to test hypotheses. Results: This study found that perceived insider status and psychological entitlement play mediating roles about paradoxical leadership and organizational citizenship behavior; Collectivism moderates the relationship between paradoxical leadership and perceived insider status, and moderates the positive mediating role played by perceived insider status in the relationship of paradoxical leadership and organizational citizenship behavior; Leader-member exchange differentiation moderates the relationship about paradoxical leadership and psychological entitlement, and moderates negative mediating role played by psychological entitlement in the relationship of paradoxical leadership's and organizational citizenship behavior. Conclusion: The findings of this study offer guidance for managers to better undermine the negative effects of paradoxical leadership, and improve organizational citizenship behavior. Innovations: First, this study extends the literature on paradoxical leadership by verifying the double-edged sword effect of paradoxical leadership to organizational citizenship behavior. Second, this study enriches one's understanding of the "black box" underlying the link between paradoxical leadership and its consequences by demonstrating the mediating roles of perceived insider status and psychological entitlement. Third, by verifying the moderating roles of collectivism and leader-member exchange differentiation, this study provides insights into the boundary conditions of the impact of paradoxical leadership.

Kinetic Model and Numerical Simulation of Microbial Growth, Migration, and Oil Displacement in Reservoir Porous Media.

Microbial enhanced oil recovery (MEOR) is a potential tertiary oil recovery method. However, past research has failed to describe microbial growth and metabolism reasonably, especially quantification of reaction equations and operating parameters is still not clear. The present study investigated the ability of bacteria extracted from Ansai Oilfield for MEOR. Through core flooding experiments, bacteria-treated experiments produced approximately 6.28-9.81% higher oil recovery than control experiments. Then, the microbial reaction kinetic model was established based on laboratory experimental data and mass conservation. Furthermore, the proposed model was validated by matching core flooding experiment results. Lastly, the effects of different injection parameters on bacteria growth, bacteria migration, metabolite migration, residual oil distribution, and oil recovery were studied by establishing a field-scale model. The results indicate that the injected bacteria concentration and nutrient concentration have a great influence on bacteria growth in a reservoir and the low nutrient concentration seriously restricts bacteria growth. Compared with the injected bacteria concentration, nutrient concentration has a decisive effect on bacteria and metabolite migration. The injected bacteria concentration has little effect on oil recovery, while nutrient concentration and slug volume have a significant effect on oil recovery.

GWAS on multiple traits identifies mitochondrial ACONITASE3 as important for acclimation to submergence stress.

Flooding causes severe crop losses in many parts of the world. Genetic variation in flooding tolerance exists in many species; however, there are few examples for the identification of tolerance genes and their underlying function. We conducted a genome-wide association study (GWAS) in 387 Arabidopsis (Arabidopsis thaliana) accessions. Plants were subjected to prolonged submergence followed by desubmergence, and seven traits (score, water content, Fv/Fm, and concentrations of nitrate, chlorophyll, protein, and starch) were quantified to characterize their acclimation responses. These traits showed substantial variation across the range of accessions. A total of 35 highly significant single-nucleotide polymorphisms (SNPs) were identified across the 20 GWA datasets, pointing to 22 candidate genes, with functions in TCA cycle, DNA modification, and cell division. Detailed functional characterization of one candidate gene, ACONITASE3 (ACO3), was performed. Chromatin immunoprecipitation followed by sequencing showed that a single nucleotide polymorphism in the ACO3 promoter co-located with the binding site of the master regulator of retrograde signaling ANAC017, while subcellular localization of an ACO3-YFP fusion protein confirmed a mitochondrial localization during submergence. Analysis of mutant and overexpression lines determined changes in trait parameters that correlated with altered submergence tolerance and were consistent with the GWAS results. Subsequent RNA-seq experiments suggested that impairing ACO3 function increases the sensitivity to submergence by altering ethylene signaling, whereas ACO3 overexpression leads to tolerance by metabolic priming. These results indicate that ACO3 impacts submergence tolerance through integration of carbon and nitrogen metabolism via the mitochondrial TCA cycle and impacts stress signaling during acclimation to stress.

Disturbance Observer-Based Feedback Linearization Control for a Quadruple-Tank Liquid Level System.

A novel input/output feedback linearization control method by utilizing nonlinear disturbance observer (NDOB) is proposed for a quadruple-tank liquid level (QTLL) system in this paper. Firstly, the mathematical model of QTLL system is established by using Bernoulli's law and mass conservation. Secondly, in view of the nonlinear and coupling characteristics of the QTLL system, a input/output feedback linearization controller is designed. Then, a NDOB is proposed to estimate disturbances and applied to compensation control. Finally, simulation and experimental results show that the proposed strategy has better control performances than PID control and the disturbance observer-based sliding mode control (DOBSMC).

Ectopic expression of IMA small peptide genes confers tolerance to cadmium stress in Arabidopsis through activating the iron deficiency response.

Increasing cadmium (Cd) pollution severely affects plant growth and development, posing risks to human health via food chains. The Cd toxicity could be mitigated by improving Fe nutrient in plants. IMA1 and IMA3, two novel small peptides functionally epistatic to the key transcription factor bHLH39 but independent of bHLH104, were recently identified as the newest additions to the Fe regulatory cascade, but their roles in Cd uptake and toxicity remain not addressed. Here, the functions of two IMAs and two transcription factors related to Cd tolerance were verified. Overexpression of either bHLH39 or bHLH104 in Arabidopsis showed weak roles in Cd tolerance, but overexpression of IMAs, which activates the Fe-deficient response, significantly enhanced Cd tolerance, showing greater root elongation, biomass and chlorophyll contents. The Cd contents did not show significant difference among the overexpression lines. Further investigations revealed that the tolerance of transgenic plants to Cd mainly depended on higher Fe accumulation, which decreased the MDA contents and enhanced root elongation under Cd exposure, finally contributing to attenuating Cd toxicity. Taken together, the results suggest that increasing Fe accumulation is promising for improving plant tolerance to Cd toxicity and that IMAs are potential candidates for solving Cd toxicity problem.

Research on the Influence of Paradoxical Leadership on Compulsory Organizational Citizenship Behavior.

PURPOSE: According to attribution theory, the purpose of this paper is to examine the relationship between paradoxical leadership and employees' compulsory organizational citizenship behavior, research the mediating and moderating effects of work pressure perception and leadership member exchange differentiation. PARTICIPANTS AND METHODS: The data collection work was carried out with 329 employees as the research object, and empirical tests were carried out using confirmatory factor analysis and hierarchical regression analysis methods. RESULTS: The results of the empirical test show that: paradoxical leadership has a significant positive effect on employees' compulsory organizational citizenship behavior; work pressure perception plays a mediating role between paradoxical leadership and employee's compulsory organizational citizenship behavior; leadership member exchange differentiation plays a moderating role between paradoxical leadership and work pressure perception. Paradoxical leadership will lead employees to adopt compulsory organizational citizenship behavior. Moreover, organizations should reduce employees' perception of work pressure and leadership member exchange differentiation. CONCLUSION: The results of the study provide positive suggestions for reducing the compulsory organizational citizenship behavior of employees by focusing on the behavior of paradoxical leadership, thereby promoting the improvement of corporate performance. INNOVATIONS: 1) The research on the influence of paradoxical leadership on compulsory organizational citizenship behavior reveals the "dark side" of the influence of paradoxical leadership on employee behavior. 2) By introducing work pressure perception, this paper reveals the mechanism of action between paradoxical leadership and compulsory organizational citizenship behavior, which provides a new research perspective for understanding the formation mechanism of employees adopting compulsory organizational citizenship behavior. 3) This paper confirms that leadership member exchange differentiation can positively moderate the relationship between paradoxical leadership and work pressure perception.

Mechanism and Selectivity of Cyclopropanation of 3-Alkenyl-oxindoles with Sulfoxonium Ylides Catalyzed by a Chiral N,N'-Dioxide-Mg(II) Complex.

The mechanism and stereoselectivity of an asymmetric cyclopropanation reaction between 3-alkenyl-oxindole and sulfoxonium ylide catalyzed by a chiral N,N'-dioxide-Mg(II) complex were explored using the B3LYP-D3(BJ) functional and the def2-TZVP basis set. The noncatalytic reaction occurred via a stepwise mechanism, with activation barriers of 21.6-23.5 kcal mol-1. The C2-Cα bond formed followed by the carbanion SN2 substitution, constructing a three-membered ring in spiro-cyclopropyl oxindoles, accompanied by the release of dimethylsulfoxide. The electron-withdrawing N-protecting t-butyloxy carbonyl (Boc) and acetyl (Ac) groups in isatin enhanced the local electrophilicity of the C2 atom and the repulsion between the two COPh groups in the reactants, contributing to high reactivity as well as good diastereoselectivity results. The N-Boc-3-phenacylideneoxindole coordinated to the chiral ligand (L-PiPr2) in a bidentate fashion, forming a hexacoordinate-Mg(II) complex as the reactive species. The origin of enantioselectivity was from the shielding effect of 2,6-diisopropylphenyl groups in the ligand toward the si-face of oxindole. The repulsion between the SO(CH3)2 and COPh groups in 3-alkenyl-oxindole and the neighboring ortho-iPr group in the ligand directed the re-face of ylide to attack the re-face of oxindole preferably, contributing to the high diastereoselectivity of the product. A metal-ion-ligand matching relationship was important for a good asymmetric induction effect of the chiral N,N'-dioxide-metal catalyst. A large chiral cavity in the Zn(II) catalyst weakened the shielding effect of 2,6-diisopropylphenyl groups in the ligand toward the prochiral face of oxindole, leading to inferior enantioselectivity observed in the experiment.

Identification of testicular Foxq1 as a critical modulator of lactate metabolism in mouse Sertoli cells.

Postmeiotic germ cells require the lactate produced by the adjacent Sertoli cells (SCs) as their sole energy fuels. Lactate production in SCs is elaborately regulated by monitoring the transcription of the lactate dehydrogenase A (Ldha) gene. However, the transcription factors that are responsible for the control of Ldha transcription in SCs remain ill defined. Herein, the expression of forkhead box Q1 (FOXQ1), a central modulator of glucose metabolism in liver, was demonstrated in mouse testis throughout postnatal development, with maximum levels in adult specimens. At this age, FOXQ1 was immunolocalized in the nuclei of the functionally mature SCs. Testicular levels of FOXQ1 were overtly modulated by germ cells (GCs)-derived IL-1α, in a dose- and time-dependent manner. To further clarify the biological functions of FOXQ1, we disrupted the mouse Foxq1 gene using a Cas9/RNA-mediated gene targeting strategy. Foxq1-/- males were subfertile and showed oligoasthenozoospermia due to lactate deficiency. Moreover, we provided the molecular evidence that FOXQ1 may regulate lactate production by directly targeting the transactivation of the Ldha gene in SCs. From a functional standpoint, overexpression of the exogenous Ldha ameliorated Foxq1 deficiency-impaired lactate synthesis in the SCsFoxq1-/- cells. Thus, these findings collectively underscore a reproductive facet of this recently characterized transcription factor, which may operate as a novel transcriptional integrator linking energy homeostasis and nursery function in SCs.

Interplay between miRNAs and lncRNAs: Mode of action and biological roles in plant development and stress adaptation.

Plants employ sophisticated mechanisms to control developmental processes and to cope with environmental changes at transcriptional and post-transcriptional levels. MicroRNAs (miRNAs) and long noncoding RNAs (lncRNAs), two classes of endogenous noncoding RNAs, are key regulators of gene expression in plants. Recent studies have identified the interplay between miRNAs and lncRNAs as a novel regulatory layer of gene expression in plants. On one hand, miRNAs target lncRNAs for the production of phased small interfering RNAs (phasiRNAs). On the other hand, lncRNAs serve as origin of miRNAs or regulate the accumulation or activity of miRNAs at transcription and post-transcriptional levels. Theses lncRNA-miRNA interplays are crucial for plant development, physiology and responses to biotic and abiotic stresses. In this review, we summarize recent advances in the biological roles, interaction mechanisms and computational predication methods of the interplay between miRNAs and lncRNAs in plants.

Developmental normalization of phenomics data generated by high throughput plant phenotyping systems.

BACKGROUND: Sowing time is commonly used as the temporal reference for Arabidopsis thaliana (Arabidopsis) experiments in high throughput plant phenotyping (HTPP) systems. This relies on the assumption that germination and seedling establishment are uniform across the population. However, individual seeds have different development trajectories even under uniform environmental conditions. This leads to increased variance in quantitative phenotyping approaches. We developed the Digital Adjustment of Plant Development (DAPD) normalization method. It normalizes time-series HTPP measurements by reference to an early developmental stage and in an automated manner. The timeline of each measurement series is shifted to a reference time. The normalization is determined by cross-correlation at multiple time points of the time-series measurements, which may include rosette area, leaf size, and number. RESULTS: The DAPD method improved the accuracy of phenotyping measurements by decreasing the statistical dispersion of quantitative traits across a time-series. We applied DAPD to evaluate the relative growth rate in Arabidopsis plants and demonstrated that it improves uniformity in measurements, permitting a more informative comparison between individuals. Application of DAPD decreased variance of phenotyping measurements by up to 2.5 times compared to sowing-time normalization. The DAPD method also identified more outliers than any other central tendency technique applied to the non-normalized dataset. CONCLUSIONS: DAPD is an effective method to control for temporal differences in development within plant phenotyping datasets. In principle, it can be applied to HTPP data from any species/trait combination for which a relevant developmental scale can be defined.

Proteomic dissection of the similar and different responses of wheat to drought, salinity and submergence during seed germination.

Wheat (Triticum aestivum L.) is one of the major crops worldwide and its production is inevitably subjected to various biotic/abiotic stresses during the life cycle. Drought, salinity and flooding are among the most severe abiotic stresses restricting wheat yields and could occur at very early stages such as seed germination. How wheat seed germination responds to these different stresses remains incomplete. To fill the information gap, a label-free proteomic analysis was applied to decipher the proteomic profiling of the germinating wheat seeds subjected to PEG, NaCl and submergence treatments. In total, 4295 proteins were detected, of which 465, 397 and 732 showed significant alterations in abundance under those stresses when compared with control. A common denominator found in the response observed to all three stresses are changes related to small molecule metabolic processes, and particularly in pathways associated with phenylpropanoid biosynthesis and fatty acid degradation. It was also noticeable that pathways like cysteine and methionine metabolism in the PEG or submergence treatment and starch and sucrose metabolism in the submergence treatment are specifically pronounced. Functional analysis of putative proteins participating in these pathways revealed distinct responsive patterns across different stresses. SIGNIFICANCE: Wheat (Triticum aestivum L.) is one of the most important staple crops in the world, but its growth and productivity are frequently restrained by stresses such as drought, salinity and flooding. To date, many resources have been documented to investigate how wheat responds and adapts to these individual stresses during plant development and yield formation, but little attention was paid to the understandings of the internal link between different conditions, especially during the germination process, a critical stage that determines the optimal growth of wheat. In this study, we carried out the proteome profiling of the germinating seeds of a common wheat cultivar, Chinese Spring, subjected to PEG, NaCl and submergence stresses. We found that the phenylpropanoid biosynthesis and fatty acid degradation pathways were enriched as the ubiquitous stress responses, while some pathways were stress-specific, for instance, starch and sucrose metabolism against submergence. The changes in some of the altered processes were further validated by physiological and molecular approaches. Our results suggest that the overall pathway profiles concerned with the three stresses were similar, but the specific procedures and components in each process varied greatly. The altered proteins and processes can be taken as effective candidates in future breeding and agronomic modification researches.

Mitochondrial signalling is critical for acclimation and adaptation to flooding in Arabidopsis thaliana.

Mitochondria have critical functions in the acclimation to abiotic and biotic stresses. Adverse environmental conditions lead to increased demands in energy supply and metabolic intermediates, which are provided by mitochondrial ATP production and the tricarboxylic acid (TCA) cycle. Mitochondria also play a role as stress sensors to adjust nuclear gene expression via retrograde signalling with the transcription factor (TF) ANAC017 and the kinase CDKE1 key components to integrate various signals into this pathway. To determine the importance of mitochondria as sensors of stress and their contribution in the tolerance to adverse growth conditions, a comparative phenotypical, physiological and transcriptomic characterisation of Arabidopsis mitochondrial signalling mutants (cdke1/rao1 and anac017/rao2) and a set of contrasting accessions was performed after applying the complex compound stress of submergence. Our results showed that impaired mitochondrial retrograde signalling leads to increased sensitivity to the stress treatments. The multi-factorial approach identified a network of 702 co-expressed genes, including several WRKY TFs, overlapping in the transcriptional responses in the mitochondrial signalling mutants and stress-sensitive accessions. Functional characterisation of two WRKY TFs (WRKY40 and WRKY45), using both knockout and overexpressing lines, confirmed their role in conferring tolerance to submergence. Together, the results revealed that acclimation to submergence is dependent on mitochondrial retrograde signalling, and underlying transcriptional re-programming is used as an adaptation mechanism.

Cooperative Catalysis of Chiral Guanidine and Rh2(OAc)4 in Asymmetric O-H Insertion of Carboxylic Acid: A Theoretical Investigation.

We reported a mechanistic study on asymmetric O-H insertion reaction of α-diazoester with carboxylic acid using Rh2(OAc)4/chiral guanidine-amide as the cocatalyst by density functional theory [B3LYP-D3(BJ)/def2-TZVP//B3LYP-D3(BJ)/[6-31G**, SDD] (SMD, Et2O)]. The catalytic reaction included two stages: (i) formation of Rh-carbene species, subsequently by the construction of C-O bond forming enol and (ii) chiral guanidinium salt-assisted H-transfer to the enol. In cooperative catalysis, Rh2(OAc)4 helped to form an enol intermediate via high-reactivity Rh-carbene species, while the in situ-formed guanidium carboxylate acted as a chiral proton shuttle to construct a hydrogen bonding net for the stereo-determinant protonation. The repulsions between the phenyl group of the enol intermediate and the cyclohexyl as well as the ortho-substituted isopropyl group of chiral guanidine played important roles in controlling stereoselectivity. A disadvantageous steric arrangement in si-face attack weakened the stabilizing electrostatic and orbital interaction of reacting species in the H-transfer step, enhancing the pathway to form a predominant product with R-configuration in the two competing pathways. A model was proposed to explain the asymmetric induction of chiral guanidine-amide in protonation.