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Costa F.,Research and Innovation Center | Cappellin L.,Research and Innovation Center | Longhi S.,Research and Innovation Center | Guerra W.,Laimburg Research Center for Agriculture and Forestry | And 7 more authors.
Postharvest Biology and Technology | Year: 2011

Texture of apple fruit originates from anatomic traits related to cell wall architecture and is one of its most important quality characteristics, thus there is the desire to better understand the different factors which contribute to apple texture. Here we present a novel approach based on the simultaneous profiling of the mechanical and acoustic response of the flesh tissue to compression, using a texture analyzer coupled with an acoustic device. The methodology was applied to a 86 different apple cultivars, measured after two months postharvest cold storage and characterised by 16 acoustic and mechanical parameters. Statistical treatment of the data with principal component analysis (PCA) allowed for the identification of three groups of variables, the mechanical ones being clearly distinguished from the acoustic ones. Moreover, the distribution of the apple cultivars in the multivariate PCA plot allowed characterisation of the cultivars according to their textural performance. Each cultivar was analyzed also with non-destructive vis/NIR spectroscopy in order to determine impartially the ripening stage. Sensory evaluation by panellists was performed on a selected group of cultivars and sensory data correlated with the acoustic-mechanical data. The results demonstrate the good performance of our combined acoustic-mechanical strategy in measuring apple crispness as it is perceived by human senses. © 2011 Elsevier B.V.

Costa F.,Research and Innovation Center | Cappellin L.,Research and Innovation Center | Fontanari M.,Research and Innovation Center | Longhi S.,Research and Innovation Center | And 4 more authors.
Postharvest Biology and Technology | Year: 2012

Texture is a principal quality factor and represents one of the main priorities in apple postharvest management and breeding programs designed for the creation of new ideotypes defined by a better fruit quality and extended storability. The apple panorama is characterized by a great variability of texture performance due to specific functional regulation and genetic control of the physiological machinery devoted to the degradation of the polysaccharide architecture of the middle lamella/cell wall structure. In this work we present an investigation of texture dynamics in apple, in terms of variation of several texture components dissected over two months of postharvest storage. Apple texture was assessed at harvest and after storage, by acquiring both mechanical and acoustic profiles in a collection of 83 apple cultivars. The general texture variability, illustrated over the reduced hyperspace defined by principal components, revealed a different variety distribution between the two stages. Time evolution plots and the novel storage index presented here highlighted that each single texture component behaves differently, as seen by some cultivars (i.e. 'Fuji') having a more favourable acoustic response after postharvest. The dissected fruit texture dynamics assessed in a set of reference apple cultivars are discussed. © 2012 Elsevier B.V.

Prange R.K.,Dalhousie University | Wright A.H.,Laval University | DeLong J.M.,Agriculture and Agri Food Canada | Zanella A.,Laimburg Research Center for Agriculture and Forestry
Acta Horticulturae | Year: 2013

The use of chlorophyll fluorescence in fruit and vegetable storage (HarvestWatch™) was first introduced at the ISHS CA symposium in 2001 in Rotterdam, The Netherlands and was first commercially adopted in the 2003-2004 storage season in Washington State, USA and South Tyrol, Italy. Although there are many potential postharvest applications for chlorophyll fluorescence that will be reviewed, research and commercial adoption has focussed primarily on its use in optimising the O2 concentration in dynamic controlled-atmosphere (DCA) storage of fruits and vegetables. This is achieved through a novel method of detection of a sudden change in fluorescence at the lower O2 limit (LOL). The reasons for its adoption are: real-time monitoring and control of product, pesticide-free technique, accurate determination of LOL, control of storage disorders, especially superficial scald in susceptible apple and pear cultivars without use of pesticides such as diphenylamine (DPA), improved retention of quality, possible flavour enhancement and detection of senescence, decay or incorrect storage conditions, i.e., temperature. A summary of the current use of HarvestWatch™ will be presented. Preliminary results from applications in other high value fruits, e.g., extension of green-life in banana, 'programmed DCA' for avocado, will be presented as evidence of possible future applications.

Schinko T.,University of Natural Resources and Life Sciences, Vienna | Gallmetzer A.,University of Natural Resources and Life Sciences, Vienna | Gallmetzer A.,Laimburg Research Center for Agriculture and Forestry | Amillis S.,University of Natural Resources and Life Sciences, Vienna | And 3 more authors.
Fungal Genetics and Biology | Year: 2013

In fungi, transcriptional activation of genes involved in NO3- assimilation requires the presence of an inducer (nitrate or nitrite) and low intracellular concentrations of the pathway products ammonium or glutamine. In Aspergillus nidulans, the two transcription factors NirA and AreA act synergistically to mediate nitrate/nitrite induction and nitrogen metabolite derepression, respectively. In all studied fungi and in plants, mutants lacking nitrate reductase (NR) activity express nitrate-metabolizing enzymes constitutively without the addition of inducer molecules. Based on their work in A. nidulans, Cove and Pateman proposed an " autoregulation control" model for the synthesis of nitrate metabolizing enzymes in which the functional nitrate reductase molecule would act as co-repressor in the absence and as co-inducer in the presence of nitrate. However, NR mutants could simply show " pseudo-constitutivity" due to induction by nitrate which accumulates over time in NR-deficient strains. Here we examined this possibility using strains which lack flavohemoglobins (fhbs), and are thus unable to generate nitrate internally, in combination with nitrate transporter mutations (nrtA, nrtB) and a GFP-labeled NirA protein. Using different combinations of genotypes we demonstrate that nitrate transporters are functional also in NR null mutants and show that the constitutive phenotype of NR mutants is not due to nitrate accumulation from intracellular sources but depends on the activity of nitrate transporters. However, these transporters are not required for nitrate signaling because addition of external nitrate (10. mM) leads to standard induction of nitrate assimilatory genes in the nitrate transporter double mutants. We finally show that NR does not regulate NirA localization and activity, and thus the autoregulation model, in which NR would act as a co-repressor of NirA in the absence of nitrate, is unlikely to be correct. Results from this study instead suggest that transporter-mediated NO3- accumulation in NR deficient mutants, originating from traces of nitrate in the media, is responsible for the constitutive expression of NirA-regulated genes, and the associated phenotype is thus termed " pseudo-constitutive" © 2013 Elsevier Inc.

Longhi S.,Research and Innovation Center | Cappellin L.,Research and Innovation Center | Guerra W.,Laimburg Research Center for Agriculture and Forestry | Costa F.,Research and Innovation Center
Molecular Breeding | Year: 2013

Molecular markers are nowadays considered fundamental tools in breeding programs, supporting the selection of the most favourable offspring. This role is invaluable in the case of complex agronomic traits in tree fruit crop species, such as fruit texture in apple (Malus × domestica Borkh.). This work presents the validation of a previously identified functional simple sequence repeat marker, named Md-PG1SSR10kd, suitable for the advanced selection of high texture performance seedlings. Two independent populations were chosen by marker-assisted parent selection, and a specific set of seedlings was selected by marker-assisted seedling selection, to validate the predictive power of this marker. The two groups of seedlings, further phenotyped for fruit texture, showed a clear difference in texture behaviour. The selection of this marker also showed a higher efficiency than Md-ACS1 and Md-ACO1, two functional markers currently implemented in different breeding programs. Finally, the allelic effect was estimated by computing the breeding values in a collection of 83 different apple cultivars. The results reported here confirmed the association of Md-PG1SSR10kd with texture sub-traits, proposing this as a novel promising selection strategy suitable for apple fruit texture. © 2013 Springer Science+Business Media Dordrecht.

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