Chagne D.,The New Zealand Institute for Plant and Food Research Ltd |
Crowhurst R.N.,Mount Albert Research Center |
Pindo M.,Instituto Agrario San Michele allAdige Research and Innovation Center |
Thrimawithana A.,Mount Albert Research Center |
And 39 more authors.
PLoS ONE | Year: 2014
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.
Bus V.,Hawkes Bay Research Center |
Brewer L.,Motueka Research Center |
Morgan C.,Motueka Research Center
Acta Horticulturae | Year: 2013
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.
Knabel M.,The New Zealand Institute for Plant and Food Research Ltd |
Knabel M.,University of Auckland |
Friend A.P.,Motueka Research Center |
Palmer J.W.,Motueka Research Center |
And 10 more authors.
BMC Plant Biology | Year: 2015
Background: The vigour and precocity of trees highly influences their efficiency in commercial production. In apple, dwarfing rootstocks allow high-density plantings while their precocious flowering enables earlier fruit production. Currently, there is a lack of pear (Pyrus communis L.) rootstocks that are equivalent to the high yielding apple rootstock 'M9'. For the efficient breeding of new Pyrus rootstocks it is crucial to understand the genetic determinants of vigour control and precocity. In this study we used quantitative trait loci (QTLs) analysis to identify genetic loci associated with the desired traits, using a segregating population of 405 F1 P. communis seedlings from a cross between 'Old Home' and 'Louise Bonne de Jersey' (OHxLBJ). The seedlings were grafted as rootstocks with 'Doyenne du Comice' scions and comprehensively phenotyped over four growing seasons for traits related to tree architecture and flowering, in order to describe the growth of the scions. Results: A high density single nucleotide polymorphism (SNP)-based genetic map comprising 597 polymorphic pear and 113 apple markers enabled the detection of QTLs influencing expression of scion vigour and precocity located on linkage groups (LG)5 and LG6 of 'Old Home'. The LG5 QTL maps to a position that is syntenic to the apple 'Malling 9' ('M9') Dw1 locus at the upper end of LG5. An allele of a simple sequence repeat (SSR) associated with apple Dw1 segregated with dwarfing and precocity in pear and was identified in other pear germplasm accessions. The orthology of the vigour-controlling LG5 QTL between apple and pear raises the possibility that the dwarfing locus Dw1 arose before the divergence of apple and pear, and might therefore be present in other Rosaceae species. Conclusion: We report the first QTLs associated with vigour control and flowering traits in pear rootstocks. Orthologous loci were found to control scion growth and precocity in apple and pear rootstocks. The application of our results may assist in the breeding process of a pear rootstock that confers both vigour control and precocity to the grafted scion cultivar. © 2015 Knäbel et al.
Volz R.K.,Hawkes Bay Research Center |
Kumar S.,Hawkes Bay Research Center |
Chagne D.,Palmerston North Research Center |
Espley R.,Mt Albert Research Center |
And 2 more authors.
Acta Horticulturae | Year: 2013
The genetic relationships between 'Type 1' red flesh and several fruit quality traits in apple were assessed in breeding populations that segregated in the field for white and red flesh. Transgenic plants grown in the glasshouse and genetically modified with the MdMYB10 gene, responsible for the 'Type 1' red flesh phenotype, were also examined. Moderate positive genetic correlations were found in each of two seedling populations between the amount of red colour estimated in the cortical flesh of fruit (WCI) and astringent taste and an internal flesh browning disorder (IFBD) observed in fruit after medium-term cold storage. In one family, a quantitative trait locus for astringent taste and IFBD was mapped to the same position at the bottom of linkage group (LG) 9 as that for WCI and MdMYB10. Fruit from 'Royal Gala' trees that had been transformed with 35S-MdMYB10 had high flesh anthocyanin concentrations but also showed considerable IFBD after cold storage. In contrast, white flesh 'Royal Gala' control fruit did not show any cortical MdMYB10 expression or IFBD symptoms and had minimal flesh anthocyanin concentrations. These results are discussed with regards to future breeding strategies that aim to optimize fruit quality in 'Type 1' red flesh breeding lines.
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 | Year: 2010
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.
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 | Year: 2012
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.
El-Sayed A.M.,The New Zealand Institute for Plant and Food Research Ltd |
Unelius C.R.,The New Zealand Institute for Plant and Food Research Ltd |
Unelius C.R.,Linnaeus University |
Twidle A.,The New Zealand Institute for Plant and Food Research Ltd |
And 7 more authors.
Tetrahedron Letters | Year: 2010
Headspace volatiles collected from virgin females of the citrophilous mealybug, Pseudococcus calceolariae, contain three compounds not present in the headspace of control samples. The main female-specific compound is identified as [2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropyl]methyl 2-acetoxy-3-methylbutanoate (chrysanthemyl 2-acetoxy-3-methylbutanoate). The other two compounds are identified as [2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropyl]methanol (chrysanthemol) and [2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropyl]methyl 2-hydroxy-3-methylbutanoate (chrysanthemyl 2-hydroxy-3-methylbutanoate). Traps baited with 100 μg and 1000 μg of chrysanthemyl 2-acetoxy-3-methylbutanoate captured 4- and 20-fold more males than traps baited with virgin females. © 2009 Elsevier Ltd. All rights reserved.
Montanari S.,Research and Innovation Center |
Montanari S.,CNRS Research Institute on Horticulture and Seeds |
Montanari S.,The New Zealand Institute for Plant and Food Research Ltd |
Perchepied L.,CNRS Research Institute on Horticulture and Seeds |
And 9 more authors.
Molecular Breeding | Year: 2016
Fire blight, caused by the bacterium Erwinia amylovora (Burrill) Winslow et al., is one of the most serious diseases of pear. The development of pear cultivars with a durable resistance is extremely important for effective control of fire blight and is a key objective of most pear breeding programs throughout the world. We phenotyped seedlings from the interspecific pear population PEAR3 (PremP003, P. × bretschneideri × P. communis) × ‘Moonglow’ (P. communis) for fire blight resistance at two different geographic locations, in France and New Zealand, respectively, employing two local E. amylovora isolates. Using a genetic map constructed with single nucleotide polymorphism (SNP) and microsatellite (SSR) markers previously developed for this segregating population, we detected a major quantitative trait locus (QTL) on linkage group (LG)2 of ‘Moonglow’ (R2 = 12.9–34.4 %), which was stable in both environments. We demonstrated that this QTL co-localizes with another major QTL for fire blight resistance previously detected in ‘Harrow Sweet’ and that the two favorable (i.e., resistant) alleles were not identical by descent. We also identified some smaller effect (R2 = 8.1–14.8 %) QTLs derived from the susceptible parent PEAR3. We propose SNP and SSR markers linked to the large effect QTL on LG2 as candidates for marker-assisted breeding for fire blight resistance in pear. © 2016, Springer Science+Business Media Dordrecht.
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 | Year: 2012
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.
Tustin D.S.,The New Zealand Institute for Plant and Food Research Ltd |
Tustin D.S.,Hawkes Bay Research Center |
Seymour S.M.,The New Zealand Institute for Plant and Food Research Ltd |
Seymour S.M.,Riwaka Research Center |
And 2 more authors.
Acta Horticulturae | Year: 2014
Contemporary dwarfing and semi-dwarfing rootstocks cultivated extensively worldwide lack durable resistance to economically damaging pests and diseases. In recognition of these limitations, a series of hybrid families was created in 1986-87 by crossing resistance sources Malus 'Robusta 5' and 'Aotea' (Malus seiboldii) to maternal parent 'Malling 9' (M.9) dwarf rootstock. More than 10,000 genotypes were screened as young seedlings for Phytophthora cactorum tolerance and the survivors established as individual stoolbeds. After three years, those individuals exhibiting field resistance to natural infestation by woolly apple aphid (WAA) (Eriosoma lanigerum) and freedom from spines/branches were grafted with the scion 'Gala' and planted in a replicated agronomic performance trial. The evaluation site was chosen to have a high natural disease pressure for Phytophthora cactorum and periods of waterlogging. After five years, about 15 genotypes were identified for their reduced tree stature, freedom from suckering, continued WAA resistance, freedom from Phytophthora symptoms and high floral and fruiting precocity. Currently, seven selections have been retained in advanced evaluation orchard productivity and adaptability trials, compared with standards M.9 and Geneva® 210. Five of the seven selections show immunity or resistance to fire blight (Erwinia amylovora) in shoot inoculation bioassays. Tree size, productivity and fruit quality comparisons with M.9 and Geneva 210 are presented. Three of the selections are similar in stature to M.9, three selections are semidwarfing, similar or slightly smaller than Geneva 210 and one is more vigorous than Geneva 210 but judged to be less vigorous than MM.106. International development of these rootstock selections is being conducted in collaboration with International Fruit Obtention (IFO).