D53： The Missing Link in Strigolactone Signaling

Strigolactones （SLs）, a group of small carotenoid-derived terpenoid lactones, have been recently identified as plant hormones controlling plant architecture through modulating shoot and root branching （Brewer et al., in the rhizosphere because of 2013）. SLs were first discovered their involvement in both symbiotic and parasitic interactions. Deficiencies in SL biosynthesis and perception lead to excessive growth of axillary bud, which is exemplified through various mutants such as max1, max2,     

Hydrogen sulfide,a signaling molecule in plant stress responses

Gaseous molecules, such as hydrogen sulfide(H_2S)and nitric oxide(NO), are crucial players in cellular and(patho)physiological processes in biological systems. The biological functions of these gaseous molecules, which were first discovered and identified as gasotransmitters in animals, have received unprecedented attention from plant scientists in recent decades. Researchers have arrived at the consensus that H_2S is synthesized endogenously and serves as a signaling molecule throughout the plant life cycle.However, the mechanisms of H_2S action in redox biology is still largely unexplored. This review highlights what we currently know about the characteristics and biosynthesis of H_2S in plants. Additionally,we summarize the role of H_2S in plant resistance to abiotic stress. Moreover, we propose and discuss possible redox-dependent mechanisms by which H_2S regulates plant physiology.     

New Strigolactone Analogs as Plant Hormones with Low Activities in the Rhizosphere

Strigolactones （SLs） are known not only as plant hormones, but also as rhizosphere signals for establishing symbiotic and parasitic interactions. The design of new specific SL analogs is a challenging goal in understanding the basic plant biology and is also useful to control plant architectures without favoring the development of parasitic plants. Two different molecules （23 （3＇-methyI-GR24）, 31 （thia-3＇-methyl-debranone-like molecule）） already described, and a new one （AR36）, for which the synthesis is presented, are biologically compared with the well-known GR24 and the recently identified CISA-1. These different structures emphasize the wide range of parts attached to the D-ring for the bioactivity as a plant hormone. These new compounds possess a common dimethylbutenolide motif but their structure varies in the ABC part of the molecules： 23 has the same ABC part as GR24, while 31 and AR36 carry, respectively, an aromatic ring and an acyclic carbon chain. Detailed information is given for the bioactivity of such derivatives in strigolactone synthesis or in perception mutant plants （pea rmsl and rms4, Arabidopsis max2 and, max4） for different hormonal functions along with their action in the rhizosphere on arbuscular mycorrhizal hyphal growth and parasitic weed germination.     

The human leucocyte differentiation antigens （HLDA） workshops： the evolving role of antibodies in research, diagnosis and therapy

The 8^th International Workshop on Human Leucocyte Differentiation Antigens （chaired by HZ and managed by BS） was run over a 4-year period and culminated in a conference in December 2004. Here we review the achievements of the HLDA Workshops and provide links to information on CD molecules and antibodies against them, including the 93 new CDs assigned in the 8^th Workshop. We consider what remains to be achieved （including an estimate of the number of leucocyte surface molecules still to be discovered）, and how the field can best move forward.     

Signaling events during initiation of arbuscular mycorrhizal symbiosis

Under nutrient‐limiting conditions, plants will enter into symbiosis with arbuscular mycorrhizal(AM) fungi for the enhancement of mineral nutrient acquisition from the surrounding soil. AM fungi live in close, intracellular association with plant roots where they transfer phosphate and nitrogen to the plant in exchange for carbon. They are obligate fungi,relying on their host as their only carbon source. Much has been discovered in the last decade concerning the signaling events during initiation of the AM symbiosis, including the identification of signaling molecules generated by both partners. This signaling occurs through symbiosis‐specific gene products in the host plant, which are indispensable for normal AM development. At the same time, plants have adapted complex mechanisms for avoiding infection by pathogenic fungi, including an innate immune response to general microbial molecules, such as chitin present in fungal cell walls. How it is that AM fungal colonization is maintained without eliciting a defensive response from the host is still uncertain. In this review, we present a summary of the molecular signals and their elicited responses during initiation of the AM symbiosis, including plant immune responses and their suppression.     

A Rapid Phytohormone and Phytoalexin Screening Method for Physiological Phenotyping

Dear Editor, Phytohormones have been described as essential regula- tors of various processes throughout plant life, forming a strong interactive network. Because of this important func- tion, they are central and integrative modulators form- ing a physiological key interface between plant responses and primary parameters such as genotype, environmental conditions, and developmental status. Consequently, the determination of the phytohormone signature as a key physiological parameter is necessary to understand the correlations between genotype and phenotype, as well as the influence of exogenous modulations on the phenotype （Yin et al., 2004）. Thus, evaluation of the phytohormone signature has to be considered for physiological phenotyp- ing, especially for the improvement of crops or developing strategies for plant protection. This includes the important trait plant immunity, which is determined also by distinct and fine-tuned modulations of phytohormones （Robert- Seilaniantz et al., 2011）.     

Redox Changes during the Legume-Rhizobium Symbiosis

Reactive Oxygen Species （ROS） are continuously produced as a result of aerobic metabolism or in response to biotic and abiotic stresses. ROS are not only toxic by-products of aerobic metabolism, but are also signaling molecules involved in plant growth and environmental adaptation. Antioxidants can protect the cell from oxidative damage by scavenging the ROS. Thus, they play an important role in optimizing cell function by regulating cellular redox state and modifying gene expression. This article aims to review recent studies highlighting the role of redox signals in establishing and maintaining symbiosis between rhizobia and legumes.     

Improvement of plant abiotic stress tolerance through modulation of the polyamine pathway FA简

Polyamines （mainly putrescine （Put）, spermidine （Spd）, and spermine （Spin）） have been widely found in a range of physiological processes and in almost all diverse environ- mental stresses. In various plant species, abiotic stresses modulated the accumulation of polyamines and related gene expression. Studies using loss-of-function mutants and transgenic overexpression plants modulating polyamine metabolic pathways confirmed protective roles of polyamines during plant abiotic stress responses, and indicated the possibility to improve plant tolerance through genetic manipulation of the polyamine pathway. Additionally, puta- tive mechanisms of polyamines involved in plant abiotic stress tolerance were thoroughly discussed and crosstalks among polyamine, abscisic acid, and nitric oxide in plant responses to abiotic stress were emphasized. Special attention was paid to the interaction between polyamine and reactive oxygen species, ion channels, amino acid and carbon metabolism, and other adaptive responses. Further studies are needed to elucidate the polyamine signaling pathway, especially polyamine-regulated downstream tar- gets and the connections between polyamines and other stress responsive molecules.     

Hydrogen Peroxide in Plants： a Versatile Molecule of the Reactive Oxygen Species Network

Plants often face the challenge of severe environmental conditions, which include various biotic and abiotic stresses that exert adverse effects on plant growth and development. During evolution, plants have evolved complex regulatory mechanisms to adapt to various environmental stressors. One of the consequences of stress is an increase in the cellular concentration of reactive oxygen species （ROS）, which are subsequently converted to hydrogen peroxide （H2O2）. Even under normal conditions, higher plants produce ROS during metabolic processes. Excess concentrations of ROS result in oxidative damage to or the apoptotic death of cells. Development of an antioxidant defense system in plants protects them against oxidative stress damage. These ROS and, more particularly, H2O2, play versatile roles in normal plant physiological processes and in resistance to stresses. Recently, H2O2 has been regarded as a signaling molecule and regulator of the expression of some genes in cells. This review describes various aspects of H2O2 function, generation and scavenging, gene regulation and cross-links with other physiological molecules during plant growth, development and resistance responses.     

Cysteine and Cysteine-Related SignalingPathways in Arabidopsis thaliana

Cysteine occupies a central position in plant metabolism because it is a reduced sulfur donor moleculeinvolved in the synthesis of essential biomolecules and defense compounds. Moreover, cysteine per se and its deriva-tive molecules play roles in the redox signaling of processes occurring in various cellular compartments. Cysteine issynthesized during the sulfate assimilation pathway via the incorporation of sulfide to O-acetylserine, catalyzed byO-acetylserine（thiol）lyase （OASTL）. Plant cells contain OASTLs in the mitochondria, chloroplasts, and cytosol, resultingin a complex array of isoforms and subcellular cysteine pools, in recent years, significant progress has been made inArabidopsis, in determining the specific roles of the OASTLs and the metabolites produced by them. Thus, the dis-covery of novel enzymatic activities of the less-abundant, like DES1 with L-cysteine desulfhydrase activity and SCSwith S-sulfocysteine synthase activity, has provided new perspectives on their roles, besides their metabolic functions.Thereby, the research has been demonstrated that cytosolic sulfide and chloroplastic S-sulfocysteine act as signalingmolecules regulating autophagy and protecting the photosystems, respectively. In the cytosol, cysteine plays an essentialrole in plant immunity; in the mitochondria, this molecule plays a central role in the detoxification of cyanide, which isessential for root hair development and plant responses to pathogens.     

DESCRIPTION OF A KUBANOCHOERUS SKULL FROM TONGXIN, NINGXIA

<正> A rich Middle Miocene mammalian fauna was discovered in a gully named Maerzuizi Gou, Tongxin County, Ningxia Hui Autonomous Region, in the winter of 1985. Among the fossils is a well preserved skull evidently belonging to Kubanochoerus. It is the third and, as far as we know, the best preserved of its kind so far in the world. A careful study of the skull has enabled us not only to review all the fossils previously discovered and assigned either to Listriodon or to Bunolistriodon in China, but also to clarify in certain degree the evolutionary trend and the classification of that particular group.     

MicroRNAs in Common Human Diseases

MicroRNAs (miRNAs) are a class of short non-coding RNA molecules that have attracted tremendous attention from the biological and biomedical research communities over the past decade. With over 1900 miRNAs discovered in humans to date, many of them have already been implicated in common human disorders. Facilitated by high-throughput genomics and bioinformatics in conjunction with traditional molecular biology techniques and animal models, miRNA research is now positioned to make the transition from laboratories to clinics to deliver profound benefits to public health. Herein, we overview the progress of miRNA research related to human diseases, as well as the potential for miRNA to becoming the next generation of diagnostics and therapeutics.     

Essential roles of four-carbon backbone chemicals in the control of metabolism

The increasing incidence of obesity worldwide and its related cardiometabolic complications is an urgent public health problem. While weight gain results from a negative balance between the energy expenditure and calorie intake, recent research has demonstrated that several small organic molecules containing a four-carbon backbone can modulate this balance by favoring energy expenditure, and alleviating endoplasmic reticulum stress and oxidative stress. Such small molecules include the bacterially produced short chain fatty acid butyric acid, its chemically produced derivative 4-phenylbutyric acid, the main ketone body D-β-hydroxybutyrate- synthesized by the liver- and the recently discovered myokine β-aminoisobutyric acid. Conversely, another butyraterelated molecule, α-hydroxybutyrate, has been found to be an early predictor of insulin resistance and glucose intolerance. In this minireview, we summarize recent advances in the understanding of the mechanism of action of these molecules, and discuss their use as therapeutics to improve metabolic homeostasis or their detection as early biomarkers of incipient insulin resistance.     

Ligand Perception,Activation, and Early Signaling of Plant Steroid Receptor Brassinosteroid Insensitive

Leucine-rich repeat receptor-like kinases （LRR-RLKs） belong to a large group of cell surface proteins involved in many aspects of plant development and environmental responses in both monocots and dicots. Brassinosteroid insensitive 1 （BRI1）, a member of the LRR X subfamily, was first identified through several forward genetic screenings for mutants insensitive to brassinosteroids （BRs）, which are a class of plant-specific steroid hormones. Since its identification, BRI1 and its homologs had been proved as receptors perceiving BRs and initiating BR signaling. The co-receptor BRIl-associated kinase 1 and its homologs, and other BRI1 interacting proteins such as its inhibitor BRI1 kinase inhibitor I （BKI1） were identified by genetic andbiochemical approaches. The detailed mechanisms of BR perception by BRI1 and the activation of BRI1 receptor complex have also been elucidated. Moreover, several mechanisms for termination of the activated BRI1 signaling were also discovered. In this review, we will focus on the recent advances on the mechanism of BRI1 phosphorylation and activation, the regulation of its receptor complex, the structure basis of BRI1 ectodomain and BR recognition, its direct substrates, and the termination of the activated BRI1 receptor complex.     

Dihydroactinidiolide,a High Light-Induced 13-Carotene Derivative that Can Regulate Gene Expression and Photoacclimation in Arabidopsis

Dear Editor,
The physiological functions of carotenoids in plants go beyond their traditional roles as accessory light-har- vesting pigments, natural colorants, and quenchers of tri- plet chlorophyll and singlet oxygen （102）. Recent studies have indeed emphasized the functional role of molecules derived from carotenoids as phytohormones （Ruyter-Spira et al., 20β） or messengers in stress signaling pathways （Havaux, 2014）. In particular, chemical quenching of 102 by carotenoids within the photosystems involves oxidation of the carotenoid molecules, generating a variety of oxi- dized products （Ramel et al., 2012）. β-Cyclocitral, a volatile C7 derivative of β-carotene, is one such molecule produced during high light stress, which was found to induce changes in the expression of 102-responsive genes （Ramel et al., 2012）. Moreover, the β-cyclocitral-dependent gene repro- gramming was associated with an increased tolerance of the plants to photooxidative stress. These effects appeared to be specific to β-cyclocitral since they were not observed with β-ionone, a C9-oxidized derivative of ~-carotene, which was not able to induce or repress the expression of 1O2 gene markers. Based on those results, it was pro- posed that β-cyclocitral is a plastid messenger involved in the chloroplast-to-nucleus 1O2 signaling pathway lead- ing to acclimation to high light stress （Ramel et al., 2012）. However, in vitro 102 oxidation of β-carotene is known to produce other volatile compounds besides β-cyclocitral and IB-ionone, such as dihydroactinidiolide （dhA, Figure 1A） and a-ionene （Ramel et al., 2012）. The dhA molecule is a lac- tone （cyclic ester） resulting from the secondary oxidation of β-ionone through the intermediate 5,6-epoxy-β-ionone （Havaux, 2014）. Both dhA and o-ionene were detected in plant leaves and fruits （e.g. Del Mar Caja et al., 2009; Ramel et al., 2012）. Interestingly, dhA, but not o-ionene, was reported to accumulate in Arabidopsis leaves under hiclh liclht str     

New GATEWAY vectors for High Throughput Analyses of Protein-Protein Interactions by Bimolecular Fluorescence Complementation

Complex protein interaction networks constitute plant metabolic and signaling systems. Bimolecular fluorescence complementation （BiFC） is a suitable technique to investigate the formation of protein complexes and the localization of protein-protein interactions in planta. However, the generation of large plasmid collections to facilitate the exploration of complex interaction networks is often limited by the need for conventional cloning techniques. Here, we report the implementation of a GATEWAY vector system enabling large-scale combination and investigation of candidate proteins in BiFC studies. We describe a set of 12 GATEWAY-compatible BiFC vectors that efficiently permit the combination of candidate protein pairs with every possible N-or C-terminal sub-fragment of S（CFP）3A or Venus, respectively, and enable the performance of multicolor BiFC （mcBiFC）. We used proteins of the plant molybdenum metabolism, in that more than 20 potentially interacting proteins are assumed to form the cellular molybdenum network, as a case study to establish the functionality of the new vectors. Using these vectors, we report the formation of the molybdopterin synthase complex by interaction of Arabidopsis proteins Cnx6 and Cnx7 detected by BiFC as well as the simultaneous formation of Cnx6/Cnx6 and Cnx6/Cnx7 complexes revealed by mcBiFC. Consequently, these GATEWAY-based BiFC vector systems should significantly facilitate the large-scale investigation of complex regulatory networks in plant cells.     

A Start Point for Extracellular Nucleotide Signaling

A START POINT FOR EXTRACELLULAR NUCLEOTIDE SIGNALING
The recent discovery of a plant receptor for extracellu- lar nucleotides, reported by Choi et al. （2014）, is a major breakthrough that had been anticipated for over a dec- ade. Plants release ATP into their extracellular matrix （ECM） during growth and when they are induced by vari- ous biotic and abiotic stimuli （Clark and Roux, 2011）. That these extracellular nucleotides would activate receptors in plants was predicted by two sets of discoveries： that low- and sub-micromolar ATP could induce increases in [Ca2＋]cyt, NO, and superoxide signaling intermediates that led to downstream growth, stomatal, and defense responses, and that these changes could be blocked by antagonists that blocked extracellular nucleotide receptors in animals （Demidchik et al., 2003; Song et al., 2006; Clark et al., 2011; Demidchik et al., 2009, 2011）. Although mammalian biolo- gists had discovered two classes of receptors for extracel- lular nucleotides （P2X and P2Y） decades ago （Burnstock, 2007）, there were no plant proteins obviously similar to these in any sequence data available. Clearly, if there were plant purinoceptors, they would be different from the mammalian receptors, and they could not be discovered by motif searches.     

Plant Terpenoids： Biosynthesis and Ecological Functions

Among plant secondary metabolites terpenolds are a structurally most diverse group; they function as phytoalexins In plant direct defense, or as signals In Indirect defense responses which involves herbivores and their natural enemies. In recent years, more and more attention has been paid to the Investigation of the ecological role of plant terpenolds. The biosynthesis pathways of monoterpenes, sesquiterpenes, and diterpenes Include the synthesis of C5 precursor isopentenyl diphosphate （IPP） and Its allylic isomer dlmethylallyl dlphosphate （DMAPP）, the synthesis of the immediate diphosphate precursors, and the formation of the diverse terpenoids. Terpene synthases （TPSs） play a key role In volatile terpene synthesis. By expression of the TPS genes, significant achievements have been made on metabolic engineering to Increase terpenoid production. This review mainly summarizes the recent research progress In elucidating the ecological role of terpenoids and characterization of the enzymes Involved in the terpenold biosynthesis. Spatial and temporal regulations of terpenoids metabolism are also discussed.