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Havelock North, New Zealand

Palmer J.,The New Zealand Institute for Plant and Food Research Ltd | Lozano L.,IRTA - Institute of Agricultural-Alimentary Research and Technology | Chagne D.,Palmerston North Research Center | Volz R.,Hawkes Bay Research Center | And 8 more authors.
Acta Horticulturae

The biosynthesis of anthocyanins in many plant species is affected by environmental conditions. In apple fruit, skin anthocyanin contents are lower under hot climate conditions. We have examined anthocyanin accumulation in maturing 'Royal Gala' apples grown under temperate and hot conditions. Orchard-based apple heating to temperatures comparable to hot climates was performed and found to cause fast fruit colour loss and a reduction in anthocyanin content. Lower rates of biosynthesis are suggested, as a coordinative down-regulation of gene expression of the genes encoding the anthocyanin biosynthetic pathway occurs in hot conditions. In addition, the expression of the genes encoding the transcriptional activation complex is also reduced. Heating fruit rapidly reduced expression of apple anthocyanin-related genes, which correlated with a reduction in expression of the R2R3 MYB transcription factor (MYB10/MYB1) responsible for elevating apple colour. A genetic mapping strategy was used to identify loci associated with the expression of red skin colour under high temperatures. A population of apple seedlings was phenotyped for skin colour and anthocyanin content and then genotyped using a panel of SNP markers spanning the entire apple genome. Two markers were associated with red skin colour on linkage groups 9 and 17, including a marker located close to MYB10 (LG 9). We propose that temperature-induced down-regulation of fruit anthocyanin biosynthesis is primarily due to down-regulation of the anthocyanin regulatory complex, and that the genes encoding the complex have become useful loci for the development of marker assisted breeding of new apple cultivars tolerant of warm conditions. Source

Palmer J.W.,The New Zealand Institute for Plant and Food Research Ltd | Harker F.R.,Mt Albert Research Center | Tustin D.S.,Hawkes Bay Research Center | Johnston J.,Mt Albert Research Center
Journal of the Science of Food and Agriculture

In the fresh apple market fruit must be crisp and juicy to attract buyers to purchase again. However, recent studies have shown that consumer acceptability could be further enhanced by improving taste. This study evaluates the use of fruit dry matter concentration (DMC) as a new fruit quality metric for apple. RESULTS: Fruit samples collected at harvest, in the two main fruit growing regions of New Zealand, showed a variation in mean fruit DMC from 130 to 156 g kg-1 with 'Royal Gala' and with 'Scifresh' from 152 to 176 g kg-1. Individual fruit DMC showed a larger range, from 108 to 189 g kg-1 with 'Royal Gala' and from 125 to 201 g kg-1 with 'Scifresh'. Fruit DMC proved a more reliable predictor of total soluble solids after 12 weeks of air storage at 0.5 °C than TSS at harvest for both 'Royal Gala' and 'Scifresh'. Fruit DMC was also positively related to flesh firmness, although this relationship was not as strong as that seen with soluble solids and was more dependent on cultivar. Consumer studies showed that consumer preference was positively related to fruit DMC of 'Royal Gala' apples. CONCLUSION: Fruit DMC can therefore be measured before or at harvest, and be used to predict the sensory potential for the fruit after storage. © 2010 Society of Chemical Industry. Source

Bus V.,Hawkes Bay Research Center | Brewer L.,Motueka Research Center | Morgan C.,Motueka Research Center
Acta Horticulturae

Scab is a major disease of pear worldwide. The disease is caused by two species: Venturia pirina, which infects European pear, and V. nashicola, which infects Asian pear species. The host types are mutually exclusive to the Venturia species and this phenomenon is heavily exploited in the Plant & Food Research pear breeding programme for the breeding of scab-resistant pear cultivars. In 2008 and 2009, 18 seedling families with a range of 0 to 100% Asian pear pedigree were screened in the glasshouse following artificial inoculation with V. pirina, the scab species present in New Zealand. The progenies showed a range of resistance reactions, mostly in the classes 0 (no symptoms) and 2 (necrotic reaction without sporulation). Some seedlings showed a hypersensitive response (class 1) or chlorotic reactions with limited sporulation (class 3). As expected, the seedling progenies of low Asian pear descent showed high proportions (78-91%) of susceptible seedlings. Ten families showed 100% resistant seedlings, with a further two families showing 98 and 94% resistance. We show that the average proportion of Asian ancestry of a progeny estimated from their parents is not necessarily a good predictor for the expected resistance segregations of that progeny. Source

Chagne D.,The New Zealand Institute for Plant and Food Research Ltd | Crowhurst R.N.,Mount Albert Research Center | Pindo M.,Istituto Agrario San Michele allAdige Research and Innovation Center | Thrimawithana A.,Mount Albert Research Center | And 39 more authors.

We present a draft assembly of the genome of European pear (Pyrus communis) 'Bartlett'. Our assembly was developed employing second generation sequencing technology (Roche 454), from single-end, 2 kb, and 7 kb insert paired-end reads using Newbler (version 2.7). It contains 142,083 scaffolds greater than 499 bases (maximum scaffold length of 1.2 Mb) and covers a total of 577.3 Mb, representing most of the expected 600 Mb Pyrus genome. A total of 829,823 putative single nucleotide polymorphisms (SNPs) were detected using re-sequencing of 'Louise Bonne de Jersey' and 'Old Home'. A total of 2,279 genetically mapped SNP markers anchor 171 Mb of the assembled genome. Ab initio gene prediction combined with prediction based on homology searching detected 43,419 putative gene models. Of these, 1219 proteins (556 clusters) are unique to European pear compared to 12 other sequenced plant genomes. Analysis of the expansin gene family provided an example of the quality of the gene prediction and an insight into the relationships among one class of cell wall related genes that control fruit softening in both European pear and apple (Malusxdomestica). The 'Bartlett' genome assembly v1.0 (http://www.rosaceae.org/species/pyrus/ pyrus-communis/genome-v1.0) is an invaluable tool for identifying the genetic control of key horticultural traits in pear and will enable the wide application of marker-assisted and genomic selection that will enhance the speed and efficiency of pear cultivar development. © 2014 Chagné et al. Source

Ampomah-Dwamena C.,The New Zealand Institute for Plant and Food Research Ltd | Dejnoprat S.,The New Zealand Institute for Plant and Food Research Ltd | Lewis D.,Palmerston North Research Center | Sutherland P.,The New Zealand Institute for Plant and Food Research Ltd | And 3 more authors.
Journal of Experimental Botany

Carotenoid accumulation confers distinct colouration to plant tissues, with effects on plant response to light and as well as health benefits for consumers of plant products. The carotenoid pathway is controlled by flux of metabolites, rate-limiting enzyme steps, feed-back inhibition, and the strength of sink organelles, the plastids, in the cell. In apple (Malus × domestica Borkh), fruit carotenoid concentrations are low in comparison with those in other fruit species. The apple fruit flesh, in particular, begins development with high amounts of chlorophylls and carotenoids, but in all commercial cultivars a large proportion of this is lost by fruit maturity. To understand the control of carotenoid concentrations in apple fruit, metabolic and gene expression analysis of the carotenoid pathway were measured in genotypes with varying flesh and skin colour. Considerable variation in both carotenoid concentrations and compound profile was observed between tissues and genotypes, with carotenes and xanthophylls being found only in fruit accumulating high carotenoid concentrations. The study identified potential rate-limiting steps in carotenogenesis, which suggested that the expression of ZISO, CRTISO, and LCY-ε, in particular, were significant in predicting final carotenoid accumulation in mature apple fruit. © 2012 The Authors. Source

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