Neonectria ditissima is the fungal cause of costly European Canker (EC) in apple trees. A range of secondary metabolites were found at higher concentrations in infected twigs than in disease free twigs. Apple trees were then experimentally inoculated with N. ditissima and analyzed periodically until EC symptoms were visible at 12-13 weeks post-inoculation. Established destructive detection methods used were microscopy, which showed extensive hyphal penetration by 8 weeks post inoculation, and qPCR analyses, which confirmed the presence of N. ditissima. Headspace solid-phase microextraction GC-MS data showed significantly higher concentrations of styrene in apple twigs at six weeks after inoculation, and LC-MS data showed phloretin, triterpene acids, and 1-benzoyl β-d-glucose at raised concentrations after this time. Therefore, these compounds could be useful indicators of N. ditissima infection prior to visible canker formation, suitable for nondestructive disease detection development after further research on apple variety, pathogen specificity, and on field detection technology.

The potential of cannabinoids to address public health challenges has stimulated exploration into alternative sources and production technologies. Radula marginata, an endemic Aotearoa/New Zealand liverwort, produces the bibenzyl cannabinoid perrottetinene (PET), analogous to Cannabis psychoactive tetrahydrocannabinol (THC). Structural differences between PET and THC could alter therapeutic interactions and mitigate adverse side effects. To understand the cannabinoid production potential of R. marginata, we analyzed 75 collections from three locations across several seasons, collaborating with kaitiaki M & amacr;ori (indigenous guardians). Metabolic plasticity of the phytocannabinoids and plant growth was assessed under controlled growth conditions, and in in vitro culture. Perrottetinene diol (trans-PTD), analogous to cannabidiol (trans-CBD), and its acid precursor (PTDA), were identified and fully characterized from nature for the first time. Bibenzyl-4-geranyl (BB4G), analogous to cannabigerol (CBG), and its corresponding acid (BB4GA), were also isolated. Radula marginata showed chemotypes dominated by PET, PTD, or BB4G, in striking analogy to the main Cannabis chemotypes. These site-selective chemotypes persisted after growth under artificial lighting and in in vitro progeny, suggesting genetic control. These results expand phytocannabinoid knowledge through the discovery of PTD analogous to CBD. They add a new dimension to liverwort cannabinoids and suggest convergent evolution of biosynthesis in two distant plant lineages.

Butein, a rare chalcone found in the toxic plant Toxicodendron vernicifluum, has been shown to regulate glucose homeostasis via inhibition of the nuclear factor kappa-B kinase subunit beta (IKKβ)/nuclear factor kappa B (NF-κB) pathway in the brain. Here, we investigated whether the nonpoisonous plant Dahlia pinnata could be a source of butein as a potential treatment for type 2 diabetes (T2D). In mice fed a high-fat diet (HFD) to induce glucose intolerance, an oral D. pinnata petal extract improved glucose tolerance at doses of 3.3 mg/kg body weight and 10 mg/kg body weight. Surprisingly, this effect was not mediated by butein alone but by butein combined with the closely related flavonoids, sulfuretin and/or isoliquiritigenin. Mechanistically, the extract improved systemic insulin tolerance. Inhibition of phosphatidylinositol 3-kinase to block insulin signaling in the brain abrogated the glucoregulatory effect of the orally administered extract. The extract reinstated central insulin signaling and normalized astrogliosis in the hypothalamus of HFD-fed mice. Using NF-κB reporter zebrafish to determine IKKβ/NF-κB activity, a potent anti-inflammatory action of the extract was found. A randomized controlled crossover clinical trial on participants with prediabetes or T2D confirmed the safety and efficacy of the extract in humans. In conclusion, we identified an extract from the flower petals of D. pinnata as a novel treatment option for T2D, potentially targeting the central regulation of glucose homeostasis as a root cause of the disease.

The methyl-migrated bicyclic skeleton of the halimane diterpenes has been found in a wide range of organisms, including flowering plants, liverworts, marine animals, and bacteria. The discovery of halima-1(10),14-dien-13-ol (3) from the Aotearoa New Zealand endemic alpine daisy Celmisia viscosa is now reported. The full configuration was assigned for the first time by X-ray crystallography, enantiomeric to that of a liverwort isolate. The absolute configuration at C-5 of the halimane is opposite to that at C-5 of the labdane epimanool (1) found in some C. viscosa specimens. Two new 2,6-dideoxyhexopyran-3-uloside halimane derivatives (4 and 5) were also found, and the absolute configuration of 5 was determined by 1H NMR analysis of the Mosher esters. Line broadening in the 13C NMR spectra of these halim-1(10)-enes was due to conformational exchange in the decalin ring A, as shown by molecular modeling and DFT calculations. 1H NMR and GC analyses of leaf extracts of individual plants from across the full geographic range of C. viscosa revealed intraspecific variation of diterpenes: 37 samples had halimadienol as the main diterpene in large amounts and 2 specimens had predominantly epimanool, again in large amounts. Three other viscid (sticky leaved) Celmisia species also contained diterpenes, but none was detectable in four nonviscid Celmisia species.

Flavonoids acylated on their core phenolic groups are rare. The Aotearoa New Zealand endemic alpine daisy Celmisia viscosa is widespread, but its flavonoids have not previously been identified. Leaf extracts yielded a series of 8-O-acylated flavones with combinations of 3-methylbutanoate, 2-methylbutanoate, and 2-methylpropanoate groups and one, two, or three O-methyls, all previously unreported. Regiochemistries of 8-(3″-methylbutanoyl)-5-hydroxy-6,7,4'-trimethoxyflavone (5) and 8-(2″-methylbutanoyl)-5,7,4'-trihydroxy-6-methoxyflavone (10) were defined by X-ray crystallography. LC analyses of leaf extracts from the full geographic range of C. viscosa showed intraspecific variation of these flavones: most had high concentrations of trimethoxy 8-O-acylated flavones, but dimethoxy 8-O-acylated flavones were the most abundant flavonoids in two individuals. Three other viscid (sticky leaved) Celmisa species also contained these rare flavones, but four nonviscid Celmisa had none detectable.

Introduction Hydrogen is the most efficient and economical carrier gas for gas chromatography (GC). However, there are rare reports of artefact formation by hydrogenation of unsaturated compounds on GC. Head space solid-phase microextraction (HS-SPME) GC conditions for hydrogenation were studied. Methodology HS-SPME-GC-mass spectrometry (MS) analyses of common classes of plant volatiles were carried out using hydrogen (H-2) and helium (He) carrier gases with different SPME fibre coatings, GC inlet temperatures, and desorption times. Results Common phenylpropanoids, monoterpenes, and green leaf volatiles were hydrogenated to varying degrees on HS-SPME-GC with H-2 carrier gas and SPME fibres coated with polydimethylsiloxane (PDMS)/Carboxen (CAR), PDMS/divinylbenzene (DVB), and PDMS/CAR/DVB. No artefacts were detected using PDMS-only coated fibres or He carrier gas. Conclusion Unsaturated plant volatiles may be hydrogenated on HS-SPME-GC when using H-2 carrier gas with SPME fibre coatings containing DVB polymer or CAR porous particles. Parallel analyses with He and H-2 carrier gases are recommended when developing HS-SPME-GC methods for plant volatiles, or use of PDMS-only coated fibres.

2-O-β-d-Glucopyranosyl l-ascorbic acid (AA-2βG) is a stable, bioavailable vitamin C (AA) derivative. We report the distribution and seasonal variation of AA-2βG in apples and its occurrence in other domesticated crops and in wild harvested Ma̅ori foods. Liquid chromatography-mass spectrometry analyses showed high AA-2βG concentrations in crab apples (Malus sylvestris) but low concentrations in domesticated apples. Leaves of crab and domesticated apple cultivars contained similar intermediate AA-2βG concentrations. Fruits and leaves of other crops were analyzed: mainly Rosaceae but also Actinidiaceae and Ericaceae. AA-2βG was detected in all leaves (0.5-6.1 mg/100 g fr. wt.) but was at lower concentrations in most fruits (0.0-0.5 mg/100 g fr. wt.) except for crab apples (79.4 mg/100 g fr. wt.). Ma̅ori foods from Solanaceae, Piperaceae, Asteraceae, and a fern of Aspleniaceae also contained AA-2βG. This extensive occurrence suggests a general role in AA metabolism for AA-2βG.

The concentrations and pro-oxidative effects of free fatty acids in commercial krill oil are not well defined. We now report that krill oil free fatty acids account for 2–13% of total lipids in commercial krill oil (n = 8) that these compounds are enriched in eicosapentaenoic acid (+7.1%) and docosahexaenoic acid (+6.3%) relative to whole oils; and that this composition make them highly pro-oxidizing in marine triacylglycerol oils, but not in krill oil, which derives oxidative stability from both its phospholipids, and neutral lipids (the latter because of astaxanthin). Specific fatty acid esterification patterns showed that krill oil free fatty acids predominantly (88–93%) originated from phospholipids, mainly from the sn-2 position, which was eight-fold more hydrolyzed than the sn-1 position. Lipolysis was not ongoing in stored oils. Adding small amounts of krill oil (1–5%) to marine triacylglycerol oils significantly increased their oxidative stability and also their resistance to free fatty acid-mediated pro-oxidative effects.

Non-targeted LC-MS metabolomics on fruit of three wild and domesticated apple species (Malus sylvestris, M. sieversii and M. domestica) showed that two crab apple (M. sylvestris) accessions were distinguished by high concentrations of an ascorbic acid glycoside (AAG). This was partly purified, but key NMR signals were masked by inseparable sucrose. Reference samples of 2-O-β-D-glucopyranosyl L-ascorbic acid and 2-O-β-D-galactopyranosyl L-ascorbic acid were synthesised, but both coincided with the crab apple AAG on LC-MS. Peracetylation of the crab apple extract allowed both purification and characterisation, and the AAG was proven to be 2-O-β-D-glucopyranosyl L-ascorbic acid by comparison of 1H NMR, HRMS and HPLC data with synthesised peracetylated ascorbyl glycoside standards. The stability of the natural AA 2-β-glycoside was similar to synthetic 2-O-α-D-glucopyranosyl L-ascorbic acid, used widely in cosmetic and pharmaceutical products. This discovery in crab apples (Rosaceae) is only the fourth reported occurrence of any ascorbyl glycoside from plants, the others being from Cucurbitaceae, Solanaceae and Brassicaceae. It is hypothesised that AAGs may be more widespread in plants than currently realised.

ABSTRACT This special issue of New Zealand Journal of Crop & Horticultural Science includes papers describing some current research activities in mānuka. The research projects were planned and undertaken with various degree of Māori involvement. Here we give a perspective as three of the senior authors, and discuss science at the intersection of Māori and Pākehā cultures, focusing on mānuka. The underlying conclusion is that the processes for accessing plant material, engaging with Māori on the use of this material in science, and the ownership and dissemination of resulting data, have not often been appropriate and there should be a greater degree of inclusion of Māori in research involving taonga species. There is increasing recognition amongst non-Māori scientists within the Aotearoa New Zealand science community that research involving taonga species must follow the country’s founding document, the Treaty of Waitangi, and be led by Māori cultural values, concepts and practices. On this basis future research involving taonga species should include co-design and co-management of research projects, analysis of the risks and benefits, and prior discussion and agreement on the use and implications of any new knowledge generated.

ABSTRACT Knowledge about the behaviour of passive dispensers used to release semiochemicals for insect pest management is essential to ensure the efficacy of monitoring and control methods based on the use of the semiochemicals. The release characteristics of different passive dispenser types (commercial sachet, altered commercial sachet, polyethylene bags and cotton rolls) were investigated in the laboratory under various conditions. Using the volatile compound methyl isonicotinate (MI), a known lure for western flower thrips Frankliniella occidentalis (Pergande) and two additional homologues ethyl and n-propyl isonicotinate the effect of loading amount (0.5, 1.0 or 2.5 ml), temperatures (15°C, 25°C or 35°C) and air flow (0.1–0.15 m/s or 0.25–0.3 m/s) were tested in a low-speed laminar-flow wind tunnel. The results showed zero-order release kinetics for all tested dispenser types. Release rate kinetics relies on the type of molecule, dispenser type, and the climatic conditions with temperature being a major determinant of release rate. The results of the release characteristics of the different dispensers are discussed in regards to their practical use under greenhouse and field conditions.

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are commercially important omega-3 fatty acids found in fish oils. Here we demonstrate that a handheld Raman spectrometer can be used to quantitate these compounds in intact fish oil capsules, avoiding oxidizing risk. Partial least squares regression models were prepared by relating Raman spectral variance to EPA and DHA concentrations determined using gas chromatography–mass spectrometry (GC-MS) analysis of fatty acid methyl esters in 15 commercial samples containing 145–473 mg g−1 EPA and 101–260 mg·g−1 DHA. Handheld Fourier transform (FT)-Raman models had root mean square errors of cross-validation of 38 mg g−1, 24 mg g−1, and 32 mg·g−1 for EPA, DHA, and EPA+DHA, respectively. Models generated from a benchtop FT-Raman spectrometer had corresponding errors of 32 mg·g−1, 22 mg·g−1, and 26 mg·g−1. By comparison, average standard deviations from triplicate GC-MS analyses were 11 mg·g−1 for EPA and 9 mg·g−1 for DHA.

ABSTRACT Leptospermum scoparium J. R. et G. Forst. (Myrtaceae), called mānuka or kahikātoa by Māori, shows distinct foliage chemotypes in different regions of Aotearoa New Zealand, including one with rare antimicrobial triketones. To extend knowledge of mānuka chemotypes geographically and historically, we have developed a miniaturised method for analyses of herbarium samples needing just a few small leaves analysed by headspace solid phase microextraction gas chromatography (HS-SPME-GC). This method was validated on herbarium samples of known chemotypes. Geographical knowledge was extended by analysing herbarium samples collected on New Zealand's offshore islands, ranging from the Manawa/Three Kings in the North to Rakiura/Stewart Island in the South. The chemotypes were generally similar to the nearest populations on the main North or South islands. Historically, volatiles were identified from herbarium samples collected by the first botanists from Europe in 1769, showing that the oil glands in mānuka leaves act as ‘chemical time capsules’.

Kauri is an ecologically important and culturally treasured tree species in Aotearoa New Zealand. It is under threat from the pathogenic oomycete Phytophthora agathidicida, which causes kauri dieback disease. We hypothesised that matauranga Maori (Maori knowledge) of kauri forest health could be used to identify native plants that produce anti-Phytophthora compounds. We tested this hypothesis by using knowledge descended from Te Whare Wananga o Ngapuhi to select and screen four native plants for activity against P. agathidicida and also P. cinnamomi (a broad host-range pathogen). Extracts of kanuka (Kunzea robusta) were active against various life cycle stages. Bioassay-directed isolation led to three flavanones, previously unreported from New Zealand Kunzea, as the main bioactives. These compounds have not previously been reported as having anti-Phytophthora activities. They inhibited P. agathidicida zoospore germination with IC50 values of 1.4-6.5 mu g/mL, making them the most potent inhibitors reported against this stage of the life cycle. The three flavanones also inhibited zoospore motility at 2.5-5.0 mu g/mL, and showed some inhibition of mycelial growth at 100 mu g/mL. They were generally less active against P. cinnamomi. Overall, the results from this study emphasise the value of using matauranga Maori in the response to kauri dieback.

Strigolactones (SLs) are multifunctional plant hormones regulating essential physiological processes affecting growth and development. In vascular plants, SLs are recognized by α/β hydrolase-fold proteins from the D14/DAD2 (Dwarf14/Decreased Apical Dominance 2) family in the initial step of the signaling pathway. We have previously discovered that N-phenylanthranilic acid derivatives (e.g. tolfenamic acid) are potent antagonists of SL receptors, prompting us to design quinazolinone and quinazolinedione derivatives (QADs and QADDs, respectively) as second-generation antagonists. Initial in silico docking studies suggested that these compounds would bind to DAD2, the petunia SL receptor, with higher affinity than the first-generation compounds. However, only one of the QADs/QADDs tested in in vitro assays acted as a competitive antagonist of SL receptors, with reduced affinity and potency compared with its N-phenylanthranilic acid 'parent'. X-ray crystal structure analysis revealed that the binding mode of the active QADD inside DAD2's cavity was not that predicted in silico, highlighting a novel inhibition mechanism for SL receptors. Despite a ∼10-fold difference in potency in vitro, the QADD and tolfenamic acid had comparable activity in planta, suggesting that the QADD compensates for lower potency with increased bioavailability. Altogether, our results establish this QADD as a novel lead compound towards the development of potent and bioavailable antagonists of SL receptors.

We assembled the genome of Leptospermum scoparium 'Crimson Glory' using a combination of Illumina paired-end sequencing, high-throughput chromosome conformation capture (Hi-C) and high density genetic mapping. As 'Crimson Glory' is a variety of manuka, this is the first genome assembly for a plant species culturally recognised as a treasure (taonga) by the indigenous Maori of Aotearoa New Zealand. The manuka genome spans a total of 297 Mbp organised in 11 pseudo-chromosomes that are syntenic with the Eucalyptus genome. A large proportion of the genome assembly corresponds to fungal and bacterial sequences, indicating the presence of an associated microbiome. A total of 31,220 protein-coding gene models were detected throughout the genome, including genes involved in biosynthesis of biologically active phenylpropanoids, triketones and terpenes, as well as genes involved in biotic resistance. The manuka genome sequence will help shed new light on the genetic control of unique characters such as nectar and foliage biochemical composition, flowering time and disease resistance.

Chemotaxonomic analysis of kwhai leaf extracts in New Zealand are limited with previous reports of Sophora tetraptera having a flavonoid profile distinct from S. microphylla sensu lato and S. prostrata. Eight Sophora species are now recognised in New Zealand: S. chathamica, S. fulvida, S. godleyi, S. longicarinata, S. microphylla, S. molloyi, S. prostrata and S. tetraptera. We now report liquid chromatography-ultraviolet-mass spectrometry (LC-UV-MS) analyses of leaf and seed extracts of individual plants (2-16) from each of these eight species, plus the Chilean S. cassioides. All of the S. tetraptera leaf extracts had similar LC-UV-MS profiles, different from all of the other Sophora samples, consisting of four predominant compounds, characterised by MS and nuclear magnetic resonance (NMR) spectroscopy as: luteolin-7-O-rutinoside 1, luteolin-7-O-glucoside 2, apigenin-7-O-rutinoside 3, and apigenin-7-O-glucoside 4. The other Sophora leaf extracts showed complex flavonoid compositions, with no clear distinction between species. Most of the Sophora seed samples, including those of S. tetraptera, showed one major phenolic compound, but a few had a related compound. These were purified and characterised by MS and NMR spectroscopy as 3,4,7-trihydroxyisoflavone 5 (in most seeds) and its 7-O-glucoside 6 (in a few seeds), neither of which has been previously reported from these Sophora species.

Some honeys contain the neurotoxin tutin (1) plus hyenanchin (2), 2-(β-d-glucopyranosyl)tutin (3), and 2-[6'-(α-d-glucopyranosyl)-β-d-glucopyranosyl]tutin (4). These honeys are made by bees collecting honeydew from passionvine hoppers feeding on the sap of tutu plants ( Coriaria spp.). We report a LC-MS study showing that all these picrotoxanes are of plant, not insect, origin. Hyenanchin was barely detectable and the diglucoside was not detectable in C. arborea leaves, but tutu phloem sap contained all four compounds at concentrations up to the highest found in honeydew. It is proposed that the diglucoside may function as a transport form of tutin, analogous to sucrose transport in phloem.

The strigolactone (SL) family of plant hormones regulates a broad range of physiological processes affecting plant growth and development and also plays essential roles in controlling interactions with parasitic weeds and symbiotic fungi. Recent progress elucidating details of SL biosynthesis, signaling, and transport offers many opportunities for discovering new plant-growth regulators via chemical interference. Here, using high-throughput screening and downstream biochemical assays, we identified N-phenylanthranilic acid derivatives as potent inhibitors of the SL receptors from petunia (DAD2), rice (OsD14), and Arabidopsis (AtD14). Crystal structures of DAD2 and OsD14 in complex with inhibitors further provided detailed insights into the inhibition mechanism, and in silico modeling of 19 other plant strigolactone receptors suggested that these compounds are active across a large range of plant species. Altogether, these results provide chemical tools for investigating SL signaling and further define a framework for structure-based approaches to design and validate optimized inhibitors of SL receptors for specific plant targets.