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Albert N.W.,Agresearch Ltd. | Albert N.W.,Plant and Food Research Ltd. | Griffiths A.G.,Agresearch Ltd. | Cousins G.R.,Agresearch Ltd. | And 2 more authors.
New Phytologist | Year: 2015

Summary: Anthocyanin pigments accumulate to form spatially restricted patterns in plants, particularly in flowers, but also occur in vegetative tissues. Spatially restricted anthocyanin leaf markings are poorly characterised in plants, but are common in forage legumes. We hypothesised that the molecular basis for anthocyanin leaf markings in Trifolium spp. is due to the activity of a family of R2R3-MYB genes. R2R3-MYB genes were identified that are associated with the two classic pigmentation loci in T. repens. The R locus patterns 'red leaf', 'red midrib' and 'red fleck' are conditioned by a single MYB gene, RED LEAF. The 'diffuse red leaf' trait is regulated by the RED LEAF DIFFUSE MYB gene. The V locus was identified through mapping two V-linked traits, 'V-broken yellow' (Vby) and 'red leaflet' (Vrl). Two highly similar R2R3-MYB genes, RED V-a and RED V-b, mapped to the V locus and co-segregated with the RED V pigmentation pattern. Functional characterisation of RED LEAF and RED V was performed, confirming their function as anthocyanin regulators and identifying a C-terminal region necessary for transactivation. The mechanisms responsible for generating anthocyanin leaf markings in T. repens provide a valuable system to compare with mechanisms that regulate complex floral pigmentation. © 2014 New Phytologist Trust. Source

Braakhuis A.J.,Sport Performance | Hopkins W.G.,Auckland University of Technology | Lowe T.E.,Plant and Food Research Ltd. | Rush E.C.,Auckland University of Technology
International Journal of Sport Nutrition and Exercise Metabolism | Year: 2011

A quantitative food-frequency questionnaire (FFQ) was developed to determine antioxidant intake in athletes. The questionnaire will be valuable for researchers wishing to standardize antioxidant intake or simply document habitual intake during an intervention trial. One hundred thirteen athletes participated in the validity study, of whom 96 completed the questionnaire and blood test, 81 completed the 7-d food diary and questionnaire, and 63 completed the 7-d food diary and blood test. Validity was investigated by comparing total and food-group antioxidant intakes from the questionnaire with those from a subsequent 7-d food diary. Measures of construct validity were determined by comparing a biomarker of antioxidant capacity (ferric-reducing ability of plasma) in a blood sample with antioxidant intakes from the questionnaire and diary. The correlation between the diary and questionnaire energy-adjusted estimates of total antioxidant intake was modest (.38; 90% confidence limits, ± .14); the correlation was highest for antioxidants from cereals (.55; ± .11), which contributed the greatest proportion (31%) of the total antioxidant intake. Correlations were also high for coffee and tea (.51; ± .15) and moderate for vegetables (.34; ± .16) and fruit (.31; ± .16). The correlation of the plasma biomarker with the questionnaire estimate was small (.28; ± .15), but the correlation with the diary estimate was inconsequential (-.03; ± .15). One-week test-retest reliability of the questionnaire's estimates of antioxidant intake in 20 participants was high (.83; ± .16). In conclusion, the FFQ is less labor intensive for participants and researchers than a 7-d diary and appears to be at least as trustworthy for estimating antioxidant intake. © 2011 Human Kinetics, Inc. Source

Rodado A.,Massey University | Bebbington M.,Massey University | Noble A.,Plant and Food Research Ltd. | Cronin S.,Massey University | Jolly G.,Institute of Geological & Nuclear Sciences
Mathematical Geosciences | Year: 2011

Estimating the occurrence probability of volcanic eruptions with VEI ≥3 is challenging in several aspects, including data scarcity. A suggested approach has been to use a simple model, where eruptions are assumed to follow a Poisson process, augmenting the data used to estimate the eruption onset rate with that from several analog volcanoes. In this model the eruption onset rate is a random variable that follows a gamma distribution, the parameters of which are estimated by an empirical Bayes analysis. The selection of analog volcanoes is an important step that needs to be explicitly considered in this model, as we show that the analysis is not always feasible due to the required over-dispersion in the resulting negative binomial distribution for the numbers of eruptions. We propose a modification to the method which allows for both over-dispersed and under-dispersed data, and permits analog volcanoes to be chosen on other grounds than mathematical tractability. © 2011 International Association for Mathematical Geosciences. Source

Le Corre D.,Plant and Food Research Ltd. | Angellier-Coussy H.,Montpellier University
Reactive and Functional Polymers | Year: 2014

The increasing scientific and industrial interest for starch nanoparticles (SNP) has led to the development of numerous methods for preparing sub-micron starch fillers for nanocomposites applications. Starch nanocrystals (SNC), which constitute the focus of this review, are one type of SNP with crystalline property and platelet like morphology. SNC can be extracted from various starch botanical sources, allowing to obtain a large range of amylose content, shape, viscosity in suspension, surface reactivity and thermal resistance. To date, the most common method for extracting SNC remains the mild acid hydrolysis of the amorphous parts of native granular starch. So far, alternative methods render much lower yield. Since first publications on SNC, the principal aim is to use them as reinforcement in polymer matrices. Thanks to the reactive nature of starch, SNC surface can be modified by grafting or cross-linking which renders them more readily dispersible in the polymer matrix. The present review focus on the reinforcing effect and mechanisms of SNC, as well as on their impact of barrier properties of polymers. © 2014 Elsevier B.V. All rights reserved. Source

Hofmann R.W.,Agresearch Ltd. | Campbell B.D.,Agresearch Ltd. | Campbell B.D.,Plant and Food Research Ltd.
Environmental and Experimental Botany | Year: 2012

Pasture plants such as Trifolium repens L. (white clover) are exposed to high levels of ultraviolet-B (UV-B) radiation in summer, as well as to frequent defoliation events from grazing animals and pests. This study examined responses in two T. repens populations exposed to 16 weeks supplementation of 0 or 13.3kJm -2d -1 UV-B radiation under controlled environmental conditions. During that period, plants were exposed to two large defoliation events that lasted two and three weeks, respectively. We investigated a number of leaf morphological characteristics, photochemical attributes, as well as aspects of cellular leaf structure. In particular, we sought to explore whether possible differences in these attributes between the two T. repens populations could be related to their UV-B responsiveness. Leaf dry mass decreased by 16% in the UV-B-sensitive cultivar 'Huia' under UV-B, whereas the tolerant ecotype 'Tienshan' was unaffected. This differential UV-B response was related to constitutive differences in leaf mass and in leaf area between the two populations. UV-B did not affect specific leaf mass, whereas leaf dry matter content was reduced by 8% in response to UV-B. Measurements of chlorophyll fluorescence revealed no significant effects of UV-B on photochemistry. Results from light microscopy showed that the cellular leaf structure of the T. repens populations was not damaged by UV-B. Population-specific structural features included more dome-shaped epidermal cells for 'Tienshan'. We conclude that differential UV-B-responses in T. repens populations can occur after defoliation pressure and can be related to differences in leaf characteristics. © 2011 Elsevier B.V.. Source

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