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Brett Robinson - One of the best experts on this subject based on the ideXlab platform.
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Biowastes to augment the essential oil production of Leptospermum scoparium and Kunzea robusta in low-fertility soil.
Plant physiology and biochemistry : PPB, 2019Co-Authors: S. Seyedalikhani, Jacqui Horswell, Nicholas M. Dickinson, J. Esperschuetz, R. Hofmann, J. Breitmeyer, Brett RobinsonAbstract:Abstract Biowastes are unwanted materials of biological origin. They include biosolids, dairy shed effluent, and sawdust. When applied to soil, biowastes can provide plant nutrients, but also introduce heavy metals, pathogens, or xenobiotics. Biowastes could improve degraded or low-fertility soils and generate revenue through the production of non-food products such as essential oils. We grew New Zealand native plants, mānuka (Leptospermum scoparium J.R. Forst & G. Forst) and kānuka (Kunzea robusta de Lange & Toelken) in series of greenhouse experiments in low-to-medium-fertility soils (Bideford clay loam, Lismore stony silt loam, and Pawson silt loam) amended with either biosolids (up to 13500 kg N ha−1 equiv.), biosolids + sawdust (1:0.5–1250 kg N ha−1 equiv.) and dairy shed effluent (200 kg N ha−1 equiv.). Two types of biosolids from Kaikoura (KB) and Christchurch City Council (CB) were used in the experiments. CB (1500 kg N ha−1 equiv.) and dairy shed effluent (200 kg N ha−1 equiv.) increased the biomass of L. scoparium by up to 120% and 31%, and K. robusta by up to 170% and 34%, respectively. Adding sawdust to KB increased the biomass of L. scoparium and K. robusta although it offset the L. scoparium growth increase in the KB-only treatment. The growth response of K. robusta to biowastes was greater than L. scoparium with oil production in K. robusta increasing by up to 211% when 1500 kg N ha−1 equiv. of CB was applied to Lismore stony silt loam. Generally, the treatments had a negligible effect on oil concentration in all the soil types, except for the KB + sawdust treatment, which increased the oil concentration by 82%. Most of the EOs’ major components were unaffected by biowaste addition in the soils, although some components increased in the Bideford clay loam following KB and KB + sawdust application. Biosolids increased foliar concentrations of Zn, Cu, and Cd, but these were below risk-threshold concentrations. Applying CB (up to 1500 kg N ha−1 equiv.) to low-fertility soils is recommended to establish ecosystems dominated by L. scoparium and K. robusta that annually would produce ca. 100 kg ha−1 of EOs worth US$ 26k and 24k, respectively. Adding sawdust to CB could have environmental benefits through reduction of N leaching. Field trials are warranted to elucidate critical ecological variables and production economics in biowaste management.
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Response of a Pioneering Species (Leptospermum scoparium J.R.Forst. & G.Forst.) to Heterogeneity in a Low-Fertility Soil
Frontiers in Plant Science, 2019Co-Authors: Maria Jesus Gutiérrez-ginés, Engracia Madejón, Niklas J. Lehto, Roger D. Mclenaghen, Jacqui Horswell, Nicholas M. Dickinson, Brett RobinsonAbstract:Root foraging may increase plant nutrient acquisition at the cost of reducing the total volume of soil explored, thereby reducing the chance of the roots encountering additional patches. Patches in soil seldom contain just one nutrient: the patch may also have distinct textural, hydrological, and toxicological characteristics. We sought to determine the characteristics of root foraging by a pioneering species, Leptospermum scoparium, using pot trials and rhizobox experiments with patches of biosolids. The growth of L. scoparium was increased by
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response of a pioneering species Leptospermum scoparium j r forst g forst to heterogeneity in a low fertility soil
Frontiers in Plant Science, 2019Co-Authors: Maria Jesus Gutierrezgines, Engracia Madejón, Niklas J. Lehto, Roger D. Mclenaghen, Jacqui Horswell, Nicholas M. Dickinson, Brett RobinsonAbstract:Root foraging may increase plant nutrient acquisition at the cost of reducing the total volume of soil explored, thereby reducing the chance of the roots encountering additional patches. Patches in soil seldom contain just one nutrient: the patch may also have distinct textural, hydrological, and toxicological characteristics. We sought to determine the characteristics of root foraging by a pioneering species, Leptospermum scoparium, using pot trials and rhizobox experiments with patches of biosolids. The growth of L. scoparium was increased by <50 t/ha equiv. of biosolids but higher doses were inhibitory. Roots foraged patches of biosolids in a low-fertility soil. There was no evidence of chemotaxis, rather, the roots proliferated toward the patch of biosolids, following chemical gradients of nitrate. While the biosolids also contained high concentrations of other nutrients (P, K, and S), only significant chemical gradients of nitrate were found. Once the roots encountered a patch of biosolids, the growth of the plant increased to a level similar to plants growing in soil homogeneously mixed with biosolids or surface-applied biosolids. Our results indicate that roots forage nitrate, which is mobile in soil, and that gradients of nitrate may lead to patches containing other less mobile nutrients, such as phosphate or potassium.
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Mānuka (Leptospermum scoparium) roots forage biosolids in low fertility soil
Environmental and Experimental Botany, 2017Co-Authors: Flavia V.p. Reis, Maria Jesus Gutiérrez-ginés, Niklas J. Lehto, Carol Smith, Brett RobinsonAbstract:Abstract Potentially, biosolids could be applied to low fertility or degraded soils to establish mānuka (Leptospermum scoparium), an economically important plant species used for honey and essential oil production. Given that this pioneering species is adapted to low-fertility soils, it is unclear whether it would respond positively to biosolids. We aimed to determine the growth, root morphology and elemental uptake of L. scoparium in contrasting soils amended with biosolids, distributed either homogeneously or heterogeneously. Pot and rhizobox experiments revealed that the roots of L. scoparium morphologically foraged patches of biosolids in soil. This finding is in contrast to previous reports that foraging is uncommon in plants adapted to low fertility soils. In a low-fertility sand, biosolids increased the growth 40-fold, irrespective of the distribution of biosolids. This increase was lower (60%) in an orthic brown soil. In the biosolids-amended soils, the foliar concentrations of N, P, K, S, Mg and Ca were above 2%, 1.5 g kg−1, 0.8%, 2.0 g kg−1, 1.7 mg kg−1 and 0.8% respectively, which is within the range of concentrations found in native species in their natural habitat. In the control soils, foliar concentrations of N, P & S were significantly lower, indicating that these elements may be limiting. The maximum concentration of Mn (660 mg kg−1), Zn (211 mg kg−1), and Cd (1.5 mg kg−1) in leaves of plants growing in biosolids-amended soil should not cause concern to plant health, but it should be taken into account for their potential effect on trophic networks. Further experiments should focus on the design of field-scale applications of biosolids for improving L. scoparium growth and determine the effect of biosolids distribution on nutrient losses.
Jonathan M. Stephens - One of the best experts on this subject based on the ideXlab platform.
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Proteomic analysis of honey. Identification of unique peptide markers for authentication of NZ mānuka (Leptospermum scoparium) honey.
Food chemistry, 2020Co-Authors: Jessie Bong, Kerry M. Loomes, Martin Middleditch, Jonathan M. StephensAbstract:Abstract Proteomics is an emerging tool in food authentication that has not been optimised for honey analysis. In this study, we present a qualitative proteomic analysis of New Zealand mānuka (Leptospermum scoparium) honey. A total of fifty bee-derived proteins were identified in the honey, the most predominant being major royal jelly proteins (MRJPs). We also demonstrate for the first time the presence of unique nectar-derived proteins in mānuka honey. A total of 17 mānuka plant proteins were identified, a-third of which were putative pathogenesis-related proteins. Two proteins involved in drought tolerance were also identified. Twelve candidate peptides were selected as potential authentication markers based on their uniqueness to mānuka honey. Nectar analyses confirmed the origin and specificity of these peptides to L. scoparium nectar, thus presenting peptide profiling as a viable and novel approach for mānuka honey authentication. Raw data are available via ProteomeXchange with identifier PXD021730.
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Soil influences on plant growth, floral density and nectar yield in three cultivars of mānuka (Leptospermum scoparium)
New Zealand Journal of Botany, 2016Co-Authors: Elizabeth M. Nickless, Christopher Anderson, Georgie Hamilton, Jonathan M. Stephens, Jason J. WargentAbstract:ABSTRACTHoney derived from the nectar of Leptospermum scoparium J.R. et G. Forst. Myrtaceae (mānuka) is a high-value product and there is considerable potential for economic growth in honey-growing regions of New Zealand through increased nectar yield from mānuka plantations. Leptospermum scoparium exhibits a significant amount of phenotypic plasticity throughout regions in New Zealand where it has established, although the influences on this plasticity are unknown. When assessing L. scoparium as a nectar source for honey in marginal land areas, the possible effect of soil on nectar chemistry and yield should be considered. We investigated whether phenological patterns of flowering, plant growth, nectar composition and nectar yield were influenced by soil composition.Three different cultivars of L. scoparium were grown on 10 different soils in glasshouse conditions. The soils chosen were representative of the range of New Zealand soils where mānuka is being considered as a commercial crop for the honey in...
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Isolation, Structural Elucidation, and Synthesis of Lepteridine From Ma̅nuka (Leptospermum scoparium) Honey.
Journal of agricultural and food chemistry, 2016Co-Authors: Benjamin J. Daniels, Jonathan M. Stephens, Gordana Prijic, Sarah Meidinger, Kerry M. Loomes, Ralf C. Schlothauer, Daniel P. Furkert, Margaret A. BrimbleAbstract:Manuka honey, made from the nectar of Leptospermum scoparium, has garnered scientific and economical interest due to its nonperoxide antibacterial activity. Biomarkers for genuine manuka honey are increasingly in demand due to the presence of counterfeit manuka honey. This work reports the identification of a compound previously unreported in manuka honey by HPLC, and determination of the structure of the as 3,6,7-trimethyllumazine using NMR, MS, IR, and UV/vis spectroscopy. This assignment was confirmed by total synthesis. The natural product, renamed lepteridine, was only observed in manuka honeys and could potentially serve as a biomarker for genuine manuka honey.
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isolation structural elucidation and synthesis of lepteridine from manuka Leptospermum scoparium honey
Journal of Agricultural and Food Chemistry, 2016Co-Authors: Benjamin J. Daniels, Jonathan M. Stephens, Gordana Prijic, Sarah Meidinger, Kerry M. Loomes, Ralf C. Schlothauer, Daniel P. Furkert, Margaret A. BrimbleAbstract:Manuka honey, made from the nectar of Leptospermum scoparium, has garnered scientific and economical interest due to its nonperoxide antibacterial activity. Biomarkers for genuine manuka honey are increasingly in demand due to the presence of counterfeit manuka honey. This work reports the identification of a compound previously unreported in manuka honey by HPLC, and determination of the structure of the as 3,6,7-trimethyllumazine using NMR, MS, IR, and UV/vis spectroscopy. This assignment was confirmed by total synthesis. The natural product, renamed lepteridine, was only observed in manuka honeys and could potentially serve as a biomarker for genuine manuka honey.
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Soil influences on plant growth, floral density and nectar yield in three cultivars of mānuka (Leptospermum scoparium)
2016Co-Authors: Elizabeth M. Nickless, Georgie Hamilton, Jonathan M. Stephens, Christopher W.n. Anderson, Jason J. WargentAbstract:Honey derived from the nectar of Leptospermum scoparium J.R. et G. Forst. Myrtaceae (mānuka) is a high-value product and there is considerable potential for economic growth in honey-growing regions of New Zealand through increased nectar yield from mānuka plantations. Leptospermum scoparium exhibits a significant amount of phenotypic plasticity throughout regions in New Zealand where it has established, although the influences on this plasticity are unknown. When assessing L. scoparium as a nectar source for honey in marginal land areas, the possible effect of soil on nectar chemistry and yield should be considered. We investigated whether phenological patterns of flowering, plant growth, nectar composition and nectar yield were influenced by soil composition. Three different cultivars of L. scoparium were grown on 10 different soils in glasshouse conditions. The soils chosen were representative of the range of New Zealand soils where mānuka is being considered as a commercial crop for the honey industry. ANOVA and general linear models revealed no significant effect of soils on nectar composition or production; however, significant but complex interactions between cultivars and soils influenced plant growth and flowering (P ≤ 0.05). Accordingly, the overall nectar yield was influenced by cultivar and soil interaction. Measured attributes of the soil such as cation exchange capacity, sulphate, iron, manganese, calcium and chloride were shown to influence the plant parameters assessed. Results allowed modelling of nectar potential against each soil type and established a mānuka soil index to determine the most appropriate soil for each cultivar. The results indicated that potential nectar yield increases will be dependent on cultivars being deployed according to the nature of the soil present. Furthermore, the mānuka cultivars displayed significantly greater growth in response to increased nutrients and some cultivars increased floral density, suggesting potential to improve nectar yield by greater plant growth using targeted fertilisation.
Michael J Clearwater - One of the best experts on this subject based on the ideXlab platform.
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floral nectar of wild mānuka Leptospermum scoparium varies more among plants than among sites
New Zealand Journal of Crop and Horticultural Science, 2019Co-Authors: Merilyn Manleyharris, Michael J ClearwaterAbstract:ABSTRACTUnderstanding of the genetic and environmental controls of floral nectar production by mānuka (Leptospermum scoparium J.R.Forst. et G.Forst.) and other species is limited by high levels of ...
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Influence of genotype, floral stage, and water stress on floral nectar yield and composition of mānuka (Leptospermum scoparium).
Annals of botany, 2018Co-Authors: Michael J Clearwater, Maria Revell, Stevie Noe, Merilyn Manley-harrisAbstract:Background and aims Floral nectar can be variable in composition, influencing pollinator behaviour and the composition of honey derived from it. The non-peroxide antibacterial activity of mānuka (Leptospermum scoparium, Myrtaceae) honey results from the chemical conversion of the triose sugar dihydroxyacetone (DHA), after DHA accumulates for an unknown reason in the nectar. This study examined variation in nectar DHA, glucose, fructose and sucrose content with floral stage of development, between mānuka genotypes with differing flower morphology, and in response to water stress. Methods Six mānuka genotypes were grown without nectar-feeding insects. Stages of flower development were defined, nectar was harvested and its composition was compared between stages and genotypes, and with floral morphology. Water stress was imposed and its effect on nectar composition was examined. Key results Nectar was present from soon after flower opening until the end of petal abscission, with the quantity of accumulated nectar sugars rising, then stabilizing or falling, indicating nectar secretion followed by reabsorption in some genotypes. The quantity of DHA, the ratio of DHA to other nectar sugars and the fructose to glucose ratio also varied with stage of development, indicating differences in rates of production and reabsorption between nectar components. Nectar composition and yield per flower also differed between genotypes, although neither was positively related to nectary area or stomatal density. Drying soil had no effect on nectar composition or yield, but variation in nectar yield was correlated with temperature prior to nectar sampling. Conclusions Mānuka nectar yield and composition are strongly influenced by plant genotype, flower age and the environment. There were clear stoichiometric relationships between glucose, fructose and sucrose per flower, but DHA per flower was only weakly correlated with the amount of other sugars, suggesting that accumulation of the triose sugar is indirectly coupled to secretion of the larger sugars by the nectary parenchyma.
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regional annual and individual variations in the dihydroxyacetone content of the nectar of manuka Leptospermum scoparium in new zealand
Journal of Agricultural and Food Chemistry, 2014Co-Authors: Simon Williams, Merilyn Manleyharris, Michael J Clearwater, Jessica King, Maria Revell, Megan R Balks, Franziska Janusch, Michael Kiefer, P M Brooks, Murray I. DawsonAbstract:A method was designed and validated for the analysis of dihydroxyacetone in the floral nectar of manuka (Leptospermum scoparium). The method was applied to samples collected from different regions of the North Island and the Nelson region of the upper South Island of New Zealand during the period 2009-2012 as well as to nectar samples from some Australian Leptospermum species. The ratio of dihydroxyacetone to total sugar (DHA/Tsugar) was classified as low ( 0.002 mg/mg). Inter- and intraregional variation were observed as well as interannual variation with variation from low to high classification occurring within one region and from low to moderate between years. Australian species also demonstrated elevated levels of dihydroxyacetone in the nectar. Some garden cultivars were shown to produce very high nectar DHA/Tsugar, and a survey of cultivars was undertaken; cultivars with single-flowered red or pink flowers were the most common producers of very high nectar DHA/Tsugar.
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Regional, annual, and individual variations in the dihydroxyacetone content of the nectar of ma̅nuka (Leptospermum scoparium) in New Zealand.
Journal of agricultural and food chemistry, 2014Co-Authors: Simon Williams, Michael J Clearwater, Merilyn Manley-harris, Jessica King, Maria Revell, Megan R Balks, Franziska Janusch, Michael Kiefer, Peter Brooks, Murray I. DawsonAbstract:A method was designed and validated for the analysis of dihydroxyacetone in the floral nectar of manuka (Leptospermum scoparium). The method was applied to samples collected from different regions of the North Island and the Nelson region of the upper South Island of New Zealand during the period 2009-2012 as well as to nectar samples from some Australian Leptospermum species. The ratio of dihydroxyacetone to total sugar (DHA/Tsugar) was classified as low ( 0.002 mg/mg). Inter- and intraregional variation were observed as well as interannual variation with variation from low to high classification occurring within one region and from low to moderate between years. Australian species also demonstrated elevated levels of dihydroxyacetone in the nectar. Some garden cultivars were shown to produce very high nectar DHA/Tsugar, and a survey of cultivars was undertaken; cultivars with single-flowered red or pink flowers were the most common producers of very high nectar DHA/Tsugar.
Jason J. Wargent - One of the best experts on this subject based on the ideXlab platform.
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Soil influences on plant growth, floral density and nectar yield in three cultivars of mānuka (Leptospermum scoparium)
New Zealand Journal of Botany, 2016Co-Authors: Elizabeth M. Nickless, Christopher Anderson, Georgie Hamilton, Jonathan M. Stephens, Jason J. WargentAbstract:ABSTRACTHoney derived from the nectar of Leptospermum scoparium J.R. et G. Forst. Myrtaceae (mānuka) is a high-value product and there is considerable potential for economic growth in honey-growing regions of New Zealand through increased nectar yield from mānuka plantations. Leptospermum scoparium exhibits a significant amount of phenotypic plasticity throughout regions in New Zealand where it has established, although the influences on this plasticity are unknown. When assessing L. scoparium as a nectar source for honey in marginal land areas, the possible effect of soil on nectar chemistry and yield should be considered. We investigated whether phenological patterns of flowering, plant growth, nectar composition and nectar yield were influenced by soil composition.Three different cultivars of L. scoparium were grown on 10 different soils in glasshouse conditions. The soils chosen were representative of the range of New Zealand soils where mānuka is being considered as a commercial crop for the honey in...
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Soil influences on plant growth, floral density and nectar yield in three cultivars of mānuka (Leptospermum scoparium)
2016Co-Authors: Elizabeth M. Nickless, Georgie Hamilton, Jonathan M. Stephens, Christopher W.n. Anderson, Jason J. WargentAbstract:Honey derived from the nectar of Leptospermum scoparium J.R. et G. Forst. Myrtaceae (mānuka) is a high-value product and there is considerable potential for economic growth in honey-growing regions of New Zealand through increased nectar yield from mānuka plantations. Leptospermum scoparium exhibits a significant amount of phenotypic plasticity throughout regions in New Zealand where it has established, although the influences on this plasticity are unknown. When assessing L. scoparium as a nectar source for honey in marginal land areas, the possible effect of soil on nectar chemistry and yield should be considered. We investigated whether phenological patterns of flowering, plant growth, nectar composition and nectar yield were influenced by soil composition. Three different cultivars of L. scoparium were grown on 10 different soils in glasshouse conditions. The soils chosen were representative of the range of New Zealand soils where mānuka is being considered as a commercial crop for the honey industry. ANOVA and general linear models revealed no significant effect of soils on nectar composition or production; however, significant but complex interactions between cultivars and soils influenced plant growth and flowering (P ≤ 0.05). Accordingly, the overall nectar yield was influenced by cultivar and soil interaction. Measured attributes of the soil such as cation exchange capacity, sulphate, iron, manganese, calcium and chloride were shown to influence the plant parameters assessed. Results allowed modelling of nectar potential against each soil type and established a mānuka soil index to determine the most appropriate soil for each cultivar. The results indicated that potential nectar yield increases will be dependent on cultivars being deployed according to the nature of the soil present. Furthermore, the mānuka cultivars displayed significantly greater growth in response to increased nutrients and some cultivars increased floral density, suggesting potential to improve nectar yield by greater plant growth using targeted fertilisation.
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Analytical method development using FTIR-ATR and FT-Raman spectroscopy to assay fructose, sucrose, glucose and dihydroxyacetone, in Leptospermum scoparium nectar
Vibrational Spectroscopy, 2016Co-Authors: Elizabeth M. Nickless, Georgie Hamilton, Keith C. Gordon, Stephen E. Holroyd, Jason J. WargentAbstract:Abstract The carbohydrate dihydroxyacteone (DHA) occurs in significant levels in Leptospermum scoparium (mānuka) nectar and is the precursor of methylglyoxyl (MGO), the unique non-peroxide antibacterial activity (NPA) component in mānuka honey. The nectar of ten different cultivars of L. scoparium was assayed quantitatively for fructose, glucose, sucrose, and DHA with high pressure liquid chromatography (HPLC) for comparison with FT-Raman and FTIR-ATR spectroscopic methods. FT-Raman spectroscopy and ATR-FTIR spectroscopy, alongside chemometric methods using principal component analysis (PCA) and partial least squares (PLS) prediction were shown to be useful techniques to quantify and compare the nectar composition in a range of cultivars of L. scoparium .
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analytical ft raman spectroscopy to chemotype Leptospermum scoparium and generate predictive models for screening for dihydroxyacetone levels in floral nectar
Journal of Raman Spectroscopy, 2014Co-Authors: Elizabeth M. Nickless, Jonathan M. Stephens, Keith C. Gordon, Stephen E. Holroyd, Jason J. WargentAbstract:Leptospermum scoparium (Mānuka) is the source of nectar for Unique Mānuka Factor (UMF) honey. The chemical component of interest to this study is dihydroxyacetone (DHA). DHA is the precursor for the chemical methylglyoxyl which is the main chemical responsiblefortheUMFactivityinManukahoney.ScreeningcommerciallybredplantsforincreasedDHAsynthesisinL. scoparium is a critical factor in growing the Manuka Honey industry in New Zealand. FT-Raman spectroscopy, in combination with principal component analysis and partial least squares regression analysis, was investigated as an analytical tool for building a screening model for DHA in the nectar of L. scoparium. Leaf samples of seven cultivars of the species L. scoparium were collected in an attempt to correlate metabolic factors in the plant with DHA synthesis in the nectar. Leaf material was analysed using Fourier transform-ramanspectroscopy (FT-Raman). The DHA levels in nectarsamples of the samecultivars were measured using standard LC-MS methods. This study showed that the application of multivariate analysis of FT-Raman spectra from leaf material is a useful tool to screen for DHA potential inL. scoparium. The PLS regression shows that we can screen for DHA concentrations in the range of 3300–7600mg/kg plus or minus 20% standard error and can distinguish low medium and high DHA synthesis in the group of plants studied. The model for predicting DHA concentrations is influenced by a significant contribution from the spectral variance due to beta-carotene and other highly scattering compounds that are not directly correlated with UMF. Copyright © 2014 John Wiley & Sons, Ltd. Additional supporting information may be found in the online version of this article at the publisher’s web site.
Merilyn Manley-harris - One of the best experts on this subject based on the ideXlab platform.
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Influence of genotype, floral stage, and water stress on floral nectar yield and composition of mānuka (Leptospermum scoparium).
Annals of botany, 2018Co-Authors: Michael J Clearwater, Maria Revell, Stevie Noe, Merilyn Manley-harrisAbstract:Background and aims Floral nectar can be variable in composition, influencing pollinator behaviour and the composition of honey derived from it. The non-peroxide antibacterial activity of mānuka (Leptospermum scoparium, Myrtaceae) honey results from the chemical conversion of the triose sugar dihydroxyacetone (DHA), after DHA accumulates for an unknown reason in the nectar. This study examined variation in nectar DHA, glucose, fructose and sucrose content with floral stage of development, between mānuka genotypes with differing flower morphology, and in response to water stress. Methods Six mānuka genotypes were grown without nectar-feeding insects. Stages of flower development were defined, nectar was harvested and its composition was compared between stages and genotypes, and with floral morphology. Water stress was imposed and its effect on nectar composition was examined. Key results Nectar was present from soon after flower opening until the end of petal abscission, with the quantity of accumulated nectar sugars rising, then stabilizing or falling, indicating nectar secretion followed by reabsorption in some genotypes. The quantity of DHA, the ratio of DHA to other nectar sugars and the fructose to glucose ratio also varied with stage of development, indicating differences in rates of production and reabsorption between nectar components. Nectar composition and yield per flower also differed between genotypes, although neither was positively related to nectary area or stomatal density. Drying soil had no effect on nectar composition or yield, but variation in nectar yield was correlated with temperature prior to nectar sampling. Conclusions Mānuka nectar yield and composition are strongly influenced by plant genotype, flower age and the environment. There were clear stoichiometric relationships between glucose, fructose and sucrose per flower, but DHA per flower was only weakly correlated with the amount of other sugars, suggesting that accumulation of the triose sugar is indirectly coupled to secretion of the larger sugars by the nectary parenchyma.
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Regional, annual, and individual variations in the dihydroxyacetone content of the nectar of ma̅nuka (Leptospermum scoparium) in New Zealand.
Journal of agricultural and food chemistry, 2014Co-Authors: Simon Williams, Michael J Clearwater, Merilyn Manley-harris, Jessica King, Maria Revell, Megan R Balks, Franziska Janusch, Michael Kiefer, Peter Brooks, Murray I. DawsonAbstract:A method was designed and validated for the analysis of dihydroxyacetone in the floral nectar of manuka (Leptospermum scoparium). The method was applied to samples collected from different regions of the North Island and the Nelson region of the upper South Island of New Zealand during the period 2009-2012 as well as to nectar samples from some Australian Leptospermum species. The ratio of dihydroxyacetone to total sugar (DHA/Tsugar) was classified as low ( 0.002 mg/mg). Inter- and intraregional variation were observed as well as interannual variation with variation from low to high classification occurring within one region and from low to moderate between years. Australian species also demonstrated elevated levels of dihydroxyacetone in the nectar. Some garden cultivars were shown to produce very high nectar DHA/Tsugar, and a survey of cultivars was undertaken; cultivars with single-flowered red or pink flowers were the most common producers of very high nectar DHA/Tsugar.
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Analysis of the flavonoid component of bioactive New Zealand mānuka (Leptospermum scoparium) honey and the isolation, characterisation and synthesis of an unusual pyrrole.
Food chemistry, 2013Co-Authors: Ching Wan Chan, Alistair L. Wilkins, Benjamin J. Deadman, Merilyn Manley-harris, Dagmar G. Alber, Elizabeth J. HarryAbstract:The flavonoid components of New Zealand mānuka (Leptospermum scoparium) honey have been quantified in a series of 31 honeys of varying non-peroxide antibacterial activity to clarify discrepancies between previous studies reported in the literature. Total flavonoid content was 1.16 mg/100 g honey. The principal flavonoids present were pinobanksin, pinocembrin, luteolin and chrysin and together these represented 61% of the total flavonoid content. 1, 2-formyl-5-(2-methoxyphenyl)-pyrrole, which was weakly correlated with the non-peroxide antibacterial activity, was isolated from the flavonoid fraction and separately synthesised. 1 did not display inhibitory activity against Staphylococcus aureus in vitro and thus the origin of the correlation, which is still unknown, is not a direct contribution.