A thrips vector of tomato spotted wilt virus responds to tomato acylsugar chemical diversity with reduced oviposition and virus inoculation.

There is increasing evidence that acylsugars deter insect pests and plant virus vectors, including the western flower thrips (WFT), Frankliniella occidentalis (Pergande), vector of tomato spotted wilt virus (TSWV). Acylsugars are sugar-polyesters composed of saturated, un-saturated, and variously branched short and long chain fatty acids (FAs) esterified to a glucose (acylglucose) or sucrose (acylsucrose) moiety. We sought to understand how acylsucrose amount and composition of associated FA profiles interacted to mediate resistance to WFT oviposition and TSWV inoculation on tomato leaves. Towards this goal, we examined WFT oviposition and TSWV inoculation behavior on tomato lines bred to exude varying amounts of acylsucrose in association with diverse FA profiles. Our data show that as acylsucrose amounts increased, WFT egg-laying (oviposition) decreased and TSWV inoculation was suppressed. Western flower thrips also responded to FA profiles that included iC4, iC11, nC12 and nC10 FA. These findings support improving acylsugar-mediated resistance against WFT by breeding tomatoes exuding greater amounts of acylsucrose associated with specific FA profiles. We show that increasing acylsucrose amount output by type IV trichomes and selecting for particular FA profiles through advanced breeding profoundly affects WFT behavior in ways that benefit management of WFT as direct pests and as TSWV vectors

Genome-enabled insights into the biology of thrips as crop pests

Background The western flower thrips, Frankliniella occidentalis (Pergande), is a globally invasive pest and plant virus vector on a wide array of food, fiber, and ornamental crops. The underlying genetic mechanisms of the processes governing thrips pest and vector biology, feeding behaviors, ecology, and insecticide resistance are largely unknown. To address this gap, we present the F. occidentalis draft genome assembly and official gene set. Results We report on the first genome sequence for any member of the insect order Thysanoptera. Benchmarking Universal Single-Copy Ortholog (BUSCO) assessments of the genome assembly (size = 415.8 Mb, scaffold N50 = 948.9 kb) revealed a relatively complete and well-annotated assembly in comparison to other insect genomes. The genome is unusually GC-rich (50%) compared to other insect genomes to date. The official gene set (OGS v1.0) contains 16,859 genes, of which ~ 10% were manually verified and corrected by our consortium. We focused on manual annotation, phylogenetic, and expression evidence analyses for gene sets centered on primary themes in the life histories and activities of plant-colonizing insects. Highlights include the following: (1) divergent clades and large expansions in genes associated with environmental sensing (chemosensory receptors) and detoxification (CYP4, CYP6, and CCE enzymes) of substances encountered in agricultural environments; (2) a comprehensive set of salivary gland genes supported by enriched expression; (3) apparent absence of members of the IMD innate immune defense pathway; and (4) developmental- and sex-specific expression analyses of genes associated with progression from larvae to adulthood through neometaboly, a distinct form of maturation differing from either incomplete or complete metamorphosis in the Insecta. Conclusions Analysis of the F. occidentalis genome offers insights into the polyphagous behavior of this insect pest that finds, colonizes, and survives on a widely diverse array of plants. The genomic resources presented here enable a more complete analysis of insect evolution and biology, providing a missing taxon for contemporary insect genomics-based analyses. Our study also offers a genomic benchmark for molecular and evolutionary investigations of other Thysanoptera species

Advances in heterometallic ring-opening (co)polymerisation catalysis

Truly sustainable plastics require renewable feedstocks coupled with efficient production and end-of-life degradation/recycling processes. Some of the most useful degradable materials are aliphatic polyesters, polycarbonates and polyamides, which are often prepared via ring-opening (co)polymerisation (RO(CO)P) using an organometallic catalyst. While there has been extensive research into ligand development, heterometallic cooperativity offers an equally promising yet underexplored strategy to improve catalyst performance, as heterometallic catalysts often exhibit significant activity and selectivity enhancements compared to their homometallic counterparts. This review describes advances in heterometallic RO(CO)P catalyst design, highlighting the overarching structure-activity trends and reactivity patterns to inform future catalyst design

Carbon dioxide utilisation in block polymers: catalysis and functional materials

The following thesis describes the synthesis of block polymers comprising polycarbonates (derived from carbon dioxide) and polyesters, and their evaluation as functional materials and possible renewable alternatives to current petrochemical-based plastics. The preparation of the polymers utilises efficient and sequence-controlled polymerisation catalysis, combining lactone ring-opening polymerisation (ROP) and epoxide/CO2 ring-opening copolymerisation (ROCOP) cycles through a single catalyst. Chapter 2 evaluates heterodinuclear zinc(II)/magnesium(II) catalysts for the switchable polymerisation catalysis of lactone and epoxide/CO2. The heterodinuclear catalyst, [LZnMg(OBzNMe2)2] where L = macrocyclic ancillary ligand, OBzNMe2 = parasubstituted benzoate, is initially assessed for the preparation of ABA-type triblock polymers, but because of poor end-group fidelity the development of a new organometallic catalyst, [LZnMg(C6F5)2] is undertaken. The organometallic catalyst shows strong performance with equivalent high activity for epoxide/CO2 ROCOP and enhanced activity for lactone ROP compared with the benzoate variant. Importantly, it delivers higher molar mass ABA triblock polymers (Mn > 20 kg mol-1 ) with block sequence-selectivity and with excellent end-group fidelity. Chapter 3 further explores the application of the organometallic Zn(II)/Mg(II) catalyst in switchable polymerisation catalysis. High molar mass ABA triblock polymers (38 n -1) with varying degrees of CO2 utilisation (6 – 23 wt %) are prepared by controlling the starting monomer stoichiometry, with the final materials comprising hard polycarbonate “A” blocks and a soft polyester “B” block. The effects of varying the relative block ratio on the thermal and mechanical characteristics of the polymers are analysed, and their performance as toughened plastics, elastomers, and pressure-sensitive adhesives is evaluated. Chapter 4 investigates the synthesis and thermal/mechanical effects of changing the polymer architecture by varying the initiating alcohol groups, from linear to stars. A range of tri-, tetra-, and hexafunctional star block polymers are synthesised from vinyl-cyclohexene oxide (vCHO), CO2, and ε-decalactone (ε-DL). It also investigates the selective postpolymerisation modification of the polycarbonate block at fixed relative block composition. Multi-arm star-like polymers are fashioned using a “core-first” approach by employing chaintransfer agents with varying numbers of hydroxyl groups. Trends in thermomechanical and morphological characteristics for both the non-modified and modified polymers are analysed in relation to molar mass (overall and individual arm) and number of star ‘arms’, and a preliminary assessment of particular advantages/disadvantages for star vs. linear architectures in these polymers is presented.</p

Block poly(carbonate-ester) ionomers as high-performance and recyclable thermoplastic elastomers

Thermoplastic elastomers based on polyesters/carbonates have the potential to maximize recyclability, degradability and renewable resource use. However, they often underperform and suffer from the familiar trade-off between strength and extensibility. Herein, we report well-defined reprocessable poly(ester-b-carbonateb- ester) elastomers with impressive tensile strengths (60 MPa), elasticity (>800%) and recovery (95%). Plus, the ester/carbonate linkages are fully degradable and enable chemical recycling. The superior performances are attributed to three features: (1) Highly entangled soft segments; (2) fully reversible strain-induced crystallization and (3) precisely placed Zn(II)-carboxylates dynamically crosslinking the hard domains. The one-pot synthesis couples controlled cyclic monomer ring-opening polymerization and alternating epoxide/anhydride ring-opening copolymerization. Easy conversion to ionomers is achieved using vinyl-substituted epoxides with phthalic anhydride

Switchable catalysis improves the properties of CO2-derived polymers: poly(cyclohexene carbonate-b-ε-decalactone-b-cyclohexene carbonate) adhesives, elastomers, and toughened plastics

Carbon dioxide/epoxide copolymerization is an efficient way to add value to waste CO2 and to reduce pollution in polymer manufacturing. Using this process to make low molar mass polycarbonate polyols is a commercially relevant route to new thermosets and polyurethanes. In contrast, high molar mass polycarbonates, produced from CO2, generally under-deliver in terms of properties, and one of the most widely investigated, poly(cyclohexene carbonate), is limited by its low elongation at break and high brittleness. Here, a new catalytic polymerization process is reported that selectively and efficiently yields degradable ABA-block polymers, incorporating 6–23 wt % CO2. The polymers are synthesized using a new, highly active organometallic heterodinuclear Zn(II)/Mg(II) catalyst applied in a one-pot procedure together with biobased ε-decalactone, cyclohexene oxide, and carbon dioxide to make a series of poly(cyclohexene carbonate-b-decalactone-b-cyclohexene carbonate) [PCHC-PDL-PCHC]. The process is highly selective (CO2 selectivity >99% of theoretical value), allows for high monomer conversions (>90%), and yields polymers with predictable compositions, molar mass (from 38–71 kg mol–1), and forms dihydroxyl telechelic chains. These new materials improve upon the properties of poly(cyclohexene carbonate) and, specifically, they show good thermal stability (Td,5 ∼ 280 °C), high toughness (112 MJ m–3), and very high elongation at break (>900%). Materials properties are improved by precisely controlling both the quantity and location of carbon dioxide in the polymer chain. Preliminary studies show that polymers are stable in aqueous environments at room temperature over months, but they are rapidly degraded upon gentle heating in an acidic environment (60 °C, toluene, p-toluene sulfonic acid). The process is likely generally applicable to many other lactones, lactides, anhydrides, epoxides, and heterocumulenes and sets the scene for a host of new applications for CO2-derived polymers