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Benye Liu

Bio: Benye Liu is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Artemisia annua & Artemisinin. The author has an hindex of 22, co-authored 46 publications receiving 1859 citations. Previous affiliations of Benye Liu include Braunschweig University of Technology.

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Journal ArticleDOI
TL;DR: Transient expression experiments in agroinfiltrated Nicotiana benthamiana and A. annua leaves showed that AaWRKY1 protein transactivated the ADSpro2 promoter activity by binding to the W-box of the promoter; disruption of theW-box abolished the activation.
Abstract: Amorpha-4,11-diene synthase (ADS) of Artemisia annua catalyzes the conversion of farnesyl diphosphate into amorpha-4,11-diene, the first committed step in the biosynthesis of the antimalarial drug artemisinin. The promoters of ADS contain two reverse-oriented TTGACC W-box cis-acting elements, which are the proposed binding sites of WRKY transcription factors. A full-length cDNA (AaWRKY1) was isolated from a cDNA library of the glandular secretory trichomes (GSTs) in which artemisinin is synthesized and sequestered. AaWRKY1 encodes a 311 amino acid protein containing a single WRKY domain. AaWRKY1 and ADS genes were highly expressed in GSTs and both were strongly induced by methyl jasmonate and chitosan. Transient expression analysis of the AaWRKY1-GFP (green fluorescent protein) reporter revealed that AaWRKY1 was targeted to nuclei. Biochemical analysis demonstrated that the AaWRKY1 protein was capable of binding to the W-box cis-acting elements of the ADS promoters, and it demonstrated transactivation activity in yeast. Co-expression of the effector construct 35S::AaWRKY1 with a reporter construct ADSpro1::GUS greatly activated expression of the GUS (beta-glucuronidase) gene in stably transformed tobacco. Furthermore, transient expression experiments in agroinfiltrated Nicotiana benthamiana and A. annua leaves showed that AaWRKY1 protein transactivated the ADSpro2 promoter activity by binding to the W-box of the promoter; disruption of the W-box abolished the activation. Transient expression of AaWRKY1 cDNA in A. annua leaves clearly activated the expression of the majority of artemisinin biosynthetic genes. These results strongly suggest the involvement of the AaWRKY1 transcription factor in the regulation of artemisinin biosynthesis, and indicate that ADS is a target gene of AaWRKY1 in A. annua.

279 citations

Journal ArticleDOI
TL;DR: Results suggest that salicylic acid induces artemisinin biosynthesis in Artemisia annua L. annua in at least two ways: by increasing the conversion of dihydroartemisinic acid into artemis inin caused by the burst of ROS, and by up-regulating the expression of genes involved in artemisine biosynthesis.
Abstract: This paper provides evidence that salicylic acid (SA) can activate artemisinin biosynthesis in Artemisia annua L. Exogenous application of SA to A. annua leaves was followed by a burst of reactive oxygen species (ROS) and the conversion of dihydroartemisinic acid into artemisinin. In the 24 h after application, SA application led to a gradual increase in the expression of the 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) gene and a temporary peak in the expression of the amorpha-4,11-diene synthase (ADS) gene. However, the expression of the farnesyl diphosphate synthase (FDS) gene and the cytochrome P450 monooxygenase (CYP71AV1) gene showed little change. At 96 h after SA (1.0 mM) treatment, the concentration of artemisinin, artemisinic acid and dihydroartemisinic acid were 54, 127 and 72% higher than that of the control, respectively. Taken together, these results suggest that SA induces artemisinin biosynthesis in at least two ways: by increasing the conversion of dihydroartemisinic acid into artemisinin caused by the burst of ROS, and by up-regulating the expression of genes involved in artemisinin biosynthesis.

160 citations

Journal ArticleDOI
TL;DR: The isotopologue data confirm the previously proposed mechanisms for the cyclization of (E,E)-FPP to amorphadiene and its oxidative conversion to artemisinin and support deprotonation of a terminal allyl cation intermediate as the final step in the enzymatic conversion of FPP to amorpha-4,11-diene.

133 citations

Journal ArticleDOI
27 Jul 2012-Planta
TL;DR: Results suggest that CrAS and CrAO are involved in the pentacyclic triterpene biosynthesis in C. roseus.
Abstract: Catharanthus roseus is an important medicinal plant and the sole commercial source of monoterpenoid indole alkaloids (MIA), anticancer compounds. Recently, triterpenoids like ursolic acid and oleanolic acid have also been found in considerable amounts in C. roseus leaf cuticular wax layer. These simple pentacyclic triterpenoids exhibit various pharmacological activities such as anti-inflammatory, anti-tumor and anti-microbial properties. Using the EST collection from C. roseus leaf epidermome ( http://www.ncbi.nlm.nih.gov/dbEST ), we have successfully isolated a cDNA (CrAS) encoding 2,3-oxidosqualene cyclase (OSC) and a cDNA (CrAO) encoding amyrin C-28 oxidase from the leaves of C. roseus. The functions of CrAS and CrAO were analyzed in yeast (Saccharomyces cerevisiae) systems. CrAS was characterized as a novel multifunctional OSC producing α- and β-amyrin in a ratio of 2.5:1, whereas CrAO was a multifunctional C-28 oxidase converting α-amyrin, β-amyrin and lupeol to ursolic-, oleanolic- and betulinic acids, respectively, via a successive oxidation at the C-28 position of the substrates. In yeast co-expressing CrAO and CrAS, ursolic- and oleanolic acids were detected in the yeast cell extracts, while the yeast cells co-expressing CrAO and AtLUP1 from Arabidopsis thaliana produced betulinic acid. Both CrAS and CrAO genes show a high expression level in the leaf, which was consistent with the accumulation patterns of ursolic- and oleanolic acids in C. roseus. These results suggest that CrAS and CrAO are involved in the pentacyclic triterpene biosynthesis in C. roseus.

117 citations

Journal ArticleDOI
TL;DR: Benzophenone derivatives, such as polyprenylated benzoylphloroglucinols and xanthones, are biologically active secondary metabolites that are catalyzed by benzophenone synthase that has been cloned from cell cultures of Hypericum androsaemum and is grouped together with the PKSs that functionally differ from CHS.
Abstract: Summary Benzophenone derivatives, such as polyprenylated benzoylphloroglucinols and xanthones, are biologically active secondary metabolites. The formation of their C13 skeleton is catalyzed by benzophenone synthase (BPS; EC 2.3.1.151) that has been cloned from cell cultures of Hypericum androsaemum. BPS is a novel member of the superfamily of plant polyketide synthases (PKSs), also termed type III PKSs, with 53–63% amino acid sequence identity. Heterologously expressed BPS was a homodimer with a subunit molecular mass of 42.8 kDa. Its preferred starter substrate was benzoyl-CoA that was stepwise condensed with three malonyl-CoAs to give 2,4,6-trihydroxybenzophenone. BPS did not accept activated cinnamic acids as starter molecules. In contrast, recombinant chalcone synthase (CHS; EC 2.3.1.74) from the same cell cultures preferentially used 4-coumaroyl-CoA and also converted CoA esters of benzoic acids. The enzyme shared 60.1% amino acid sequence identity with BPS. In a phylogenetic tree, the two PKSs occurred in different clusters. One cluster was formed by CHSs including the one from H. androsaemum. BPS grouped together with the PKSs that functionally differ from CHS. Site-directed mutagenesis of amino acids shaping the initiation/elongation cavity of CHS yielded a triple mutant (L263M/F265Y/S338G) that preferred benzoyl-CoA over 4-coumaroyl-CoA.

115 citations


Cited by
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Journal ArticleDOI
TL;DR: Important new components of jasmonate signalling including its receptor were identified, providing deeper insight into the role ofJASMONATE signalling pathways in stress responses and development.

1,868 citations

Journal ArticleDOI
TL;DR: Recent advances in the identification of upstream receptors/sensors and downstream MAPK substrates revealed the molecular mechanisms underlying MAPK functions in plant disease resistance and emerged as battlegrounds of plant-pathogen interactions.
Abstract: Mitogen-activated protein kinase (MAPK) cascades are highly conserved signaling modules downstream of receptors/sensors that transduce extracellular stimuli into intracellular responses in eukaryotes. Plant MAPK cascades play pivotal roles in signaling plant defense against pathogen attack. In this review, we summarize recent advances in the identification of upstream receptors/sensors and downstream MAPK substrates. These findings revealed the molecular mechanisms underlying MAPK functions in plant disease resistance. MAPK cascades have also emerged as battlegrounds of plant-pathogen interactions. Activation of MAPKs is one of the earliest signaling events after plant sensing of pathogen/microbe-associated molecular patterns (PAMPs/MAMPs) and pathogen effectors. MAPK cascades are involved in signaling multiple defense responses, including the biosynthesis/signaling of plant stress/defense hormones, reactive oxygen species (ROS) generation, stomatal closure, defense gene activation, phytoalexin biosynthes...

897 citations

Journal ArticleDOI
TL;DR: Transduction of recognition probably requires regulated protein degradation and results in massive changes in cellular homeostasis, including a programmed cell death known as the hypersensitive response that indicates a successful, if perhaps over-zealous, disease resistance response.
Abstract: Molecular communication between plants and potential pathogens determines the ultimate outcome of their interaction. The directed delivery of microbial molecules into and around the host cell, and the subsequent perception of these by the invaded plant tissue (or lack thereof), determines the difference between disease and disease resistance. In theory, any foreign molecule produced by an invading pathogen could act as an elicitor of the broad physiological and transcriptional re-programming indicative of a plant defense response. The diversity of elicitors recognized by plants seems to support this hypothesis. Additionally, these elicitors are often virulence factors from the pathogen recognized by the host. This recognition, though genetically as simple as a ligand-receptor interaction, may require additional host proteins that are the nominal targets of virulence factor action. Transduction of recognition probably requires regulated protein degradation and results in massive changes in cellular homeostasis, including a programmed cell death known as the hypersensitive response that indicates a successful, if perhaps over-zealous, disease resistance response.

585 citations

Journal ArticleDOI
TL;DR: Recent developments in the field of triterpene biosynthesis are reviewed, an overview of the genes and enzymes that have been identified to date are given, and strategies for discovering new triterpenes pathways are discussed.
Abstract: The triterpenes are one of the most numerous and diverse groups of plant natural products. They are complex molecules that are, for the most part, beyond the reach of chemical synthesis. Simple triterpenes are components of surface waxes and specialized membranes and may potentially act as signaling molecules, whereas complex glycosylated triterpenes (saponins) provide protection against pathogens and pests. Simple and conjugated triterpenes have a wide range of applications in the food, health, and industrial biotechnology sectors. Here, we review recent developments in the field of triterpene biosynthesis, give an overview of the genes and enzymes that have been identified to date, and discuss strategies for discovering new triterpene biosynthetic pathways.

506 citations

Journal ArticleDOI
TL;DR: The prospect of drug discovery from herbal medicines in the postgenomic era was made with the provision of future directions in this area of drug development.
Abstract: With tens of thousands of plant species on earth, we are endowed with an enormous wealth of medicinal remedies from Mother Nature. Natural products and their derivatives represent more than 50% of all the drugs in modern therapeutics. Because of the low success rate and huge capital investment need, the research and development of conventional drugs are very costly and difficult. Over the past few decades, researchers have focused on drug discovery from herbal medicines or botanical sources, an important group of complementary and alternative medicine (CAM) therapy. With a long history of herbal usage for the clinical management of a variety of diseases in indigenous cultures, the success rate of developing a new drug from herbal medicinal preparations should, in theory, be higher than that from chemical synthesis. While the endeavor for drug discovery from herbal medicines is “experience driven,” the search for a therapeutically useful synthetic drug, like “looking for a needle in a haystack,” is a daunting task. In this paper, we first illustrated various approaches of drug discovery from herbal medicines. Typical examples of successful drug discovery from botanical sources were given. In addition, problems in drug discovery from herbal medicines were described and possible solutions were proposed. The prospect of drug discovery from herbal medicines in the postgenomic era was made with the provision of future directions in this area of drug development.

486 citations