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Item The Leptospermum scoparium (Mānuka)-Specific Nectar and Honey Compound 3,6,7-Trimethyllumazine (LepteridineTM) That Inhibits Matrix Metalloproteinase 9 (MMP-9) Activity(MDPI (Basel, Switzerland), 2023-11-09) Lin B; Nair S; Fellner DMJ; Nasef NA; Singh H; Negron L; Goldstone DC; Brimble MA; Gerrard JA; Domigan L; Evans JC; Stephens JM; Merry TL; Loomes KM3,6,7-trimethyllumazine (Lepteridine™) is a newly discovered natural pteridine derivative unique to Mānuka (Leptospermum scoparium) nectar and honey, with no previously reported biological activity. Pteridine derivative-based medicines, such as methotrexate, are used to treat auto-immune and inflammatory diseases, and Mānuka honey reportedly possesses anti-inflammatory properties and is used topically as a wound dressing. MMP-9 is a potential candidate protein target as it is upregulated in recalcitrant wounds and intestinal inflammation. Using gelatin zymography, 40 μg/mL LepteridineTM inhibited the gelatinase activities of both pro- (22%, p < 0.0001) and activated (59%, p < 0.01) MMP-9 forms. By comparison, LepteridineTM exerted modest (~10%) inhibition against a chromogenic peptide substrate and no effect against a fluorogenic peptide substrate. These findings suggest that LepteridineTM may not interact within the catalytic domain of MMP-9 and exerts a negligible effect on the active site hydrolysis of small soluble peptide substrates. Instead, the findings implicate fibronectin II domain interactions by LepteridineTM which impair gelatinase activity, possibly through perturbed tethering of MMP-9 to the gelatin matrix. Molecular modelling analyses were equivocal over interactions at the S1' pocket versus the fibronectin II domain, while molecular dynamic calculations indicated rapid exchange kinetics. No significant degradation of synthetic or natural LepteridineTM in Mānuka honey occurred during simulated gastrointestinal digestion. MMP-9 regulates skin and gastrointestinal inflammatory responses and extracellular matrix remodelling. These results potentially implicate LepteridineTM bioactivity in Mānuka honey's reported beneficial effects on wound healing via topical application and anti-inflammatory actions in gastrointestinal disorder models via oral consumption.Item Characterization of mānuka and rosemary oils as antimicrobial and antioxidant agents for meat applications : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North, New Zealand(Massey University, 2023) Kaur, RamandeepThe usage of chemical preservatives in meat products has been associated with adverse health effects, which is driving consumers' preferences towards natural preservatives. Raw and processed meats have been linked to cancers due to the presence of nitrate/nitrite as a chemical preservative. In recent years, extensive innovative and promising approaches have been exploited to entirely or partially replace synthetic preservatives. Plant-based natural preservatives possessing antioxidant and antimicrobial characteristics can be ideal for food applications. Essential oils are aromatic liquids extracted from different plant parts, such as leaves, bark, roots, and seeds, and are rich sources of bioactive compounds like monoterpenes, sesquiterpenes, and oxygenated sesquiterpenes and phenolic compounds. As per the literature, essential oils possessing antioxidant and antimicrobial characteristics have been reported to decline the rate of oxidative reactions and microbial growth. This study aims to harness the potential of essential oil obtained from the indigenous plant of New Zealand, i.e., mānuka, as a natural antioxidant and antimicrobial agent for meat preservation than chemical preservatives like nitrates/nitrites. As per the available literature, β-triketones are responsible for the antimicrobial characteristics of mānuka oil. We hypothesise that using antioxidants and antimicrobial bioactive compounds of Leptospermum scoparium (mānuka) will improve the shelf life and stability of the meat products. The first research objective characterised and compared the antioxidant and antimicrobial potential of mānuka oil with different triketone contents (5, 25, and 40 %) and kānuka oil with a commonly used natural preservative, i.e., rosemary oil. In chemical composition, kānuka oil possessed higher levels of α-pinene, while rosemary oil exhibited higher amounts of 1,8 cineole and α-pinene as primary compounds. In mānuka oils, the concentration of other compounds decreased as triketone content increased from 5 to 40 %. A comparison of the antioxidant characteristics of these oils was also made with chemical antioxidants, i.e., butylated hydroxytoluene (BHT). It was observed that mānuka oils possess higher antioxidant properties than rosemary and BHT (at both the lowest tested concentrations of 0.1 % and 1 %). In the antimicrobial efficacies assay results, all mānuka oils showed more effectiveness against Listeria monocytogenes and Staphylococcus aureus than Salmonella and Escherichia coli. However, the inhibition effect of rosemary oil was greater against Salmonella and Escherichia coli than mānuka oil (Chapter 3). The minimum inhibitory concentration of all mānuka oils required to inhibit Listeria monocytogenes and Staphylococcus aureus was below 0.04 %, while kānuka and rosemary oil inhibited these microbes at 0.63 and 2.5 %, respectively. On the other hand, a minimum 2.5 % concentration of all oils was needed to inhibit Salmonella and Escherichia coli. These results indicated that mānuka oil can be used as an antimicrobial agent, particularly against tested Gram-positive microbes (at a very concentration of 0.04 %) in meat products, while rosemary oil can be used against all tested microbes at 2.5 %. However, meat constituents such as fats have a significant effect on the efficacies of added bioactive compounds, therefore, it is essential to have insights into the lipophilicity of added essential oils and their bioactive compounds. In the next research experiment, to confirm the lipophilic behaviour of chemical compounds present in mānuka oil, the octanol-water partition coefficient of beta-triketones (leptospermone, isoleptospermone, and flavesone), α-pinene and γ-terpinene were elucidated using shake flask method (Gas chromatography and mass spectrometry) and predicted using EPI software (Chapter 4). High values of the octanol-water partition coefficient of these compounds indicate their more affinity towards the fat than the water. Further, when the concentration of the compounds separated in 3 and 12 % beef-fat and water systems was determined, all compounds showed higher concentrations in water of the low-fat system than in the high-fat. The findings pointed out that essential oils may exert an antioxidant effect in the high-fat system to prevent lipid oxidation; however, their antimicrobial effect may be reduced due to the presence of fat, and higher concentrations of these oils may be needed to achieve an antimicrobial effect against selected microbes. In the third research experiment, selected mānuka and rosemary oils were used as natural antioxidants and antimicrobial agents in low and high-fat meat pastes prepared from commercial-breed and wagyu beef tenderloins, respectively (Chapter 5). These effects were compared against the chemical preservative sodium nitrate and butylated hydroxytoluene during refrigerated storage of meat pastes at 4 °C. In commercial and wagyu beef pastes, a lower number of Listeria monocytogenes and Staphylococcus aureus were observed in mānuka and rosemary oil treatments than in the sodium nitrate and control samples (without added preservative). Rosemary oil also delayed the growth of Salmonella and Escherichia coli more than mānuka oil added and control samples. In terms of oxidative stability, mānuka oil added wagyu beef pastes were more stable and showed the lowest lipid oxidation values than all treatments. In commercial beef samples, no significant difference between essential oils added samples, either mānuka or rosemary oil and control samples was observed. There was a significant change in pH values of all wagyu and commercial beef samples, whilst these changes were greater in untreated samples (controls) than in the essential oils-treated samples. Despite the promising antioxidant and antimicrobial characteristics of essential oils, these are rarely utilised in food products owing to their easy degradation, low water solubility, low stability, and unwanted odour and flavour. The application of essential oils in encapsulated form is an effective and innovative approach to overcome these limitations by covering the core materials (oil droplets) in carrier materials. In addition, it improves stability and provides controlled release and targeted delivery of essential oils in foods. In the next research objective, mānuka and rosemary oils-containing nonentities (nanoemulsions and nanocapsules) made of sodium alginate and whey protein were fabricated and compared for their thermal stability and release characteristics (Chapter 6). The particle size and zeta potential of prepared nanoentities were between 100 -600 nm and -10 to -40 mV, confirming that the obtained nanoemulsions and nanocapsules were stable and in the nano range. The obtained nanoentities were observed to be more thermostable, sustained release profile than the free form of oils while showing a lower in vitro antioxidant effect. The release mechanism of the essential oil from nanoemulsions and nanocapsules was also studied using different mathematical models. The release mechanism of essential oil from nanoemulsions and nanocapsules followed Higuchi’s law, which indicates that the solvent first penetrates the encapsulated matrix and then dissolves the embedded oil droplets through the diffusion process. The delayed or sustained release from encapsulated oil might influence the antioxidant and antimicrobial activity of essential oils in meat pastes. However, a food matrix made up of different constituents can affect the partitioning and release of essential oils from the carrier material, and consequently, their preservative effect may vary according to the meat paste. An improvement in the antioxidant activity of oils after emulsification was observed as nanoemulsions of both oils had the lowest TABRS values in crossbred and wagyu pastes (Chapter 7). Mānuka oil and its nanoentities had more antioxidant effects than rosemary oil. In wagyu pastes, there was a significant difference in nanoemulsions added pastes than the other treatments, while in crossbred pastes, no significant differences were noted between free oils and nanoentities containing beef pastes. Despite the antioxidant efficacies, the antimicrobial activity of free, nanoemuslfisied and nanoencapsulated oils was also determined in the wagyu and crossbred beef pastes during refrigerated storage (4 °C) of two weeks. These antimicrobial effects were compared against controls (without added preservatives) and sodium nitrite-added paste samples. There was a significant increase in microbial counts of all inoculated-paste samples, whilst this increase was lower in preservatives added samples than in the controls. In wagyu and crossbred beef pastes, mānuka oil and its nanoentities delayed the growth of Listeria monocytogenes and Staphylococcus aureus, and mānuka-nanoemulsions exhibited the lowest number of these microbes than all other treatments. However, rosemary oil and its nanoforms effectively inhibited Salmonella and Escherichia coli during refrigerated storage at 4 °C. To better understand the mechanism for the antimicrobial activity of essential oils against selected pathogens, cell viability membrane integrity and the release of intracellular compounds and proteins through fluorescence-based assays were determined. In all these assay results, mānuka and rosemary oils treatment of Listeria monocytogenes, Staphylococcus aureus, Salmonella and Escherichia coli exhibited a decline in cell viability, disrupted cell-wall permeability and enhanced release of intracellular compounds and proteins from cells than the untreated cells. Scanning electron micrographs also confirmed that these mechanisms were responsible for the antibacterial efficacy of mānuka and rosemary oil. To correlate the effect of fat content on varied antimicrobial characteristics of essential oils in meat pastes, the partitioning of essential oils in different phases, such as octanol, beef and water, was determined. Overall, the work showed that mānuka oil has the potential to be used in meat pastes as an antimicrobial agent, especially against tested Gram-positive (Listeria monocytogenes and Staphylococcus aureus). In addition, this oil can be used to completely replace synthetic antioxidants like butylated hydroxytoluene to inhibit lipid oxidation in high-fat meat systems. Due to the lipophilic nature of oils, the fat content of meat systems significantly affects the partitioning of these oils in water and fat phases, which in turn affect their antimicrobial efficacies.Item The role of microorganisms in shaping the nectar chemistry of mānuka plants (Leptospermum scoparium) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology at Massey University, Manawatū, New Zealand(Massey University, 2022) Bresciano Kauffman, Jorge CarloMānuka (Leptospermum scoparium) honey is one of the main export products from New Zealand. The distinctiveness of this honey comes from the floral nectar, which possesses dihydroxyacetone, a carbohydrate with UV protection capabilities, which converts to methylglyoxal, usually during the honey maturation process. Methylglyoxal gives mānuka honey its biological activity (antimicrobial and antioxidant properties) and is often used as a quality marker. While it is acknowledged that microorganisms play an important role in plant ecology, their abundance and impact on nectar chemistry remain understudied. Microorganisms can arrive in the nectar by pollinator activity or through the phloem and can change nectar chemical properties. This thesis aims to fill a gap in the knowledge of the microbial diversity of the nectar; the impact of pollinators in the microbial nectar community, and the effect of bacteria on dihydroxyacetone production and sugar content in mānuka nectar. To achieve this aim, a combination of metagenomics, bacterial cultivation, chemical analyses, and biological in vivo and in vitro assays was conducted. The results show that mānuka nectar bacterial communities were dominated by Pseudomonadales, followed by Rhizobiales, Sphingomonadales, Corynebacteriales, Baccillales, Enterobacteriales, Xanthomonadales, Clostridiales, and Lactobacillales, while nectar fungi communities were dominated by Microbotryomycetes, Dothideomycetes, Malasseziomycetes, Sordariomycetes, and Ustilaginomycetes. When comparing bagged (pollinator restricted) and unbagged (with pollinator access) flowers, a bioinformatic and statistical analysis showed the bacterial community did not differ in community composition. In contrast, the fungal community was affected by pollinator visitation, and by plant genotype. The inoculation of an important functional bacterial Pantoea agglomerans, that previously was identified as a biomarker for the bacterial community, determined by linear discriminant analysis and network analysis, showed a significant increase in DHA using natural nectar under the laboratory. However, P. agglomerans in vivo inoculation did not change the composition of the main nectar sugars, suggesting that bacterial inoculation can maximize important plant metabolites like DHA, with minor disruption to nectar sugar content. The cultivable bacterial community differed little from the main groups found through metabarcoding, meaning the stability or structure of a core bacterial community in the nectar can be maintained through cultivation. This thesis fills an important gap in the knowledge of microbial ecology of mānuka plants and provides insights into how to manipulate key bacteria to increase DHA nectar content.Item Volatile organic compounds emitted by invasive and native plant species under invasion scenarios and their potential ecological roles : a thesis presented in partial fulfilment of the requirement for the degree of Doctor of Philosophy in Ecology at Massey University, Palmerston North, New Zealand(Massey University, 2020) Effah, EvansClimate change, human migration, and global trade favour the spread of plant species beyond their natural ranges. Many of these plants become invasive, posing a risk to the persistence and survival of native species and the ecosystems they invade. In New Zealand, the European woody shrub Calluna vulgaris (heather) is the most widespread invasive weed on the Central Plateau of North Island. Like most exotic invasive plants, the chemical behaviour (i.e. chemical production and chemical mediated interactions) of heather in its invaded habitat is poorly understood. Moreover, despite the struggles of native plants to endure the stress induced by exotic weeds, no study has documented the chemical behaviour of native plant species in plant invasion scenarios. Volatile organic compounds (VOCs) are secondary plant metabolites that play a vital role in plant communication with other organisms and are highly responsive to biotic and abiotic stress. Therefore, measuring VOC emissions during plant invasion could provide valuable information about plant responses to the changing environment and their potential impacts on other community members. This thesis aimed to investigate VOCs emitted by the invasive weed heather and a New Zealand native plant Leptospermum scoparium (mānuka) under field conditions, while determining the environmental factors regulating their emissions and exploring their potential ecological impacts under lab and field conditions. Results from the field trials on the Central North Plateau showed variations in the volatile profiles of heather and mānuka growing at different sites, with both plants emitting lower amounts of VOCs at sites where other exotic invasive plants were present. This reduction in VOC emissions was mostly due to indirect changes in environmental factors, like soil properties, which were driven by the invasive weeds heather and Cytisus scoparius (Scotch broom; henceforth broom). This thesis also documents the chemical responses of heather to two major stresses encountered in New Zealand; 1) elevated solar ultraviolet radiation (UV) and 2) damage caused by its introduced specialist herbivore and biocontrol agent Lochmaea suturalis (heather beetle). Results from these trials demonstrate that high UV radiation reduced the volatile emissions of some compounds (mainly terpenoids) and that the impacts of herbivory by heather beetle on VOC emission depended on the developmental stage of the herbivore, plant phenology, and season. The ability of VOCs emitted from heather and broom to affect the germination and growth of mānuka was also tested in the lab, while the impact on arthropod communities were investigated at sites on the Central North Plateau. The results suggest that VOCs produced by invasive plants may have phytotoxic effects toward mānuka and may alter arthropod community structure. This thesis highlights the complexity of plant chemical communication under invasion scenarios and invites further exploration of the interactions between exotic invasive plants and native species to broaden our understanding of invasion ecology to support weed management, biocontrol, and conservation efforts.Item Environmental and genetic influences on growth, flowering, and nectar production in mānuka (Leptospermum scoparium J.R. Forst. & G. Forst.) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science, School of Agriculture and Environment, Massey University, Palmerston North, New Zealand(Massey University, 2019) Sheridan, Rachael ElizabethDihydroxyacetone (DHA) in floral nectar of the Mānuka shrub, Leptospermum scoparium (J.R. & G. Forst.) is a direct precursor to methylglyoxal (MGO) the bioactive compound of manuka honey. Accumulation of DHA in Mānuka nectars varies between trees, localities, and years. However, the reasons for this variability are largely unknown and its origins in nectar are unclear. Since high DHA to total sugar ratios (DHA/TSugar) in fresh honey result in high MGO in mature honey, it follows that nectars with high DHA/TSugar will produce high-value honey indicated by a high Unique Mānuka Factor (UMF®) attracting premium returns for the NZ honey industry and NZ economy. It is key to further optimise both nectar and DHA production by selecting for high producers. Selecting/developing varieties for maximum nectar potential (NP) needs an understanding of the relative influences of genotype (G), environment (E), and their interactions (GEI) on relevant trait expression. The responses of genetic clones from three high yielding Mānuka lines expressing varying levels of nectar DHA to temperature, light, and soil moisture were studied in controlled environments. The relative performances of the clones were evaluated and contributions of G, E, and GEI to aspects of their growth, flowering and nectar production quantified.--Shortened abstractItem Influential factors in nectar composition and yield in Leptospermum scoparium : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science, Institute of Agriculture and the Environment, College of Sciences, Massey University, Palmerston North, New Zealand(Massey University, 2015) Nickless, Elizabeth MaryLeptospermum scoparium (Mānuka) is the plant nectar source for medically bioactive honey, commercially marketed in New Zealand as Unique Mānuka Factor honey (UMF-honey). Methylglyoxal (MGO) is the unique bioactive component of UMF honey with Mānuka nectar containing significant amounts of the carbohydrate dihydroxyacetone (DHA), the chemical precursor for MGO. Anecdotal evidence and recently published data from nectar samples collected from various cultivars in natural sites or botanical gardens has indicated that the DHA and overall composition of L. scoparium nectar varies according to cultivar. The source of this variation is not clearly understood and although there is considerable literature on climatic and genetic influences on nectar composition and yield within various other plant species, there is little published work available on the influence of genetic and environmental factors on the composition and yield of nectar in L. scoparium. Of value to the commercial UMF honey industry in New Zealand is the ability to assess cultivars from breeding programs for the best potential to increase overall UMF honey yield. Predictive modelling of yields is invaluable to the developing honey industry to allow assessment of environmental influences that may affect overall yield along with seasonal influences on nectar production in Mānuka. The research in this thesis establishes the effect of various parameters on overall DHA yield from Mānuka and the beginnings of modelling influencing environmental factors. To determine influences on dihydroxyacetone (DHA) concentration and yield in the nectar of L. scoparium a number of studies were carried out. Methodologies for the collection and analysis of nectar were established. Ten different cultivars of L. scoparium with a range of genetic parentage were studied in controlled glasshouse conditions to assess phenotypic variability in terms of nectar composition and yield as well as plant growth and flowering amongst these cultivars. Significant differences in plant growth and flowering habits were observed amongst the ten cultivars, significant differences in nectar yield and nectar composition with regard to DHA yield were also observed. DHA yields ranged from 2714-7459 mg of DHA/kilogram normalised to 80 oBRIX, with total nectar sugar yields ranging between 0.7 and 4.8 mg amongst the ten cultivars studied. Preliminary research into the effect of temperature, radiation and humidity on nectar composition and yield were also undertaken. Effects of soil composition on these same parameters were researched with a subset of three of the ten cultivars grown on ten different soil types. Plant relative growth rates, dry weights and total plant height were measured throughout a 15 month glasshouse trial. Plant growth, flowering phenology, floral density, nectar yield and DHA composition data was gathered. Soils were analysed for various macronutrient and micronutrient levels and these parameters were modelled against plant data to determine which soil components were influencing plant parameters of interest. Soil type was shown to have no significant effect on DHA concentrations in nectar but results did show that soil type had a significant effect on flowering density amongst the three L. scoparium cultivars studied in the trial. Results from regression analysis of soil chemistry against measured plant parameters indicate that a fertiliser regime has the potential to increase nectar yields due to increased flower numbers. Multivariate analysis using partial least squares regression of soil composition data against plant parameters of value showed that soil components; phosphorus, sulphate, ferric and chloride were commonly shown to influence plant parameters measured. Analytical spectroscopy was investigated as a method to chemotype L. scoparium cultivars and also as a method for quantifying nectar components sucrose, glucose, fructose and DHA. Nectar composition was analysed using high pressure liquid chromatography (HPLC) and compared with fourier transform Raman spectroscopy (FT-Raman) and attenuated total reflectance infrared spectroscopy (ATR-FTIR) analytical spectroscopy methods. FT-Raman spectroscopy was shown to be useful in chemotyping cultivars and in addition proved to be a useful analytical method to predict DHA yield using leaf material from L. scoparium plants from the ten cultivars. FT-Raman and ATR-FTIR proved to be relatively accurate techniques to quantify L. scoparium nectar components DHA, fructose, glucose and sucrose, compared with HPLC methods which use extensive preparation techniques. R-squared values were very good for all nectar components measured excepting the sucrose model at R2 = 0.77. The R2 for the FT-Raman predictions of DHA against HPLC data are very good at 0.85. FTIR prediction data against HPLC data was also good at 0.86 R2. Overall an accurate model is possible for quantifying DHA concentrations in nectar using both FTIR-ATR and FT-Raman spectroscopy. Overall results show that various factors need to be considered when assessing plants for commercial use in the (UMF) Mānuka honey industry within New Zealand. Due to their large impact on overall nectar yield; floral density and plant growth rate parameters are the two key factors of value for commercial assessment of Mānuka cultivars. This research also highlights the importance of assessing not just DHA concentration in deducing cultivar value, but overall nectar yield. These key features must be explored when assessing L. scoparium plants within breeding programs, prior to selection for large-scale field production of high UMF Mānuka honey.Item Ecological trends in the wood anatomy of Leptospermum scoparium J.R. et G. Forst (Manuka) family, Myrtaceae : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Science in Plant Biology at Massey University(Massey University, 2000) Lebutswe, TebogoThe wood anatomy of manuka growing in five different habitats was analysed to establish whether or not different anatomical forms exist. The study involved the use of the light microscope for obtaining vessel and fibre quantitative data such as their length, width, wall thickness, density of vessel elements in a transection and average grouping of vessels. The confocal microscope was used to measure the area of perforation plates of fibriform vessels and wide vessels. The study also involved the use of the scanning electron microscope for determining the presence of cell wall sculpturing in the walls of wide vessels. The data was analysed by univariate analysis to determine any variation of wood characters within a population and between populations in the five habitats. The habitats were margins of lowland forests, swamp, sand dune, subalpine and hot thermal soils. The study has established variations within each population in all the cell types. The study showed that plants differed anatomically in the average sizes of their cell length, width, wall thickness, abundance of vessels, area of perforation plates and the average grouping and the type of grouping of vessels. There was also variation of wood anatomy between populations in most cell characters except for the length of wide vessels, length of fibriform vessels and wall thickness of fibre-tracheids. In these characters the wood anatomy of manuka was more homogeneous. The significant trends were that margins of lowland forests had wide and thick walled cells in all the cell types and also had high average group of vessels and large area of perforation plates of fibriform vessels and small area of perforation plates for wide vessels. It had short libriform fibres and fibre-tracheids. The swamp habitat seemed to follow margins of lowland forests except that it had the longest fibre-tracheids and libriform fibres and had the greatest area of perforation plates for wide vessels. Both of these habitats had the lowest density of wide vessels. Sand dune, hot thermal soils and subalpine habitats had on average the smallest vessels in terms of diameter and wall thickness and area of perforation plates, but had high abundance or density of wide vessels. Sand dune had wide and thick walled libriform fibres like margins of lowland forests. Subalpine and hot thermal soils had comparatively small fibres in all dimensions. Even though variations were established in most of the cell characters, the correlation of wood with ecology was less pronounced as compared to that found in families and genera in past research. Significant trends were manifest in diameter, wall thickness and density of wide vessels. The margins of lowland forests and swamp (more mesic habitats) had great diameter and cell wall thickness. They also had low density of cells. The other habitats, sand dune, subalpine and hot thermal soils (less mesic habitats) had comparatively narrow diameter of wide vessels, thin cell walls and high levels of wide vessels densities. It was found that the other characters such as length, width, wall thickness of fibriform vessels, libriform fibres, and fibre-tracheids, grouping and area of perforation plates of wide vessels showed complex and overlapping ranges between the habitats and had no significant correlation with ecology. From this research it is clear that general trends of ecological adaptation were evident and also that manuka has its own specific ecological trends.Item Manuka (Leptospermum scoparium) as a remediation species for biosolids amended land : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Soil Science at Massey University, Manawatu, New Zealand(Massey University, 2011) Prosser, Jennifer AnnThe application of biowastes such as biosolids to land is a viable means of recycling valuable nutrients in an otherwise useless waste product. With this practice comes the risk of introducing contaminants such as heavy metals and pathogenic microorganisms into the soil system, posing a risk to humans and animals. A landmanagement system is needed to mitigate any potential risk. One such system finding application at many locations around the world is phytoremediation, the use of plants to remove, degrade or render harmless environmental contaminants. The plant species Leptospermum scoparium (Manuka) is a hardy native New Zealand plant resistant to heavy metals, with the ability to grow on degraded and erosion prone sites, and encourage re-vegetation in zones of impaired soil quality. In addition, manuka products have been shown to have antiseptic and antimicrobial properties. The aim of this research was to investigate the potential use of manuka in the remediation of contaminated land, through the use of manuka’s antiseptic properties to aid in pathogen control, and on the extraction or stabilisation of heavy metals in soil. Experiments were carried out using water extracts of manuka, as well as soil from underneath manuka stands, to test for antimicrobial activity of manuka against a number of pathogenic bacteria potentially found in biosolids. Results found that the presence of prepared manuka-water extracts significantly reduced the growth of the five bacterial strains tested, in some cases exhibiting complete die off. However, in-situ effects of antimicrobial ability in soil from underneath manuka were not observed. Further research using whole plants, and different plant components would be useful. Research was also conducted to investigate the effect of manuka growth on Zn and Cu bioavailability in soil. Three plant species, (manuka, Coprosma robusta and rye grass), were grown for six months and one year in Zn - and Cu - spiked soil to assess their effect on metal availability. Results clearly showed that the three plant species investigated differ in their ability to uptake and accumulate both metals, but have no apparent effect on HM bioavailbility over a one year time period. The experiments in this research were able to closely evaluate the potential of manuka as a remediation species for biosolids-amended land. Results indicate that further research into the potential use of manuka in this way is warranted, particularly with respect to manuka’s ability to manage levels of pathogenic soil microorganisms. In addition, manuka components are economically valuable, and in future, biosolids disposal systems may be able to combine with that of manuka production to produce a sustainable disposal system with potential for economic return. The solution may be to develop manuka plantations on otherwise unuseable land, where biosolids application can help recondition soil and enhance manuka growth, whilst manuka acts as a means of ‘treating’ both the bacterial and inorganic contaminants in the biosolids. Continual leaf fall or rotational cropping and mulching of manuka biomass would aid in the attenuation of introduced bacteria, and manuka roots may help stabilise metals. In an age where waste reduction and contaminant control are top priority, remediation systems such as this may represent an economically, socially and environmentally acceptable solution.