Histogram of the gene ontology classifications of annotated unigenes from the <i>W</i>. <i>ugandensis</i> transcriptome.

<p>BP, Biological process; CC, Cell component; MF, Molecular function.</p

Phylogenetic tree of terpene synthases.

<p>Phylogenetic analysis of 14 putative <i>W</i>. <i>ugandensis</i> WuTPS protein sequences with their homologs from other plants indicates that they are clustered into three main clades including: monoterpenoid synthase (WuMts), sesquiterpenoid synthase (WuSps), and diterpenoid synthase (WuDts). WarbTPS-c (ACJ46047.1, putative sesquiterpene synthase, <i>W</i>. <i>ugandensis</i>); WarbTPS-g (ACJ46048.1, putative sesquiterpene synthase, <i>W</i>. <i>ugandensis</i>); WuSps1, CL29873Contig1; WuSps2, CL29511Contig1; WuSps3, CL3178Contig1; WuSps4, CL4160Contig1; WuSps5, comp68897_c0_seq1; WuSps6, CL24969Contig1; WuSps7, CL30258Contig1; WuMts1, CL27268Contig1; WuMts2, CL27339Contig1; WuMts3, CL30385Contig1; WuMts4, CL276Contig2; WuMts5, CL1Contig9269; WuMts6, CL29966Contig1; WuMts7, CL14869Contig1; WuDts1, CL9128Contig1; WuDts2, CL28648Contig1; Citsi_Germacrene_D (XP_006494713.1, (-)-germacrene D synthase-like isoform X2, <i>Citrus sinensis</i>); Popeu_Valencene (XP_011015484.1, valencene synthase-like, <i>Populus euphratica</i>); Nelnu_Germacrene_D (XP_010258444.1, (-)-germacrene D synthase-like, <i>Nelumbo nucifera</i>); Eletr_Copaene (ADK94034.1, alpha-copaene synthase, <i>Eleutherococcus trifoliatus</i>); Gosar_Germacrene_D (KHG04103.1, (-)-germacrene D synthase, <i>Gossypium arboretum</i>); Vitvi_Germacrene_D (XP_010644711.1, (-)-germacrene D synthase, <i>Vitis vinifera</i>); Vitvi_Germacrene_A (ADR66821.1, Germacrene A synthase, <i>Vitis vinifera</i>); Citja_Elemene (BAP74389.1, delta-elemene synthase, <i>Citrus jambhiri</i>); Theca_Cadinene (EOY12648.1, Delta-cadinene synthase isozyme A, <i>Theobroma cacao</i>); Ricco_Cadinene (EEF38721.1, (+)-delta-cadinene synthase isozyme A, <i>Ricinus communis</i>); Aqusi_Guaiene (AIT75875.1, putative delta-guaiene synthase, <i>Aquilaria sinensis</i>); Vitvi_Caryophyllene (AEP17005.1, (E)-beta-caryophyllene synthase, <i>Vitis vinifera</i>); Maggr_Cubebene (ACC66281.1, beta-cubebene synthase, <i>Magnolia grandiflora</i>); Cinos_Linalool (AFK09265.1, S-(+)-linalool synthase, <i>Cinnamomum osmophloeum</i>); Nelnu_Nerolidol (XP_010248179.1, (3S,6E)-nerolidol synthase 1-like, <i>Nelumbo nucifera</i>); Vitvi_Nerolidol (XP_010646919.1, (3S,6E)-nerolidol synthase 1, chloroplastic-like isoform X1, <i>Vitis vinifera</i>); Vitvi_Linalool (ADR74212.1, (3S)-linalool/(E)-nerolidol synthase, <i>Vitis vinifera</i>); Actpo_Linalool (ADD81295.1, linalool synthase, <i>Actinidia polygama</i>); Nelnu_Ent-copalyl (XP_010277558.1, ent-copalyl diphosphate synthase, chloroplastic-like, <i>Nelumbo nucifera</i>); Theca_Ent-copalyl (XP_007050589.1, Copalyl diphosphate synthase, <i>Theobroma cacao</i>); Morno_Ent-copalyl (XP_010090409.1, Ent-copalyl diphosphate synthase, <i>Morus notabilis</i>); Gosar_Ent-copalyl (KHG01750.1, Ent-copalyl diphosphate synthase, chloroplastic, <i>Gossypium arboreum</i>); Nelnu_Ent-kaurene (XP_010260722.1, ent-kaur-16-ene synthase, chloroplastic isoform X1, <i>Nelumbo nucifera</i>); Phoda_Ent-kaurene (XP_008809130.1, ent-kaur-16-ene synthase, chloroplastic, <i>Phoenix dactylifera</i>); Ricico_Ent-kaurene (XP_002533694.1, Ent-kaurene synthase B, chloroplast precursor, <i>Ricinus communis</i>); Popeu_Ent-kaurene (XP_011014299.1, ent-kaur-16-ene synthase, chloroplastic, <i>Populus euphratica</i>); Nicta_Epi-Aristolochene (3M02.A, 5-Epi-Aristolochene Synthase, <i>Nicotiana tabacum</i>); Soltu_Vetispiradiene (Q9XJ32.1, vetispiradiene synthase 1, <i>Solanum tuberosum</i>); Litcu_Ocimene (AEJ91554.1, trans-ocimene synthase, <i>Litsea cubeba</i>); Litcu_Thujene (AEJ91555.1, alpha-thujene synthase, <i>Litsea cubeba</i>); Citli_Limonene (AAM53946.1, (+)-limonene synthase 2, <i>Citrus limon</i>); Vitvi_Ocimene/Myrcene (ADR74206.1, (E)-beta-ocimene/myrcene synthase, <i>Vitis vinifera</i>); Queil_Pinene (CAK55186.1, pinene synthase, <i>Quercus ilex</i>).</p

Summary of unigenes related to lipid and terpenoid metabolism.

<p>Summary of unigenes related to lipid and terpenoid metabolism.</p

Statistic of sequencing and <i>de novo</i> assembling of transcriptome in <i>W</i>. <i>ugandensis</i>.

<p>Statistic of sequencing and <i>de novo</i> assembling of transcriptome in <i>W</i>. <i>ugandensis</i>.</p

qRT-PCR analysises.

<p>qRT-PCRwas performed to validate the 12 differentially expressed unigenes related to terpenoid biosynthesis and/or unsaturated fatty acid metabolisms. The gene names, serial numbers and primer sequences used for qRT-PCR analysis are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0135724#pone.0135724.s012" target="_blank">S8 Table</a>.</p

Statistics of annotations for assembled unigenes in <i>W</i>. <i>ugandensis</i>.

<p>^a The percent of annotated unigenes in the total 72591 assembled unigene.</p><p>Statistics of annotations for assembled unigenes in <i>W</i>. <i>ugandensis</i>.</p

The phytochemical analysis of terpenoid and fatty acid compositions in <i>W</i>. <i>ugandensis</i> bark and leaf.

<p>The relative content of monoterpenes (A), sesquiterpenes (B), and fatty acid compositions (C) were shown.</p

Putative structural genes involved in terpenoid backbone biosynthesis pathway.

<p>The values in the bracket indicate the number of unigenes in the corresponding gene families. ACCT, acetyl-CoA C-acetyltransferase; HMGS, hydroxymethylglutaryl-CoA synthase; HMGR, hydroxymethylglutaryl-CoA reductase; MVK, mevalonate kinase; PMK, phosphomevalonate kinase; MVD, mevalonate diphosphate decarboxylase; DXS, 1-deoxy-D-xylulose-5-phosphate synthase; DXR, 1-deoxy-D-xylulose-5-phosphate reductoisomerase; MCT, 2-C-methyl-D-erythritol 4-phosphate cytidylyltransferase; CMK, 4-diphosphocytidyl-2-C-methyl-D-erythritol kinase; MECPS, 2-C-methyl-D-erythritol 2,4-cyclodiphosphate synthase; HDR, 4-hydroxy-3-methylbut-2-enyl diphosphate reductase; HDS, (E)-4-hydroxy-3-methylbut-2-enyl-diphosphate synthase; IDI, isopentenyl-diphosphate delta-isomerase; GPPS, geranyl diphosphate synthase; FPPS, farnesyl diphosphate synthase; STS, Sesquiterpenoid synthase; MTS, Monoterpenoid synthase.</p

Enhancing Two-Electron Reaction Contribution in MnO₂ Cathode Material by Structural Engineering for Stable Cycling in Aqueous Zn Batteries

MnO2 is a promising cathode for aqueous Zn batteries. However, the cycling stability is seriously hindered by active material dissolution, and the pre-addition of Mn2+ salts in electrolytes is widely required. Herein, we propose a structural engineering strategy for MnO2 to enhance the capacity contribution from the reversible two-electron transfer reaction of MnO2/Mn2+ and realize stable cycling in Mn2+-free electrolytes. By compositing with MoO3, MnO2 exhibits weakened Mn–O bonds, more oxygen vacancies, spontaneous generation of structural water, and thus a lowered energy barrier for Mn release during discharge. Meanwhile, the composite material presents stronger electrostatic attractions for dissolved Mn2+, which ensures highly reversible re-deposition during charge. As a result, the mass ratios between materials undergoing reversible two-electron and one-electron transfer reactions increase from 0.85 in MnO2 to 1.68 in the MnO2/MoO3 composite material. In the ZnSO4 electrolyte, the MnO2/MoO3 cathode achieves 92.6% capacity retention after 300 cycles at 0.1 A g–1 (>1900 h), superior to 62.7% for MnO2. MnO2/MoO3 also retains 80.1% capacity after 16 000 cycles at 1 A g–1 (>3200 h). This work presents an effective path to realize stable cycling of MnO2 in Zn batteries