ORCID Profile
0000-0001-8079-7774
Current Organisations
University of Surrey
,
Royal Botanic Gardens Kew
,
Agriculture and Agri-Food Canada
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Publisher: Elsevier BV
Date: 03-2020
DOI: 10.1016/J.FITOTE.2020.104478
Abstract: The sap of the tree Lepiniopsis ternatensis is used as a topical treatment for cutaneous leg ulcers in Papua New Guinea. This study, which is the first investigation of this medicinal plant, examines the effect of the sap on wound healing biology using human-derived primary cell lines. NMR spectra from 1D and 2D experiments revealed the sap to contain a single major component, identified as the polyphenol, trifucol. The sap significantly increased the proliferation of dermal fibroblasts at just 1.3 μg/ml, without influencing keratinocytes, suggesting a fibroblast-specific mechanism of stimulation. It also significantly inhibited TNF-α secretion by pro-inflammatory M1 macrophages, but not from neutrophils, at 130 μg/ml. The low toxicity of the sap towards dermal cells along with its fibroblast stimulation activity and downregulation of macrophage TNF-α makes it a potentially attractive agent to promote dermal wound healing in chronic non-healing ulcers.
Publisher: MDPI AG
Date: 16-04-2021
Abstract: Australia’s endemic desert shrubs are commonly aromatic, with chemically erse terpenes and phenylpropanoids in their headspace profiles. Species from the genus Eremophila (Scrophulariaceae ex. Myoporaceae) are the most common, with 215 recognised taxa and many more that have not yet been described, widely spread across the arid parts of the Australian continent. Over the years, our research team has collected multiple specimens as part of a survey to investigate the chemical ersity of the genus and create leads for further scientific enquiry. In the current study, the ersity of volatile compounds is studied using hydrodistilled essential oils and leaf solvent extracts from 30 taxa. Several rare terpenes and iridoids were detected in chemical profiles widely across the genus, and three previously undescribed sesquiterpenes were isolated and are assigned by 2D NMR—E-11(12)-dehydroisodendrolasin, Z-11-hydroxyisodendrolasin and 10-hydroxydihydro-α-humulene acetate. Multiple s ling from Eremophila longifolia, Eremophila arbuscular, Eremophila latrobei, Eremophila deserti, Eremophila sturtii, Eremophila oppositifolia and Eremophila alternifolia coneys that species in Eremophila are highly chemovariable. However, taxa are generally grouped according to the expression of (1) furanosesquiterpenes, (2) iridoids or oxides, (3) mixtures of 1 and 2, (4) phenylpropanoids, (5) non-furanoid terpenes, (6) mixtures of 4 and 5, and less commonly (7) mixtures of 1 and 5. Furthermore, GC–MS analysis of solvent-extracted leaves taken from cultivated specimens conveys that many heavier ‘volatiles’ with lower vapour pressure are not detected in hydrodistilled essential oils and have therefore been neglected in past chemical studies. Hence, our data reiterate that chemical studies of the genus Eremophila will continue to describe new metabolites and that taxon determination has limited predictive value for the chemical composition.
Publisher: Cold Spring Harbor Laboratory
Date: 08-03-2022
DOI: 10.1101/2022.03.07.483352
Abstract: We sequenced the genome of a global collection (40 isolates) of the fungus Pyrenophora tritici-repentis (Ptr), a major foliar pathogen of wheat and model for the evolution of necrotrophic pathogens. Ptr exhibited an open-pangenome, with 43% of genes in the core set and 57% defined as accessory (present in only a subset of isolates), of which 56% were singleton genes (present in only one isolate). A clear distinction between pathogenic and non-pathogenic genomes was observed in size, gene content, and phylogenetic relatedness. Chromosomal rearrangements and structural organization, specifically around the effector coding genes, were explored further using the annotated genomes of two isolates sequenced by PacBio RS II and Illumina HiSeq. The Ptr genome exhibited major chromosomal rearrangements, including chromosomal fusion, translocation, and segment duplications. An intraspecies translocation of ToxA , the necrosis-inducing effector-coding gene, was facilitated within Ptr via a 143 kb ‘ Starship’ transposon (dubbed ‘Horizon’). Additionally, ToxB , the gene encoding the chlorosis-inducing effector, was clustered as three copies on a 294 kb transposable element in a ToxB-producing isolate. ToxB and its carrying transposon were missing from the ToxB non-coding reference isolate, but the homolog toxb and the transposon were both present in another non-coding isolate. The Ptr genome also appears to exhibit a ‘one-compartment’ organization, but may still possess a ‘two-speed genome’ that is facilitated by copy-number variation as reported in other fungal pathosystems. Ptr is one of the most destructive wheat pathogens worldwide. Its genome is a mosaic of present and absent effectors, and serves as a model for examining the evolutionary processes behind the acquisition of virulence in necrotrophs and disease emergence. In this work, we took advantage of a erse collection of pathogenic Ptr isolates with different global origins and applied short- and long-read sequencing technologies to dissect the Ptr genome. This study provides comprehensive insights into the Ptr genome and highlights its structural organization as an open pangenome with ‘one-compartment’. In addition, we identified the potential involvement of transposable elements in genome expansion and the movement of virulence factors. The ability of effector-coding genes to shuffle across chromosomes on large transposons was illustrated by the intraspecies translocation of ToxA and the multi-copy ToxB . In terms of gene contents, the Ptr genome exhibits a large percentage of orphan genes, particularly in non-pathogenic or weakly-virulent isolates.
Publisher: Springer Science and Business Media LLC
Date: 24-10-2022
DOI: 10.1186/S12915-022-01433-W
Abstract: In fungal plant pathogens, genome rearrangements followed by selection pressure for adaptive traits have facilitated the co-evolutionary arms race between hosts and their pathogens. Pyrenophora tritici-repentis (Ptr) has emerged recently as a foliar pathogen of wheat worldwide and its populations consist of isolates that vary in their ability to produce combinations of different necrotrophic effectors. These effectors play vital roles in disease development. Here, we sequenced the genomes of a global collection (40 isolates) of Ptr to gain insights into its gene content and genome rearrangements. A comparative genome analysis revealed an open pangenome, with an abundance of accessory genes (~ 57%) reflecting Ptr’s adaptability. A clear distinction between pathogenic and non-pathogenic genomes was observed in size, gene content, and phylogenetic relatedness. Chromosomal rearrangements and structural organization, specifically around effector coding genes, were detailed using long-read assemblies (PacBio RS II) generated in this work in addition to previously assembled genomes. We also discovered the involvement of large mobile elements associated with Ptr’s effectors: ToxA , the gene encoding for the necrosis effector, was found as a single copy within a 143-kb ‘Starship’ transposon (dubbed ‘Horizon’) with a clearly defined target site and target site duplications. ‘Horizon’ was located on different chromosomes in different isolates, indicating mobility, and the previously described ToxhAT transposon (responsible for horizontal transfer of ToxA ) was nested within this newly identified Starship. Additionally, ToxB , the gene encoding the chlorosis effector, was clustered as three copies on a 294-kb element, which is likely a different putative ‘Starship’ (dubbed ‘Icarus’) in a ToxB-producing isolate. ToxB and its putative transposon were missing from the ToxB non-coding reference isolate, but the homolog toxb and ‘Icarus’ were both present in a different non-coding isolate. This suggests that ToxB may have been mobile at some point during the evolution of the Ptr genome which is contradictory to the current assumption of ToxB vertical inheritance. Finally, the genome architecture of Ptr was defined as ‘one-compartment’ based on calculated gene distances and evolutionary rates. These findings together reflect on the highly plastic nature of the Ptr genome which has likely helped to drive its worldwide adaptation and has illuminated the involvement of giant transposons in facilitating the evolution of virulence in Ptr.
Publisher: MDPI AG
Date: 13-11-2020
Abstract: The highly aromatic Australian mint bushes from the genus Prostanthera Labill. produce a high yield of essential oil on hydrodistillation. Together with its rich history, horticultural potential, iconic flowers, and aromatic leaves, it achieves high ornamental and culinary value. Species in the genus express highly erse and chemically unique essential oils that demonstrate intra- and inter-specific patterns that have inspired taxonomic reinterpretation for over a hundred years. Previous studies have conveyed that phenoplastic expression of volatiles creates chemotypes within taxa, adding complexity to chemophenetic exploration. The current study chemically characterised essential oils from 64 highly aromatic specimens, representative of 25 taxa, giving yields as high as % g/g. The chemical profiles of essential oils are erse, but generally include 1,8-cineole and signatory compounds such as sesquiterpene oxides, caryophyllene oxide, kessane and cis-dihydroagarofuran sesquiterpene alcohols, globulol, epiglobulol, maaliol, prostantherol, spathulenol and ledol and monoterpene derivatives of common scaffolds, borneol, bornyl acetate, bornanone, linalool and linalyl acetate. As in previous studies, analysis of chemical data confirms that the chemistry strongly agrees with taxonomic classifications. Importantly, as in classical taxonomy, the current chemical study complemented morphological analysis but conveys chemovariation, obscuring the taxonomic agreement. Nevertheless, variation within taxa may be due to environmental factors, meaning that cultivation of species in gardens will create different chemical profiles as compared to those published here.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Moses K. Langat.