Havelock North, New Zealand
Havelock North, New Zealand
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Hall A.J.,The New Zealand Institute for Plant and Food Research Ltd | Minchin P.E.H.,PFR | Clearwater M.J.,University of Waikato | Genard M.,French National Institute for Agricultural Research
Journal of Experimental Botany | Year: 2013

A model of kiwifruit berry development is presented, building on the model of Fishman and Génard used for peach fruit. That model has been extended to incorporate a number of important features of kiwifruit growth. First, the kiwifruit berry is attached to the stem through a pedicel/receptacle complex which contributes significantly to the hydraulic resistance between the stem and the fruit, and this resistance changes considerably during the season. Second, much of the carbohydrate in kiwifruit berries is stored as starch until the fruit matures late in the season, when the starch hydrolyses to soluble sugars. This starch storage has a major effect on the osmotic potential of the fruit, so an existing model of kiwifruit starch dynamics was included in the model. Using previously published approaches, we also included elasticity and extended the modelling period to cover both the cell division and cell expansion phases of growth. The resulting model showed close simulation of field observations of fresh weight, dry matter, starch, and soluble solids in kiwifruit. Comparison with continuous measurements of fruit diameter confirmed that elasticity was needed to adequately simulate observed diurnal variation in fruit size. Sensitivity analyses suggested that the model is particularly sensitive to variation in inputs relating to water (stem water potential and the humidity of the air), and to parameters controlling cell expansion (cell wall extensibility). Some limitations in the model structure were identified, suggesting that a revised model including current apoplastic/symplastic concepts needs to be developed. © The Author 2013. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Yauk Y.-K.,The New Zealand Institute for Plant and Food Research Ltd | Ged C.,The New Zealand Institute for Plant and Food Research Ltd | Ged C.,National Polytechnic Institute of Toulouse | Wang M.Y.,The New Zealand Institute for Plant and Food Research Ltd | And 7 more authors.
Plant Journal | Year: 2014

Glycosides are an important potential source of aroma and flavour compounds for release as volatiles in flowers and fruit. The production of glycosides is catalysed by UDP-glycosyltransferases (UGTs) that mediate the transfer of an activated nucleotide sugar to acceptor aglycones. A screen of UGTs expressed in kiwifruit (Actinidia deliciosa) identified the gene AdGT4 which was highly expressed in floral tissues and whose expression increased during fruit ripening. Recombinant AdGT4 enzyme glycosylated a range of terpenes and primary alcohols found as glycosides in ripe kiwifruit. Two of the enzyme's preferred alcohol aglycones, hexanol and (Z)-hex-3-enol, contribute strongly to the 'grassy-green' aroma notes of ripe kiwifruit and other fruit including tomato and olive. Transient over-expression of AdGT4 in tobacco leaves showed that enzyme was able to glycosylate geraniol and octan-3-ol in planta whilst transient expression of an RNAi construct in Actinidia eriantha fruit reduced accumulation of a range of terpene glycosides. Stable over-expression of AdGT4 in transgenic petunia resulted in increased sequestration of hexanol and other alcohols in the flowers. Transgenic tomato fruit stably over-expressing AdGT4 showed changes in both the sequestration and release of a range of alcohols including 3-methylbutanol, hexanol and geraniol. Sequestration occurred at all stages of fruit ripening. Ripe fruit sequestering high levels of glycosides were identified as having a less intense, earthier aroma in a sensory trial. These results demonstrate the importance of UGTs in sequestering key volatile compounds in planta and suggest a future approach to enhancing aromas and flavours in flowers and during fruit ripening. © 2014 The Authors.

Bushakra J.M.,The New Zealand Institute for Plant and Food Research Ltd | Bushakra J.M.,Massey University | Stephens M.J.,PFR | Atmadjaja A.N.,The New Zealand Institute for Plant and Food Research Ltd | And 6 more authors.
Theoretical and Applied Genetics | Year: 2012

The genus Rubus belongs to the Rosaceae and is comprised of 600-800 species distributed world-wide. To date, genetic maps of the genus consist largely of non-transferable markers such as amplified fragment length polymorphisms. An F1 population developed from a cross between an advanced breeding selection of Rubus occidentalis (96395S1) and R. idaeus 'Latham' was used to construct a new genetic map consisting of DNA sequence-based markers. The genetic linkage maps presented here are constructed of 131 markers on at least one of the two parental maps. The majority of the markers are orthologous, including 14 Rosaceae conserved orthologous set markers, and 60 new gene-based markers developed for raspberry. Thirty-four published raspberry simple sequence repeat markers were used to align the new maps to published raspberry maps. The 96395S1 genetic map consists of six linkage groups (LG) and covers 309 cM with an average of 10 cM between markers; the 'Latham' genetic map consists of seven LG and covers 561 cM with an average of 5 cM between markers. We used BLAST analysis to align the orthologous sequences used to design primer pairs for Rubus genetic mapping with the genome sequences of Fragaria vesca 'Hawaii 4', Malus × domestica 'Golden Delicious', and Prunus 'Lovell'. The alignment of the orthologous markers designed here suggests that the genomes of Rubus and Fragaria have a high degree of synteny and that synteny decreases with phylogenetic distance. Our results give unprecedented insights into the genome evolution of raspberry from the putative ancestral genome of the single ancestor common to Rosaceae. © 2012 Springer-Verlag.

News Article | August 22, 2016

Flexible electronics with highly thermal stability and mechanical strength are highly needed in advanced transportation systems. Semiconducting single-walled carbon nanotubes are one of the leading active materials for such thin film transistors because they are printable, flexible, thermally stable, and mechanically strong. Dielectrics with large capacitance are another major component, and polymer electrolytes are printed for flexible electronics, but they suffer from poor mechanical strength and low operating temperature. Here, a transparent, mechanically flexible, and thermally stable polyfluorinated electrolyte (PFE) is developed with high capacitance by curing printed polyfluorinated resin (PFR) and ionic liquid composite at high temperature. PFE inherits the mechanical flexibility and thermal stability from PFR. The immobilized ionic liquid inside the porous structures of PFE accounts for the high capacitance. With top-gated PFE, fully printed electronically pure single-chirality (6,5) single-walled carbon nanotube (SWCNT) thin-film transistors (TFTs) exhibit air stable, consistent, and reliable ambipolar characteristics with high transconductance (1 mS) and small subthreshold swing (<0.15 V dec−1) at low voltage in ambient air for p-type and n-type carriers, and >105 ON/OFF current ratio for both carriers under low operation voltage.

Hall A.J.,The New Zealand Institute for Plant and Food Research Ltd | Minchin P.E.H.,PFR
Plant, Cell and Environment | Year: 2013

A closed-form solution for steady-state coupled phloem/xylem flow is presented. This incorporates the basic Münch flow model of phloem transport, the cohesion model of xylem flow, and local variation in the xylem water potential and lateral water flow along the transport pathway. Use of the Lambert-W function allows this solution to be obtained under much more general and realistic conditions than has previously been possible. Variation in phloem resistance (i.e. viscosity) with solute concentration, and deviations from the Van't Hoff expression for osmotic potential are included. It is shown that the model predictions match those of the equilibrium solution of a numerical time-dependent model based upon the same mechanistic assumptions. The effect of xylem flow upon phloem flow can readily be calculated, which has not been possible in any previous analytical model. It is also shown how this new analytical solution can handle multiple sources and sinks within a complex architecture, and can describe competition between sinks. The model provides new insights into Münch flow by explicitly including interactions with xylem flow and water potential in the closed-form solution, and is expected to be useful as a component part of larger numerical models of entire plants. © 2013 John Wiley & Sons Ltd.

Zhang H.,The New Zealand Institute for Plant and Food Research Ltd | Wang L.,The New Zealand Institute for Plant and Food Research Ltd | Hunter D.,The New Zealand Institute for Plant and Food Research Ltd | Voogd C.,PFR | And 2 more authors.
Plant Methods | Year: 2013

Background: With the explosive numbers of sequences generated by next generation sequencing, the demand for high throughput screening to understand gene function has grown. Plant viral vectors have been widely used as tools in down-regulating plant gene expression. However, plant viral vectors can also express proteins in a very efficient manner and, therefore, can also serve as a valuable tool for characterizing proteins and their functions in metabolic pathways in planta.Results: In this study, we have developed a Gateway®-based high throughput viral vector cloning system from Narcissus Mosaic Virus (NMV). Using the reporter genes of GFP and GUS, and the plant genes PAP1 (an R2R3 MYB which activates the anthocyanin pathway) and selenium-binding protein 1 (SeBP), we show that NMV vectors and the model plant Nicotiana benthamiana can be used for efficient protein expression, protein subcellular localization and secondary metabolite production.Conclusions: Our results suggest that not only can the plant viral vector system be employed for protein work but also can potentially be amenable to producing valuable secondary metabolites on a large scale, as the system does not require plant regeneration from seed or calli, which are stages where certain secondary metabolites can interfere with development. © 2013 Zhang et al.; licensee BioMed Central Ltd.

Atkinson R.G.,The New Zealand Institute for Plant and Food Research Ltd | Gunaseelan K.,The New Zealand Institute for Plant and Food Research Ltd | Wang M.Y.,The New Zealand Institute for Plant and Food Research Ltd | Luo L.,The New Zealand Institute for Plant and Food Research Ltd | And 6 more authors.
Journal of Experimental Botany | Year: 2011

During climacteric fruit ripening, autocatalytic (Type II) ethylene production initiates a transcriptional cascade that controls the production of many important fruit quality traits including flavour production and softening. The last step in ethylene biosynthesis is the conversion of 1-aminocyclopropane- 1-carboxylic acid (ACC) to ethylene by the enzyme ACC oxidase (ACO). Ten independent kiwifruit (Actinidia chinensis) lines were generated targeting suppression of fruit ripening-related ACO genes and the fruit from one of these lines (TK2) did not produce detectable levels of climacteric ethylene. Ripening behaviour in a population of kiwifruit at harvest is asynchronous, so a short burst of exogenous ethylene was used to synchronize ripening in TK2 and control fruit. Following such a treatment, TK2 and control fruit softened to an 'eating-ripe' firmness. Control fruit produced climacteric ethylene and softened beyond eating-ripe by 5 d. In contrast, TK2 fruit maintained an eating-ripe firmness for >25 d and total volatile production was dramatically reduced. Application of continuous exogenous ethylene to the ripening-arrested TK2 fruit re-initiated fruit softening and typical ripe fruit volatiles were detected. A 17 500 gene microarray identified 401 genes that changed after ethylene treatment, including a polygalacturonase and a pectate lyase involved in cell wall breakdown, and a quinone oxidoreductase potentially involved in volatile production. Many of the gene changes were consistent with the softening and flavour changes observed after ethylene treatment. However, a surprisingly large number of genes of unknown function were also observed, which could account for the unique flavour and textural properties of ripe kiwifruit. © 2011 The Author(s).

Maddumage R.,The New Zealand Institute for Plant and Food Research Ltd | Nieuwenhuizen N.J.,The New Zealand Institute for Plant and Food Research Ltd | Bulley S.M.,The New Zealand Institute for Plant and Food Research Ltd | Cooney J.M.,PFR | And 2 more authors.
Journal of Agricultural and Food Chemistry | Year: 2013

In the last 30 years the incidence of kiwifruit allergy has increased with the three major allergenic proteins being identified as actinidin, kiwellin, and thaumatin-like protein (TLP). We report wide variation in the levels of actinidin and TLP in 15 kiwifruit varieties from the four most widely cultivated Actinidia species. Acidic and basic isoforms of actinidin were identified in Actinidia deliciosa 'Hayward' and Actinidia arguta 'Hortgem Tahi', while only a basic isoform of actinidin was identified in Actinidia chinensis 'Hort16A'. One isoform each of kiwellin and TLP were identified in ripe fruit. The cysteine protease activity of actinidin correlated with protein levels in all species except A. arguta. Protein modeling suggested that modifications to the S2 binding pocket influenced substrate specificity of the A. arguta enzyme. Our results indicate that care is necessary when extrapolating allergenicity results from single varieties to others within the same and between different Actinidia species. © 2013 American Chemical Society.

Hill M.G.,The New Zealand Institute for Plant and Food Research Ltd | Connolly P.G.,PFR | Reutemann P.,University of Waikato | Fletcher D.,University of Waikato
Computers and Electronics in Agriculture | Year: 2014

Data mining algorithms were used to develop models to forecast the outcome of leafroller pest monitoring decisions on 'Hayward' kiwifruit crops in New Zealand. Using industry spray diary and pest monitoring data gathered at an orchard block level for compliance purposes, 80 attributes (independent variables) were created in three categories from the spray diary data: (1) individual insecticide applications applied during 2-week time windows, (2) groups of insecticide applications within time periods prior to or after fruit set and (3) orchard management attributes. Five machine learning algorithms (Decision Tree, Naïve Bayes, Random Forest, AdaBoost, Support Vector Machine) and one statistical method (Logistic regression) (classifiers) were used to develop models to forecast insecticide application decisions for leafroller control, by predicting whether pest monitoring results were above or below a spray threshold. Models to forecast 2011 spraying decisions were trained on 2008 and 2009 data and tested on 2010 data. Forecasts were made for spray and no-spray decisions based upon pre-determined acceptable rates of precision (proportion of correct decisions in test results). Orchard blocks in which a forecast could not be made to a prescribed degree of precision were recommended to be monitored, which is the normal practice. Spray decisions could not be forecast to an acceptable degree of precision, but decisions not to spray were successfully forecast for 49% of the blocks to a precision of 98% (AdaBoost) and 70% of the blocks to a precision of 95% (Naïve Bayes). Models with as few as four attributes gave useful forecasts, and orchard management attributes were the most important determinants of model forecasting accuracy. The potential for this methodology to assist with pest spray forecasting using customised data sets is discussed. © 2014 Elsevier B.V.

Amponsah N.T.,The New Zealand Institute for Plant and Food Research Ltd | Walter M.,The New Zealand Institute for Plant and Food Research Ltd | Scheper R.W.A.,PFR
New Zealand Plant Protection | Year: 2014

European canker pathogen, caused by the fungus Neonectria ditissima, could not be isolated when infected woody tissues were plated directly onto potato dextrose agar (PDA), malt extract agar (MEA) or acidified PDA (pH 4.5). However, the alternative media, water agar (WA) and apple sap-amended water agar (ASAWA), were successfully used to isolate the pathogen. In the preparation of ASAWA, green shoots of 1-year-old fresh 'Scilate' apple were frozen overnight then allowed to thaw. The tissues were then centrifuged and the sap collected to prepare the medium. Neonectria ditissima could be isolated from both symptomatic and asymptomatic apple tissues on both WA and ASAWA. Both media supported the production of large numbers of conidia in vitro, with more conidia being produced on ASAWA than on WA. The conidia produced in vitro had morphological characteristics and pathogenicity similar to those produced in the field. © 2014 New Zealand Plant Protection Society (Inc.).

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