Two aromatic acid derivatives and a xanthone from <i>Hypericum hengshanense</i>

Three previously undescribed compounds including two aromatic acid derivatives (1–2), and one xanthone (3), together with ten known compounds (4–13) were isolated from the aerial part of Hypericum hengshanense. The planar structures of three new compounds were established by 1 D and 2 D NMR and MS data. And the absolute configurations of compounds 1–2 were determined by the quantum chemical ECD calculations. Compounds 1–2 showed weak cytotoxicity against Hep-2 human cancer cell lines with IC50 values of 65.1 ± 2.7 and 78.0 ± 1.0 μg/mL, respectively.</p

Brand-New Method toward Widely Regulating Polymer Dispersity by Two-Dimensional Confining Radical Polymerization

Polymer dispersity (D̵) is a key parameter in polymer materials’ design and directly affects the properties and performances of the polymer. Numerous charming research studies based on the controlled/living polymerization have been carried out in this field, but the complicated initiation systems and specific experimental conditions are still inevitable. Here, we report a two-dimensional confining radical polymerization (TDCRP) through fluorinated graphene (FG) toward widely regulating the D̵ of vinyl polymers. Vinyl monomers attack the C–F bonds for initiating polymerization by the single-electron transfer reaction, showing the unique “region reaction” behavior. On account of the steric effect of the two-dimensional structure and the tunable interactions between the formed polymer segment and two-dimensional plane during the region reaction, the D̵ of vinyl polymers presents a time-dependent characteristic and is widely adjustable. Meanwhile, TDCRP also has the ability of tailoring D̵ from a wide range of vinyl monomers, which can be driven under different external fields including heat, light, and force. The changed surface morphology of the FG plane and polymerization temperature can further regulate the D̵ of the formed polymer. The versatile and robust nature of our strategy combined with the cutting-edge two-dimensional materials effectively regulates the radical polymerization, which may create an extensive interest among the polymer community and beyond

Tunable Bandgap in Silicene and Germanene

By using ab initio calculations, we predict that a vertical electric field is able to open a band gap in semimetallic single-layer buckled silicene and germanene. The sizes of the band gap in both silicene and germanene increase linearly with the electric field strength. Ab initio quantum transport simulation of a dual-gated silicene field effect transistor confirms that the vertical electric field opens a transport gap, and a significant switching effect by an applied gate voltage is also observed. Therefore, biased single-layer silicene and germanene can work effectively at room temperature as field effect transistors

Genome-Wide Mapping of Virulence in Brown Planthopper Identifies Loci That Break Down Host Plant Resistance

<div><p>Insects and plants have coexisted for over 350 million years and their interactions have affected ecosystems and agricultural practices worldwide. Variation in herbivorous insects' virulence to circumvent host resistance has been extensively documented. However, despite decades of investigation, the genetic foundations of virulence are currently unknown. The brown planthopper (<i>Nilaparvata lugens</i>) is the most destructive rice (<i>Oryza sativa</i>) pest in the world. The identification of the resistance gene <i>Bph1</i> and its introduction in commercial rice varieties prompted the emergence of a new virulent brown planthopper biotype that was able to break the resistance conferred by <i>Bph1.</i> In this study, we aimed to construct a high density linkage map for the brown planthopper and identify the loci responsible for its virulence in order to determine their genetic architecture. Based on genotyping data for hundreds of molecular markers in three mapping populations, we constructed the most comprehensive linkage map available for this species, covering 96.6% of its genome. Fifteen chromosomes were anchored with 124 gene-specific markers. Using genome-wide scanning and interval mapping, the <i>Qhp7</i> locus that governs preference for <i>Bph1</i> plants was mapped to a 0.1 cM region of chromosome 7. In addition, two major QTLs that govern the rate of insect growth on resistant rice plants were identified on chromosomes 5 (<i>Qgr5</i>) and 14 (<i>Qgr14</i>). This is the first study to successfully locate virulence in the genome of this important agricultural insect by marker-based genetic mapping. Our results show that the virulence which overcomes the resistance conferred by <i>Bph1</i> is controlled by a few major genes and that the components of virulence originate from independent genetic characters. The isolation of these loci will enable the elucidation of the molecular mechanisms underpinning the rice-brown planthopper interaction and facilitate the development of durable approaches for controlling this most destructive agricultural insect.</p></div

Host preferences and survival rates for Biotype 1 and 2 on TN1 and Mudgo rice plants.

<p>(A) and (B) The host preferences of Biotype 1 and 2 were assessed by recording the number of insects that settled on TN1 and Mudgo plants during 72h. Much more Biotype 1 insects chose the susceptible rice plants (TN1) than did resistant plants (Mudgo), while the Biotype 2 insects that settled on both rice plants exhibited similar number. (C) and (D) The survival rates of Biotype 1 and 2 insects were tested on TN1 and Mudgo plants by recording the number of nymphs. The Biotype 1 insects died much more individuals on resistant plants (Mudgo) than did on the susceptible rice plants after releasing 12 h, whereas the Biotype 2 insects survived well on both rice plants. *, Student's t-test, <i>P</i><0.05; **, Student's t-test, <i>P</i><0.01.</p

Overview of the consensus molecular linkage map for the brown planthopper.

a<p>LG, linkage group of consensus molecular linkage map;</p>b<p>G-SSR, the genomic SSR;</p><p>Jairin's map, the linkage groups according to a previous map <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098911#pone.0098911-Jairin1" target="_blank">[42]</a>.</p

Mapping of loci for growth rate among brown planthoppers on resistant rice plants.

<p>(A) Genome wide QTL scan for growth rate on the linkage map for the F₂ population. Two QTLs reached significant on chromosome 5 (34.1 cM) and 14 (14.5 cM), respectively. The horizontal bars represent 15 linkage groups. (B) Location and effect of the growth rate gene <i>Qgr5</i> on chromosome 5. It was located on a small region of chromosome 5 (between markers NLGS859 and NLGS13, their interval distance is 0.3 cM) and explained 17.8% of phenotypic variation from F₂ population. (C) Location and effect of the growth rate gene <i>Qgr14</i> on chromosome 14. It was located on a region of chromosome 14 (between markers NLGS72 and SRAP604-4, their interval distance is 1.1 cM) and explained 24.0% of phenotypic variation in F₂ population. The dashed horizontal line indicates the significant genome-wide threshold LOD scores (LOD = 4.5); the solid line indicates the significant linkage group-wide threshold LOD scores (LOD = 3.1 for chromosome 5 and LOD = 2.9 for chromosome 14).</p

The high density molecular linkage map for the brown planthopper (<i>N.lugens</i>).

<p>The molecular markers with different colors (black for EST-SSR; red for genomic SSR; green for SRAP markers) didn't evenly distribute across each of 15 linkage groups and the characteristics of this map are summarized in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098911#pone-0098911-t002" target="_blank">Table 2</a>. Markers whose names begin with NLES or NLGS are EST-SSRs or genomic SSRs from a previous map <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098911#pone.0098911-Jairin1" target="_blank">[42]</a>. Those whose names begin with BM or SRAP are microsatellite and SRAP markers developed in our laboratory. The anchoring EST-SSR markers are indicated in bold text and underlined; detailed information on these markers is presented in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098911#pone.0098911.s008" target="_blank">Table S8</a>. The number of these gene specific markers per chromosome ranged from 3 to 15, with an average of 8.</p

Quantitative trait loci identified for virulence traits in the F₁ and F₂ populations.

<p>LG: Linkage group for the F₁ or F₂ population; A: Additive effect; D: Dominance effect;</p><p>PVE: percentage of the phenotypic variance explained in mapping population;</p><p>a:The Genome-wide and Linkage-group-wide LOD thresholds are 4.9 and 3.5, respectively;</p><p>b:The Genome-wide and Linkage-group-wide LOD thresholds are 4.5 and 3.1, respectively;</p><p>c:The Genome-wide and Linkage-group-wide LOD thresholds are 4.5 and 2.9, respectively.</p

Oxford grids displaying a matrix of cells comparing the number of orthologous genes on chromosomes of <i>N. lugens</i> and selected model insects.

<p>(A) Much more orthologous genes were found between <i>Nilaparvata lugens</i> and <i>Nasonia vitripennis</i> comparison, indicating that a high syntenic relationship between these two insects. (B) and (C) The number of orthologous genes between <i>Nilaparvata lugens</i> and <i>Drosophila melanogaster</i> comparison and that of <i>Nilaparvata lugens</i> and <i>Tribolium castaneum</i> comparison were nearly same, indicating that their syntenic relationship with brown planthopper was similar.</p