The glycolytic enzyme, phosphoglycerate mutase, has critical roles in stomatal movement, vegetative growth, and pollen production in Arabidopsis thaliana

Stomatal movements require massive changes in guard cell osmotic content, and both stomatal opening and stomatal closure have been shown to be energy-requiring processes. A possible role for glycolysis in contributing to the energetic, reducing requirements, or signalling processes regulating stomatal movements has not been investigated previously. Glycolysis, oxidization of glucose to pyruvate, is a central metabolic pathway and yields a net gain of 2 ATP and 2 NADH. 2,3-biphosphoglycerate-independent phosphoglycerate mutase (iPGAM) is a key enzymatic activity in glycolysis and catalyses the reversible interconversion of 3-phosphoglycerate to 2-phosphoglycerate. To investigate functions of iPGAMs and glycolysis in stomatal function and plant growth, Arabidopsis insertional mutants in At1g09780 and At3g08590, both of which have been annotated as iPGAMs on the basis of sequence homology, were identified and characterized. While single mutants were indistinguishable from the wild type in all plant phenotypes assayed, double mutants had no detectable iPGAM activity and showed defects in blue light-, abscisic acid-, and low CO2-regulated stomatal movements. Vegetative plant growth was severely impaired in the double mutants and pollen was not produced. The data demonstrate that iPGAMs and glycolytic activity are critical for guard cell function and fertility in Arabidopsis

Deficiency in the Phosphorylated Pathway of Serine Biosynthesis Perturbs Sulfur Assimilation

Anoman AD, Flores-Tornero M, Benstein RM, et al. Deficiency in the Phosphorylated Pathway of Serine Biosynthesis Perturbs Sulfur Assimilation. PLANT PHYSIOLOGY. 2019;180(1):153-170.Although the plant Phosphorylated Pathway of L-Ser Biosynthesis (PPSB) is essential for embryo and pollen development, and for root growth, its metabolic implications have not been fully investigated. A transcriptomics analysis of Arabidopsis (Arabidopsis thaliana) PPSB-deficient mutants at night, when PPSB activity is thought to be more important, suggested interaction with the sulfate assimilation process. Because sulfate assimilation occurs mainly in the light, we also investigated it in PPSB-deficient lines in the day. Key genes in the sulfate starvation response, such as the adenosine 5'phosphosulfate reductase genes, along with sulfate transporters, especially those involved in sulfate translocation in the plant, were induced in the PPSB-deficient lines. However, sulfate content was not reduced in these lines as compared with wild-type plants; besides the glutathione (GSH) steady-state levels in roots of PPSB-deficient lines were even higher than in wild type. This suggested that PPSB deficiency perturbs the sulfate assimilation process between tissues/organs. Alteration of thiol distribution in leaves from different developmental stages, and between aerial parts and roots in plants with reduced PPSB activity, provided evidence supporting this idea. Diminished PPSB activity caused an enhanced flux of S-35 into thiol biosynthesis, especially in roots. GSH turnover also accelerated in the PPSB-deficient lines, supporting the notion that not only biosynthesis, but also transport and allocation, of thiols were perturbed in the PPSB mutants. Our results suggest that PPSB is required for sulfide assimilation in specific heterotrophic tissues and that a lack of PPSB activity perturbs sulfur homeostasis between photosynthetic and nonphotosynthetic tissues

Comparative study of GC-MS characterization, antioxidant activity and hyaluronidase inhibition of different species of Lavandula and Thymus essential oils

The chemical compositions of essential oils of Lavandula angustifolia, Lavandula latifolia, Lavandula hybrida cultivar Grosso and cultivar Super, Thymus zygis with high proportions of thymol and linalool and Thymus hyemalis, from Murcia country (Spain), were studied in relative (%), absolute (mM) and chiral concentrations by GC/MS. Hyaluronidase inhibition and antioxidant activities of the essential oils were evaluated using ABTS(center dot+), DPPH center dot, ORAC, chelating power, hydroxyl radical, nitric oxide, TBARS and reducing power assays. Linalool and linalyl acetate were the most abundant components in the Lavandula genus whereas thymol, linalool and 1,8-cineole were the most abundant molecules in the respective Thymus species. Chiral determination of the main components showed (+)-enantiomers like terpinen-4-ol, beta-pinene, borneol and a-terpineol and (-)-enantiomers like linalool, linalyl acetate and camphene in Lavandula sp. In the case of Thymus sp. (+)-enantiomers like a-pinene, limonene, terpinen-4-ol and a-terpineol and (-)-enantiomers like borneol were found. Essential oils containing thymol were found especially powerful in all assays but chelating power, ORAC and hydroxyl radical scavenging assays. The capacity for inhibiting hyaluronidase showed that T. zygis with a high proportion of thymol was the most effective inhibitor. Essential oils containing thymol and linalool/linalyl acetate have a potential use as antioxidant agents. Thymol shows strong inhibition of hyaluronidase. Copyright (C) 2015 John Wiley & Sons, Ltd

Species-Specific Expansion and Molecular Evolution of the 3-hydroxy-3-methylglutaryl Coenzyme A Reductase (HMGR) Gene Family in Plants

Kazakh dandelion (Taraxacum kok-saghyz, Tk) is a rubber-producing plant currently being investigated as a source of natural rubber for industrial applications. Like many other isoprenoids, rubber is a downstream product of the mevalonate pathway. The 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) enzyme catalyzes the conversion of 3-hydroxy-3-methylglutaryl-CoA to mevalonic acid, a key regulatory step in the MVA pathway. Such regulated steps provide targets for increases in isoprenoid and rubber contents via genetic engineering to increase enzyme activities. In this study, we identify a TkHMGR1 gene that is highly expressed in the roots of Kazakh dandelion, the main tissue where rubber is synthesized and stored. This finding paves the way for further molecular and genetic studies of the TkHMGR1 gene, and its role in rubber biosynthesis in Tk and other rubber-producing plants

The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase 1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age  6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score  652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc = 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N = 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701

Serine in plants: biosynthesis, metabolism, and functions

Serine (Ser) has a fundamental role in metabolism and signaling in living organisms. In plants, the existence of different pathways of Ser biosynthesis has complicated our understanding of this amino acid homeostasis. The photorespiratory glycolate pathway has been considered to be of major importance, whereas the nonphotorespiratory phosphorylated pathway has been relatively neglected. Recent advances indicate that the phosphorylated pathway has an important function in plant metabolism and development. Plants deficient in this pathway display developmental defects in embryos, male gametophytes, and roots. We propose that the phosphorylated pathway is more important than was initially thought because it is the only Ser source for specific cell types involved in developmental events. Here, we discuss its importance as a link between metabolism and development in plants

Functional Characterization of the Plastidial 3-Phosphoglycerate Dehydrogenase Family in Arabidopsis

This work contributes to unraveling the role of the phosphorylated pathway of serine (Ser) biosynthesis in Arabidopsis (Arabidopsis thaliana) by functionally characterizing genes coding for the first enzyme of this pathway, 3-phosphoglycerate dehydrogenase (PGDH). We identified two Arabidopsis plastid-localized PGDH genes (3-PGDH and EMBRYO SAC DEVELOPMENT ARREST9 [EDA9]) with a high percentage of amino acid identity with a previously identified PGDH. All three genes displayed a different expression pattern indicating that they are not functionally redundant. pgdh and 3-pgdh mutants presented no drastic visual phenotypes, but eda9 displayed delayed embryo development, leading to aborted embryos that could be classified as early curled cotyledons. The embryo-lethal phenotype of eda9 was complemented with an EDA9 complementary DNA under the control of a 35S promoter (Pro-35S:EDA9). However, this construct, which is poorly expressed in the anther tapetum, did not complement mutant fertility. Microspore development in eda9.1eda9.1 Pro-35S:EDA9 was arrested at the polarized stage. Pollen from these lines lacked tryphine in the interstices of the exine layer, displayed shrunken and collapsed forms, and were unable to germinate when cultured in vitro. A metabolomic analysis of PGDH mutant and overexpressing plants revealed that all three PGDH family genes can regulate Ser homeostasis, with PGDH being quantitatively the most important in the process of Ser biosynthesis at the whole-plant level. By contrast, the essential role of EDA9 could be related to its expression in very specific cell types. We demonstrate the crucial role of EDA9 in embryo and pollen development, suggesting that the phosphorylated pathway of Ser biosynthesis is an important link connecting primary metabolism with development