Multielement authentication of apples from the cold highlands in southwest China

BACKGROUND

Half of all apple production worldwide comes from China. However, the geographic authentication of Chinese apples has not been well studied. We highlight the multi-element-based geographical discrimination of apples from the southwest cold highlands (SCH) of China. 565 samples from the SCH (138) and others (427) were obtained, and the content of fifteen elements were applied to construct models for discrimination.

RESULTS

The SCH apples from 2017 to 2019 had higher concentrations of Mn, Zn, Cr, Cd, Se, Pb, and Fe, but lower concentrations of Na, B, Ni, and P. With sufficient training, linear discriminant analysis (LDA) discriminated the SCH, and the testing accuracy averaged 92.5% and 92.2%. Nonlinear discrimination models were more suitable than the linear models. Optimized random forest analysis was the model with the best fit, and with averaged training and testing it obtained a level of accuracy of 98.2% and 98.5%.

CONCLUSION

The multielement-based discrimination of SCH apples could aid further studies of geographical origins. © 2021 Society of Chemical Industry.

Genome-Wide Analysis of the Apple CBL Family Reveals That Mdcbl10.1 Functions Positively in Modulating Apple Salt Tolerance

Abiotic stresses are increasingly harmful to crop yield and quality. Calcium and its signaling pathway play an important role in modulating plant stress tolerance. As specific Ca²⁺ sensors, calcineurin B-like (CBL) proteins play vital roles in plant stress response and calcium signaling. The CBL family has been identified in many plant species; however, the characterization of the CBL family and the functional study of apple MdCBL proteins in salt response have yet to be conducted in apple. In this study, 11 MdCBL genes were identified from the apple genome. The coding sequences of these MdCBL genes were cloned, and the gene structure and conserved motifs were analyzed in detail. The phylogenetic analysis indicated that these MdCBL proteins could be divided into four groups. The functional identification in Na⁺-sensitive yeast mutant showed that the overexpression of seven MdCBL genes could confer enhanced salt stress resistance in transgenic yeast. The function of MdCBL10.1 in regulating salt tolerance was also verified in cisgenic apple calli and apple plants. These results provided valuable insights for future research examining the function and mechanism of CBL proteins in regulating apple salt tolerance.

Phenotypic variation of floral organs in flowering crabapples and its taxonomic significance

BACKGROUND

In angiosperms, phenotypic variation of floral organs is often considered as the traditional basis for the evolutionary relationship of different taxonomic groups above the species level. However, little is known about that at or below the species level. Here, we experimentally tested the phenotypic variation of Malus floral organs using combined methods of intraspecific uniformity test, interspecific distinctness analysis, principal component analysis, Pearson correlation analysis, and Q-type cluster analysis. The ancestor-inclined distribution characteristic analysis of Malus species and cultivars floral attributes was also carried out, so as to explore its taxonomic significance.

RESULTS

15/44 phenotypic traits (e.g., flower shape, flower type, flower diameter, ...) were highly consistent, distinguishable, and independent and could be used as the basis for Malus germplasm taxonomy. The studied 142 taxa were divided into two groups (A, B) and five sub-groups (A₁, A₂, B₁, B₂, B₃), with significantly variable floral phenotypic attributes between groups and within sub-groups. Malus natural species were relatively clustered in the same section (series) while homologous cultivars showed evidence of ancestor-inclined distribution characteristics. However, no significant correlation between the evolutionary order of sections (Sect. Docyniopsis → Sect. Chloromeles → Sect. Sorbomalus → Sect. Eumalus) and group/sub-groups (B₃ → B₂ → B₁ → A).

CONCLUSIONS

Phenotypic variation of floral organs could better explore the genetic relationship between Malus taxa. The findings improved our cognition of floral phenotypic variation taxonomic significance under the species level.

Multi-chemical analysis combined with chemometrics to characterize PDO and PGI Italian apples

BACKGROUND

The use of PDO (protected designation of origin) and PGI (protected geographical indication) labels allows to protect and promote agricultural products characterized by unique features related to the place of origin and traditional know-how. However, the presence of non-authentic products in the market represents a fraud that can be tackled applying analytical techniques combined with chemometric analysis. In this study, we applied multi-element and multi-isotope analysis to characterize PDO and PGI apples cultivated in northern Italy, comparing them with Italian apples without labels of geographical indications.

RESULTS

The multi-element and multi-isotope approach allowed to characterize the apples cultivated in northern Italy. Despite a significant effect of the sampling sites on the apple composition, the comparison of the multi-chemical fingerprint of the apples significantly varied among cultivation areas. Results of this characterization were used to classify samples according to their cultivation area applying a linear discriminant analysis (LDA). Outputs of the LDA showed that correct sample classification can be successfully achieved (balanced accuracy > 96%). Moreover, using a selection of variables, it was possible to correctly classify samples also at regional level.

CONCLUSION

The presented evidences indicate that the multi-element and multi-isotope fingerprint can be successfully applied to traceability studies. The combination of this characterization with chemometric tools allows the classification of Italian apples based on their origin both on a national and regional scale. This approach represents an interesting tool to enhance and protect PDO and PGI Italian products. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effects of different processing steps on the flavor and colloidal properties of cloudy apple juice

BACKGROUND

Flavor loss is a common problem when manufacturing apple juice and is closely related to the properties of the colloidal pectin particles in cloudy juice. The flavor changes and particle properties of three varieties of apple juice ('Ralls', 'Golden Delicious' and 'Fuji') during processing were investigated.

RESULTS

Compared with manually pressed juice, juice made by industrial pulping and filtration contained larger particles, resulting in the 'sweet and sour' taste of the juice being relatively weak and the diversity of aromas narrower, as determined by E-nose analysis. Pulping and filtration, however, released some important flavor esters, such as butyl butyrate, hexyl-2-methyl butyrate, and hexyl butyrate. The transformation of volatile compounds during apple juice processing was closely related to the apple cultivar but, in all three varieties, the content of 1-hexanal and (E)-2-hexenal in the juice gradually decreased during processing. Pectinase treatment reduced the colloid particle size and increased the ζ-potential of the juice, resulting in better uniformity and stability, as well as increasing the content of nonanal. After pasteurization, the colloidal particles tended to aggregate and the ζ-potential decreased. Many volatile compounds decreased in concentration or disappeared after heat treatment.

CONCLUSION

The flavor and colloidal properties of cloudy apple juice changed markedly during processing and the effect of each processing step was different. © 2020 Society of Chemical Industry.

Development of a minimal KASP marker panel for distinguishing genotypes in apple collections

Accurate identification of named accessions in germplasm collections is extremely important, especially for vegetatively propagated crops which are expensive to maintain. Thus, an inexpensive, reliable, and rapid genotyping method is essential because it avoids the need for laborious and time-consuming morphological comparisons. Single Nucleotide Polymorphism (SNP) marker panels containing large numbers of SNPs have been developed for many crop species, but such panels are much too large for basic cultivar identification. Here, we have identified a minimum set of SNP markers sufficient to distinguish apple cultivars held in the English and Welsh national collections providing a cheaper and automatable alternative to the markers currently used by the community. We show that SNP genotyping with a small set of well selected markers is equally efficient as microsatellites for the identification of apple cultivars and has the added advantage of automation and reduced cost when screening large numbers of samples.

Application of genome-wide insertion/deletion markers on genetic structure analysis and identity signature of Malus accessions

BACKGROUND

Apple (Malus ssp.), one of the most important temperate fruit crops, has a long cultivation history and is economically important. To identify the genetic relationships among the apple germplasm accessions, whole-genome structural variants identified between M. domestica cultivars 'Jonathan' and 'Golden Delicious' were used.

RESULTS

A total of 25,924 insertions and deletions (InDels) were obtained, from which 102 InDel markers were developed. Using the InDel markers, we found that 942 (75.3%) of the 1251 Malus accessions from 35 species exhibited a unique identity signature due to their distinct genotype combinations. The 102 InDel markers could distinguish 16.7-71.4% of the 331 bud sports derived from 'Fuji', 'Red Delicious', 'Gala', 'Golden Delicious', and other cultivars. Five distinct genetic patterns were found in 1002 diploid accessions based on 78 bi-allele InDel markers. Genetic structure analysis indicated that M. domestica showed higher genetic diversity than the other species. Malus underwent a relatively high level of wild-to-crop or crop-to-wild gene flow. M. sieversii was closely related to both M. domestica and cultivated Chinese cultivars.

CONCLUSIONS

The identity signatures of Malus accessions can be used to determine distinctness, uniformity, and stability. The results of this study may also provide better insight into the genetic relationships among Malus species.

Evaluation of the phenolic profile and immunoreactivity of Mal d 3 allergen in ancient apple cultivars from Italy

BACKGROUND

Since the second half of the 20th century, the cultivation of ancient and local apple cultivars has almost disappeared from orchards in Italy. Some of these ancient apple cultivars often possess high nutraceutical values and display lower allergenicity than the modern ones, supporting the so-called 'green revolution' theory.

RESULTS

In this study, the phenolic composition and the antioxidant activity of five ancient apple cultivars ('Belfiore', 'Pomella Genovese', 'Gravenstein', 'Bella del Bosco', and 'Piatlin') were compared with a 'Golden Delicious' commercial cultivar. Additionally, apples were tested for their potential allergenicity by detecting the presence of Mal d 3, a non-specific lipid transfer protein that represents the main apples' allergen. All apples came from northern Italy (Trentino Region) and were organically produced. Results showed that, for all cultivars, the skins contained more polyphenols than the pulps. 'Bella del Bosco' had the highest amount of polyphenols and antioxidant activity, whereas 'Piatlin' had the lowest phenolic content. All ancient cultivars presented a higher amount of pulp phenolic compounds than 'Golden Delicious'. Immunoblotting techniques showed that 'Bella del Bosco' and 'Piatlin' had very low quantities of Mal d 3 allergen; hence, they can be considered hypoallergenic cultivars.

CONCLUSIONS

The preservation of ancient apple cultivars would be of great importance, not only to maintain the biodiversity but also for their nutritional properties. The hypoallergenic activity of some of these cultivars could be of interest also for the preparation of different apple-based products. © 2020 Society of Chemical Industry.

Genome wide analysis and functional identification of MdKCS genes in apple

Apple fruit is covered by cuticle wax, which plays important roles protecting fruits from adverse environmental conditions. β-Ketoacyl-CoA synthase (KCS) is the key rate-limiting enzyme in plant wax synthesis. In this study, we identified 28 KCS gene family members from apple (Malus × domestica Borkh.) by homology analysis. Multi-sequence alignment and phylogenetic analyses revealed that the 28 MdKCS genes were divided into four subgroups, including KCS1-like, FAE1-like, FDH-like, and CER6. A chromosomal localization analysis revealed that 27 apple KCS genes were located on 11 chromosomes, while MdKCS28 was localized to the unassembled genomic scaffold. Most of the MdKCS proteins were hydrophilic proteins and they had similar secondary and tertiary structures. The prediction of cis-acting elements of the MdKCS gene promoters suggested that the MdKCS genes may be widely involved in hormone signaling and the stress response. Furthermore, the quantitative real-time polymerase chain reaction results showed that eight MdKCS genes were highly expressed in the apple pericarp, and were significantly induced by drought, abscisic acid (ABA), and NaCl treatments. We transformed the MdKCS21 gene into apple calli, and found the MdKCS21 overexpressing transgenic apple calli exhibited higher tolerance to ABA treatment. Finally, the MdKCS proteins were localized to the endoplasmic reticulum and vacuolar membrane by confocal laser microscopy. This study established a foundation to further analyze the function of KCS genes and provided candidate genes for molecular improvement of wax content in apple.

Phenotypic variation of floral organs in Malus using frequency distribution functions

BACKGROUND

Phenotypic diversity of floral organs plays an important role in plant systematic taxonomy and genetic variation studies. Previous research have focused on the direction of variation but disregarded its degree. Phenotypic variation (including directions and degrees) of 17 floral traits from wild to cultivated crabapples were explored by comparing their distributions and deviations in three different dimensions: floral organ number, size, and the shape.

RESULTS

Except for petal number, petal length / petal width, and sepal length / sepal width, the analyzed floral traits of cultivated crabapples all showed downward distributed box bodies in box plot analysis and left deviations of fitted curves in frequency distribution function analysis when compared to the wild, which revealed consistent variation directions of petaloid conversion (pistils or stamens → petals), size miniaturization (large → small), and shape narrowness (petal shape: circular → elliptic; sepal shape: triangular → lanceolate). However, only seven floral traits exhibited significant differences in box plot analysis, while all of the traits in frequency distribution function analysis were obviously offset. The variation degrees were quantitatively characterized by sizing traits > shaping traits > numbering traits and by horizontal dimensions > radial dimensions.

CONCLUSIONS

Frequency distribution function analysis was more sensitive than the box plot analysis, which constructed a theoretical basis for Malus flower type breeding and would provide a new quantitative method for future evaluation of floral variation among different groups of angiosperms at large.

Geographical origin of Chinese apples based on multiple element analysis

BACKGROUND

Apples from different regions of China show different qualities and internal characteristics, and appeal to different customers. However, these aspects have not been studied in depth. We characterized the profiles of 14 elements in 317 apple samples collected from five regions of China. Principal component analysis (PCA), linear discriminant analysis (LDA), and back-propagation artificial neural networks analysis (BP-ANN) were used to build models for apple authentication.

RESULTS

Fourteen elements were successfully identified in apple samples by performing graphite furnace atomic absorption spectrometry (GFAAS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) analyses. Comparative analysis showed significantly different element profiles in samples from different regions. The first five principal components obtained by PCA accounted for 71.8% of the total variance. The LDA obtained 70.0% classification rates. The BP-ANN obtained 82.7% classification rates.

CONCLUSION

This study indicated the possibility that apples could be authenticated based on differences in their element profiles, and provided a basis for further geographical origin studies. © 2019 Society of Chemical Industry.

Gene-Wide Analysis of Aquaporin Gene Family in Malus domestica and Heterologous Expression of the Gene MpPIP2;1 Confers Drought and Salinity Tolerance in Arabidposis thaliana

The aquaporins (AQPs) are a family of integral membrane proteins involved in the transcellular membrane transport of water and other small molecules. A scan of the apple (Malus domestica) genome revealed the presence of 42 genes encoding putative AQPs. Based on a phylogenetic analysis of the deduced peptide sequences of the AQPs generated by Arabidopsis thaliana, poplar (Populus trichocarpa), and rubber (Hevea brasiliensis), the apple AQPs were each assigned membership of the five established AQP subfamilies, namely the PIPs (eleven members), the TIPs (thirteen members), the NIPs (eleven members), the SIPs (five members), and the XIPs (two members). The apple AQPs included asparagine-proline-alanine (NPA) motifs, an aromatic/arginine (ar/R) selectivity filter, and the Froger’s positions. The heterologous expression of MpPIP2;1 in A. thaliana was shown to enhance the level of tolerance exhibited against both drought and salinity.

Non-destructive classification of apple bruising time based on visible and near-infrared hyperspectral imaging

BACKGROUND

Bruising time of apple is one of the most important factors for internal quality assessment. The present study aimed to establish a non-destructive method for the classification of apple bruising time using visible and near-infrared (VNIR) hyperspectral imaging. In this study, VNIR hyperspectral images were obtained and analyzed at seven bruising periods. Moreover, regions of interest (ROIs) were chosen to construct the bruised region classification model, and spectra of bruised regions were collected and resampled based on four different methods. Subsequently, machine learning algorithms were employed and used for dealing with the time classification model of apples. In order to reduce data redundancy and improve the accuracy of the classification model, a tree-based assembling learning model was used to select feature wavelengths, and linear discriminant analysis (LDA) was used to improve the discernibility of data.

RESULTS

The results revealed that the random forest (RF) model can precisely locate bruised regions, while the gradient boosting decision tree (GBDT) model can validly classify apple bruising times with 70.59% accuracy. Data of 128 wavebands were compressed to 13 wavebands, providing a high accuracy of 92.86%.

CONCLUSION

The results prove that the hyperspectral technique can be used for predicting apple bruising time, which will help to assess the internal quality and safety of apples. © 2018 Society of Chemical Industry.

Attachment and colonization of Salmonella on 'Rayada', 'Golden Delicious', and 'Red Delicious' apples

BACKGROUND

Fruits and vegetables have been associated with outbreaks of disease in different countries. The apple (Malus domestica Borkh) and its products have been reported as vehicles for illness outbreaks. To create strategies to prevent pathogen survival it is necessary to understand how pathogens persist on fruit. This paper assessed the ability of Salmonella to attach to, and to colonize, the surface of three apple cultivars: 'Rayada', 'Golden Delicious' and 'Red Delicious'.

RESULTS

Salmonella was able to colonize and generate biofilms on the surface of apples with a soil suspension as the only source of nutrients. Significant differences in Salmonella attachment were seen among the three cultivars of apple studied. Using SEM, attached cells and the formation of exopolysaccharides and biofilms on the three apple cultivars were demonstrated. In all cultivars, the development of Salmonella was only seen in apples stored at 15 and 22 °C, with average increases in the population of 1.4 and 2.3 Log CFU/apple, respectively. At 5 °C, Salmonella growth was inhibited.

CONCLUSION

Salmonella can colonize apple surfaces under environmental conditions (relative humidity, temperature and nutrients) occurring in primary apple production. © 2018 Society of Chemical Industry.

Genome-wide Identification, Classification, Molecular Evolution and Expression Analysis of Malate Dehydrogenases in Apple

Malate dehydrogenase plays crucial roles in energy homeostasis, plant development and cold and salt tolerance, as it mediates the reversible conversion of malate to oxaloacetate. However, the evolutionary pattern of MDH genes in apple remains elusive. In this study, a total of 20 MDH genes were identified from the "Golden Delicious" apple draft genome. We revealed the physiological and biochemical properties, gene structure, and conserved motifs of MdMDH genes. Chromosomal localization and Ka/Ks ratio analysis of MdMDH genes revealed different selective pressures acted on duplicated MdMDH genes. Exploration of the phylogenetic relationships revealed six clades and similar frequencies between old and recent duplications, and significant differences in the evolutionary rates of the MDH gene family were observed. One MdMDH gene, MDP0000807458, which was highly expressed during apple fruit development and flower bud differentiation, was under positive selection. Thus, we speculated that MDP0000807458 is a likely candidate gene involved in regulation of flower bud differentiation and organic acid metabolism in apple fruits. This study provides a foundation for improved understanding of the molecular evolution of MdMDH genes and further facilitates the functional analysis of MDP0000807458 to unravel its exact role in flower bud differentiation and organic acid metabolism.

Can you make morphometrics work when you know the right answer? Pick and mix approaches for apple identification

Morphological classification of living things has challenged science for several centuries and has led to a wide range of objective morphometric approaches in data gathering and analysis. In this paper we explore those methods using apple cultivars, a model biological system in which discrete groups are pre-defined but in which there is a high level of overall morphological similarity. The effectiveness of morphometric techniques in discovering the groups is evaluated using statistical learning tools. No one technique proved optimal in classification on every occasion, linear morphometric techniques slightly out-performing geometric (72.6% accuracy on test set versus 66.7%). The combined use of these techniques with post-hoc knowledge of their individual successes with particular cultivars achieves a notably higher classification accuracy (77.8%). From this we conclude that even with pre-determined discrete categories, a range of approaches is needed where those categories are intrinsically similar to each other, and we raise the question of whether in studies where potentially continuous natural variation is being categorised the level of match between categories is routinely set too high.

Seasonal Variability of the Phytochemical Composition of New Red-Fleshed Apple Varieties Compared with Traditional and New White-Fleshed Varieties

The main objective of this study was to evaluate the impact of the season on the apple phytochemical composition (phenolic compounds, triterpenes, and organic and ascorbic acids). For this proposal, four red-fleshed and five white-fleshed apple varieties from two consecutive seasons (2015 and 2016) were studied. A significant interaction with the season in some compounds was observed. The total phenolic content in the apple flesh from 2015 was higher than that from 2016 probably related with the lower rainfall during the harvest period in 2015 that could have favored hydric stress in the apple trees. The impact of the season on the apple skin was different. The 2016 season was characterized by higher maximum and minimum temperatures resulting in a higher content of flavonols, triterpenes, and organic acids. Anthocyanin concentration in both the flesh and skin of the red-fleshed apples showed no clear relationship to the season, and each variety showed an individual pattern.

Paecilomyces Rot: A New Apple Disease

Paecilomyces niveus is an important food spoilage fungus that survives thermal processing in fruit products, where it produces the mycotoxin patulin. Spoilage of products has been attributed to soil contamination; however, little is known about the ecology of this organism. In this study, orchard soils and culled apple fruit were surveyed and the ability of P. niveus to infect apple was tested on two popular apple varieties. P. niveus was found in 34% of sampled orchard soils from across New York. Completing Koch's postulates, P. niveus was demonstrated to cause postharvest disease in Gala and Golden Delicious apple. Symptoms of this disease, named Paecilomyces rot, resemble several other apple diseases, including black rot, bitter rot, and bull's-eye rot. External symptoms of Paecilomyces rot include brown, circular, concentrically ringed lesions, with an internal rot that is firm and cone-shaped. Both Gala and Golden Delicious apple fruit inoculated with P. niveus developed lesions ≥43 mm in size at 22 days after inoculation. There is some evidence that the size of lesions and rate of infection differ between Gala and Golden Delicious, which may indicate differing resistance to P. niveus. This work shows that P. niveus is common in New York orchard soil and can cause a novel postharvest fruit disease. Whether infected fruit can serve as an overlooked source of inoculum in heat-processed apple products requires further study.

Differentiation of Apple Varieties and Investigation of Organic Status Using Portable Visible Range Reflectance Spectroscopy

Food fraud, the sale of goods that have in some way been mislabelled or tampered with, is an increasing concern, with a number of high profile documented incidents in recent years. These recent incidents and their scope show that there are gaps in the food chain where food authentication methods are not applied or otherwise not sufficient and more accessible detection methods would be beneficial. This paper investigates the utility of affordable and portable visible range spectroscopy hardware with partial least squares discriminant analysis (PLS-DA) when applied to the differentiation of apple types and organic status. This method has the advantage that it is accessible throughout the supply chain, including at the consumer level. Scans were acquired of 132 apples of three types, half of which are organic and the remaining non-organic. The scans were preprocessed with zero correction, normalisation and smoothing. Two tests were used to determine accuracy, the first using 10-fold cross-validation and the second using a test set collected in different ambient conditions. Overall, the system achieved an accuracy of 94% when predicting the type of apple and 66% when predicting the organic status. Additionally, the resulting models were analysed to find the regions of the spectrum that had the most significance. Then, the accuracy when using three-channel information (RGB) is presented and shows the improvement provided by spectroscopic data.

WNT Inhibitory Activity of Malus Pumila miller cv Annurca and Malus domestica cv Limoncella Apple Extracts on Human Colon-Rectal Cells Carrying Familial Adenomatous Polyposis Mutations

Inhibitors of the Wingless-related Integration site (WNT)/β-catenin pathway have recently been under consideration as potential chemopreventive agents against Familial Adenomatous Polyposis (FAP). This autosomal-dominant syndrome is caused by germline mutations in the gene coding for the protein APC and leads to hyperactivation of the WNT/β-catenin signaling pathway, uncontrolled intestinal cell proliferation and formation of adenocarcinomas. The aim of the present work was to: (i) test, on in vitro cultures of cells carrying FAP mutations and on ex vivo biopsies of FAP patients, the WNT inhibitory activity of extracts from two common southern Italian apples, Malus pumila Miller cv. 'Annurca' and Malus domestica cv 'Limoncella'; (ii) identify the mechanisms underpinning their activities and; (iii) evaluate their potency upon gastrointestinal digestion. We here show that both Annurca and Limoncella apple extracts act as WNT inhibitors, mostly thanks to their polyphenolic contents. They inhibit the pathway in colon cells carrying FAP mutations with active dilutions falling in ranges close to consumer-relevant concentrations. Food-grade manufacturing of apple extracts increases their WNT inhibitory activity as result of the conversion of quercetin glycosides into the aglycone quercetin, a potent WNT inhibitor absent in the fresh fruit extract. However, in vitro simulated gastrointestinal digestion severely affected WNT inhibitory activity of apple extracts, as result of a loss of polyphenols. In conclusion, our results show that apple extracts inhibit the WNT pathway in colon cells carrying FAP mutations and represent a potential nutraceutical alternative for the treatment of this pathology. Enteric coating is advisable to preserve the activity of the extracts in the colon-rectal section of the digestive tract.

Genome re-sequencing reveals the history of apple and supports a two-stage model for fruit enlargement

Human selection has reshaped crop genomes. Here we report an apple genome variation map generated through genome sequencing of 117 diverse accessions. A comprehensive model of apple speciation and domestication along the Silk Road is proposed based on evidence from diverse genomic analyses. Cultivated apples likely originate from Malus sieversii in Kazakhstan, followed by intensive introgressions from M. sylvestris. M. sieversii in Xinjiang of China turns out to be an "ancient" isolated ecotype not directly contributing to apple domestication. We have identified selective sweeps underlying quantitative trait loci/genes of important fruit quality traits including fruit texture and flavor, and provide evidences supporting a model of apple fruit size evolution comprising two major events with one occurring prior to domestication and the other during domestication. This study outlines the genetic basis of apple domestication and evolution, and provides valuable information for facilitating marker-assisted breeding and apple improvement.Apple is one of the most important fruit crops. Here, the authors perform deep genome resequencing of 117 diverse accessions and reveal comprehensive models of apple origin, speciation, domestication, and fruit size evolution as well as candidate genes associated with important agronomic traits.

Biochemical Profile of Heritage and Modern Apple Cultivars and Application of Machine Learning Methods To Predict Usage, Age, and Harvest Season

The present study represents the first major attempt to characterize the biochemical profile in different tissues of a large selection of apple cultivars sourced from the United Kingdom's National Fruit Collection comprising dessert, ornamental, cider, and culinary apples. Furthermore, advanced machine learning methods were applied with the objective to identify whether the phenolic and sugar composition of an apple cultivar could be used as a biomarker fingerprint to differentiate between heritage and mainstream commercial cultivars as well as govern the separation among primary usage groups and harvest season. A prediction accuracy of >90% was achieved with the random forest method for all three models. The results highlighted the extraordinary phytochemical potency and unique profile of some heritage, cider, and ornamental apple cultivars, especially in comparison to more mainstream apple cultivars. Therefore, these findings could guide future cultivar selection on the basis of health-promoting phytochemical content.

Phenolic Content and Antioxidant Activity during the Development of 'Brookfield' and 'Mishima' Apples

The aim of this study was to characterize the changes in the contents of total (TPC) and individual (IPC) phenolic compounds, the total antioxidant activity (TAA) in the peel and pulp, and total anthocyanins (TAN) in the peel during the development of the fruits of 'Brookfield' and 'Mishima' apple trees. 'Brookfield' apples were harvested from the 49th to the 138th days after full bloom (DAFB) and 'Mishima' apples from the 45th to the 172th DAFB. In the pulp, the IPC, TPC, and TAA rapidly reduced at 75 and 79 DAFB for the 'Brookfield' and 'Mishima' apples, respectively, and then remained constant until commercial maturity. In the peel of 'Brookfield' apples there was a reduction in the TPC and TAA at 79 DAFB. The quercetin 3-galactoside, epicatechin, and procyanidin B2 contents reduced up to 107 DAFB with a subsequent increase in the values at commercial maturity. In the peel of 'Mishima' apples there was a reduction in the TPC, TAA, epicatechin, and procyanidin B1 and B2 contents at 130 DAFB, with a subsequent increase until commercial maturity. The TAN content in the peel increased during the 2 and 4 weeks prior to commercial maturity for 'Brookfield' and 'Mishima' apples, respectively. In the pulp and peel of both cultivars there was a reduction in the IPC, TPC, and TAA as the development proceeded. On nearing commercial maturity, there was an increase in the contents of quercetin 3-galactoside, epicatechin, procyanidin B2, and TAN in the peel for both cultivars.

McMYB12 Transcription Factors Co-regulate Proanthocyanidin and Anthocyanin Biosynthesis in Malus Crabapple

The flavonoid compounds, proanthocyanidins (PAs), protect plants from biotic stresses, contribute to the taste of many fruits, and are beneficial to human health in the form of dietary antioxidants. In this study, we functionally characterized two Malus crabapple R2R3-MYB transcription factors, McMYB12a and McMYB12b, which co-regulate PAs and anthocyanin biosynthesis. McMYB12a was shown to be mainly responsible for upregulating the expression of anthocyanin biosynthetic genes by binding to their promoters, but to be only partially responsible for regulating PAs biosynthetic genes. In contrast, McMYB12b showed preferential binding to the promoters of PAs biosynthetic genes. Overexpression of McMYB12a and McMYB12b in tobacco (Nicotiana tabacum) altered the expression of flavonoid biosynthetic genes and promoted the accumulation of PAs and anthocyanins in tobacco petals. Conversely, transient silencing their expression in crabapple plants, using a conserved gene region, resulted in reduced PAs and anthocyanin production a green leaf phenotype. Meanwhile, transient overexpression of the two genes and silenced McMYB12s in apple (Malus domestica) fruit had a similar effect as overexpression in tobacco and silenced in crabapple. This study reveals a new mechanism for the coordinated regulation of PAs and anthocyanin accumulation in crabapple leaves, which depends on an auto-regulatory balance involving McMYB12a and McMYB12b expression.

Phytochemical Profiles of New Red-Fleshed Apple Varieties Compared with Traditional and New White-Fleshed Varieties

This study is an exhaustive chemical characterization of the phenolic compounds, triterpenes, and organic and ascorbic acids in red-fleshed apple varieties obtained by different breeding programs and using five traditional and new white-fleshed apple cultivars as reference. To carry out these analyses, solid-liquid extraction (SLE) and ultraperformance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) were used. The results showed that the red-fleshed apples contained, in either the flesh or peel, higher amounts of phenolic acids (chlorogenic acid), anthocyanins (cyanidin-3-O-galactoside), dihydrochalcones (phloretin xylosyl glucoside), and organic acids (malic acid) but a lower amount of flavan-3-ols than the white-fleshed apples. These quantitative differences could be related to an up-regulation of anthocyanins, dihydrochalcones, and malic acid and a down-regulation of flavan-3-ols (anthocyanin precursors) in both the flesh and peel of the red-fleshed apple varieties. The reported results should be considered preliminary because the complete phytochemical characterization of the red-fleshed apple cultivars will be extended to consecutive harvest seasons.

Reduced representation genome sequencing reveals patterns of genetic diversity and selection in apple

Identifying DNA sequence variations is a fundamental step towards deciphering the genetic basis of traits of interest. Here, a total of 20 cultivated and 10 wild apples were genotyped using specific-locus amplified fragment sequencing, and 39,635 single nucleotide polymorphisms with no missing genotypes and evenly distributed along the genome were selected to investigate patterns of genome-wide genetic variations between cultivated and wild apples. Overall, wild apples displayed higher levels of genetic diversity than cultivated apples. Linkage disequilibrium (LD) decays were observed quite rapidly in cultivated and wild apples, with an r² -value below 0.2 at 440 and 280 bp, respectively. Moreover, bidirectional gene flow and different distribution patterns of LD blocks were detected between domesticated and wild apples. Most LD blocks unique to cultivated apples were located within QTL regions controlling fruit quality, thus suggesting that fruit quality had probably undergone selection during apple domestication. The genome of the earliest cultivated apple in China, Nai, was highly similar to that of Malus sieversii, and contained a small portion of genetic material from other wild apple species. This suggested that introgression could have been an important driving force during initial domestication of apple. These findings will facilitate future breeding and genetic dissection of complex traits in apple.

High Triterpenic Acids Production in Callus Cultures from Fruit Pulp of Two Apple Varieties

INTRODUCTION

Very rarely fruit pulp has been used in in vitro culture to produce secondary metabolites useful in promoting health.

OBJECTIVES

The aims of this work were the study of the best conditions to obtain the callus cultures from the pulp of two varieties of apples, Golden Delicious (GD) and "Mela Rosa Marchigiana" (MRM), and the quali-quantitative analysis of secondary metabolites produced by the two in vitro callus cultures.

METHODOLOGY

Callus was induced on both Murashige and Skoog and Gamborg B5 media containing various combinations of supplements. To achieve the maximum recovery of secondary metabolites produced, preliminary extraction tests were carried out on GD apple culture using two different organic solvents (MeOH and EtOAc). The quali-quantitative analysis of the methanolic extract of both cultures was carried out by ESI-MSⁿ and GC-MS techniques.

RESULTS

The GC-MS analysis revealed the presence of triterpenic acids, in particular, oleanolic, ursolic, maslinic, pomolic, tormentic, corosolic and annurcoic acid along with a phytosterol, β-sitosterol. In addition, GD callus culture produced phloridzin, absent in the MRM culture. In this last culture, however, the total amount of secondary metabolites was markedly higher. The in vivo production of these bioactive compounds were also quantified in the GD and MRM apple pulps.

CONCLUSION

Apple pulps produced higher amounts of triterpenic acids in vitro than in vivo. The present work can be considered a method to amplify the production of important secondary metabolites which exert beneficial effects on human health. Copyright © 2016 John Wiley & Sons, Ltd.

Analysis of the genetic diversity and structure across a wide range of germplasm reveals prominent gene flow in apple at the European level

BACKGROUND

The amount and structure of genetic diversity in dessert apple germplasm conserved at a European level is mostly unknown, since all diversity studies conducted in Europe until now have been performed on regional or national collections. Here, we applied a common set of 16 SSR markers to genotype more than 2,400 accessions across 14 collections representing three broad European geographic regions (North + East, West and South) with the aim to analyze the extent, distribution and structure of variation in the apple genetic resources in Europe.

RESULTS

A Bayesian model-based clustering approach showed that diversity was organized in three groups, although these were only moderately differentiated (FST = 0.031). A nested Bayesian clustering approach allowed identification of subgroups which revealed internal patterns of substructure within the groups, allowing a finer delineation of the variation into eight subgroups (FST = 0.044). The first level of stratification revealed an asymmetric division of the germplasm among the three groups, and a clear association was found with the geographical regions of origin of the cultivars. The substructure revealed clear partitioning of genetic groups among countries, but also interesting associations between subgroups and breeding purposes of recent cultivars or particular usage such as cider production. Additional parentage analyses allowed us to identify both putative parents of more than 40 old and/or local cultivars giving interesting insights in the pedigree of some emblematic cultivars.

CONCLUSIONS

The variation found at group and subgroup levels may reflect a combination of historical processes of migration/selection and adaptive factors to diverse agricultural environments that, together with genetic drift, have resulted in extensive genetic variation but limited population structure. The European dessert apple germplasm represents an important source of genetic diversity with a strong historical and patrimonial value. The present work thus constitutes a decisive step in the field of conservation genetics. Moreover, the obtained data can be used for defining a European apple core collection useful for further identification of genomic regions associated with commercially important horticultural traits in apple through genome-wide association studies.

Sugar and phenol content in apple with or without watercore

BACKGROUND

Watercore is a physiological disorder affecting fruit of some apple (Malus domestica Borkh.) cultivars. Intercellular spaces are filled with fluid, which reduces intercellular air space volume. In this study individual phenolic content, sugars and organic acids in watercore affected flesh have been identified and quantified. Peroxidase activity was also measured, as a potential stress indicator. The study was performed on three cultivars prone to watercore development 'Delicious', 'Gloster' and 'Fuji'.

RESULTS

Total phenolic content was higher in flesh of fruit without watercore in all three cultivars, which was mainly due to higher individual and total flavanol content. In contrast, total and individual dihydrochalcone content was higher in watercore flesh, where it was up to 2.4 times higher from the flesh of fruit without watercore. Also, peroxidase activity was higher in watercore flesh.

CONCLUSION

Higher peroxidase activity and total and individual dihydrochalcone content leads us to believe that oxidative stress occurred. These results show that watercore has an influence on apple fruit sugar and phenol content even before any visual signs of internal breakdown and browning. With the development of non-destructive techniques for phenol content determination, the knowledge about phenolic changes in watercore affected fruits could aid with apple fruit sorting. © 2015 Society of Chemical Industry.

Use of descriptive analysis and preference mapping for early-stage assessment of new and established apples

BACKGROUND

This research compared four new apple selections with 16 established apples using descriptive analysis (DA), instrumental analyses and preference mapping, in order to identify suitable selections for commercialization and further research.

RESULTS

DA revealed that the new apple selections (PARC1, PARC2, PARC3, PARC4) were very similar in texture/mouthfeel (T) but differed in their flavor (F) and appearance (A) characteristics. Preference mapping revealed that consumers' T preferences were driven primarily by crispness, juiciness and lack of skin toughness, while F preferences were driven by sweetness, lack of tartness and presence of fruity flavor. Consumers' A preferences were driven by a high percentage of red color and degree of striping. The majority of consumers had similar T (82-85%) and F (88-92%) preferences for the early- and mid/late-harvest apples. In contrast, consumers' A preferences were differentiated into three subgroups (60%, 24%, 16%) for the early-harvest apples, but not for the mid/late-harvest apples. The new apple selections were among those most liked for T, F and A.

CONCLUSION

This early-stage consumer research confirmed that the new apples were comparable, if not superior, to the established apples. As such, it provided the necessary feedback to industry to proceed with commercialization and optimization of cultural and storage practices.

Fast Estimation of Dietary Fiber Content in Apple

Dietary fibers (DF) are one of the nutritional benefits of fleshy fruit consumption that is becoming a quality criterion for genetic selection by breeders. However, the AOAC total DF content determination is not readily amenable for screening large fruit collections. A new screening method of DF content in an apple collection based on the automated preparation of cell wall material as an alcohol-insoluble residue (AIR) is proposed. The yield of AIR from 27 apple genotypes was compared with DF measured according to AOAC method 985.29. Although residual protein content in AIRs did not affect DF measurement, subtraction of starch content above 3% dry weight in AIRs was needed to agree with AOAC measured DF. A fast colorimetric screening of starch in AIR was developed to detect samples needing correction. The proposed method may prove useful for the rapid determination of DF in collections of other fleshy fruit besides apple.

Traceability of different apple varieties by multivariate analysis of isotope ratio mass spectrometry data

RATIONALE

The awareness of customers of the origin of foods has become an important issue. The growing demand for foods that are healthy, safe and of high quality has increased the need for traceability and clear labelling. Thus, this study investigates the capability of C and N stable isotope ratios to determine the geographical origin of several apple varieties grown in northern Italy.

METHODS

Four apple varieties (Cripps Pink, Gala, Golden Delicious, Granny Smith) have been sampled in orchards located in the Districts of Bolzano, Ferrara, Verona and Udine (northern Italy). Carbon (δ(13) C) and nitrogen (δ(15) N) isotope values of the whole apple fruits and three sub-fractions (peel, pulp and seed) have been determined simultaneously by isotope ratio mass spectrometry.

RESULTS

The δ(13) C and δ(15) N values of apples and apple sub-fractions, such as peel, seed and pulp, were significantly affected by the geographical origin and the fruit variety. The four varieties could be distinguished to a certain extent only within each district. A 99% correct identification of the samples according to their origin was, however, achieved by cross validation with the 'leave-one-out' method.

CONCLUSIONS

This study proves the potential of stable isotopes to discriminate the geographical origin of apples grown in orchards located only a few hundreds of kilometres apart. Stable isotopes were also able to discriminate different apple varieties, although only within small geographical areas.

[AFLP Analysis of Genetic Diversity in the Genus Mallus Mill. (Apple)]

The first molecular genetic analysis of the apple species and varieties from Russian collections with the AFLP marker system was performed in order to study the genetic diversity of the genus Malus, as well as to clarify the phylogeny and solve some systematic issues of the genus. Nienty-one apple accessions, including species from five sections of the genus Malus and hybrid species, were examined. The level of polymorphism constituted 90.2%. It was demonstrated that the classical taxonomy of the genus Malus, which identifies five sections based on differences in their morphological characters, is valid and may be used to classify apple species. The species assignment of the Antonovka landraces was established. All of them belonged to the species M. domestica. It was demonstrated that the Yakutskaya apple variety was a domesticated species of the section Gymnomeles, presumably, M. baccata. AFLP analysis confirmed the hybrid nature of many species. The relationships between apple varieties of the Golden group with American wild species were demonstrated. The data suggest that the species M. sieversii was the ancestor of not only the domestic apple but also of other species of the Malus sections.

HPLC-DAD-MS Profiling of Polyphenols Responsible for the Yellow-Orange Color in Apple Juices of Different French Cider Apple Varieties

The pigments responsible for the yellow-orange coloration of apple juices have remained largely unknown up to now. Four French cider apple juices were produced in conditions similar to those used in the cider-making industry. The oxidized juices, characterized using the CIE L a b parameters, displayed various colors depending on the apple variety and native phenolic composition. HPLC-DAD-MS revealed contrasting pigment profiles related to oxidized tanning and nontanning molecules. The latter were divided into two groups according to their polarity and their visible spectra. With regard to phenolic classes, flavanol monomers and hydroxycinnamic acids played an essential role in the formation of oxidation products. Interestingly, dihydrochalcones appeared to include precursors of some yellow compounds. Indeed, the yellow pigment phloretin xyloglucoside oxidation product (PXGOPj), derived from phloretin xyloglucoside, was clearly identified in apple juices as a xyloglucose analogue of the yellow pigment phloridzin oxidation product (POPj), previously characterized in a model solution by Le Guernevé et al. (Tetrahedron Lett. 2004, 45 (35), 6673-6677).

Is there room for improving the nutraceutical composition of apple?

In this study, we assessed the main bioactive compounds of a broad apple germplasm collection, composed by 247 accessions of wild (97) and domesticated (150) species. Among the stilbenes, trans- and cis-piceid were found to be ubiquitary components of both wild and cultivated apples. Apple was suggested to be the second dietary source of resveratrols. Results confirmed that the selection pressure of breeding and domestication did not uniformly affect all the phytochemicals contained in apples. For instance, organic acids (malic and ascorbic acid) and some phenolics (stilbenes, hydroxycinnamic acids, and dihydrochalcones) were significantly influenced by selection, while some relevant flavonoids (flavonols and flavan-3-ols) and triterpenoids (ursolic, oleanolic, and betulinic acids) were not. This comprehensive screening will assist in the selection of Malus accessions with specific nutraceutical traits suitable to establish innovative breeding strategies or to patent new functional foods and beverages.

Volatile profiles of members of the USDA Geneva Malus Core Collection: utility in evaluation of a hypothesized biosynthetic pathway for esters derived from 2-methylbutanoate and 2-methylbutan-1-ol

The volatile ester and alcohol profiles of ripening apple fruit from 184 germplasm lines in the USDA Malus Germplasm Repository at the New York Agricultural Experiment Station in Geneva, NY, USA, were evaluated. Cluster analysis suggested biochemical relationships exist between several ester classes. A strong linkage was revealed between 2-methylbutanoate, propanoate, and butanoate esters, suggesting the influence of the recently proposed "citramalic acid pathway" in apple fruit. Those lines with a high content of esters formed from 2-methylbutan-1-ol and 2-methylbutanoate (2MB) relative to straight-chain (SC) esters (high 2MB/SC ratio) exhibited a marked increase in isoleucine and citramalic acid during ripening, but those lines with a low content did not. Thus, the data were consistent with the existence of the hypothesized citramalic acid pathway and suggest that the Geneva Malus Germplasm Repository, appropriately used, could be helpful in expanding our understanding of mechanisms for fruit volatile synthesis and other aspects of secondary metabolism.

An apple B-box protein, MdCOL11, is involved in UV-B- and temperature-induced anthocyanin biosynthesis

Our studies showed that an apple B-box protein, MdCOL11, the homolog of AtBBX22, is involved in UV-B- and temperature-induced anthocyanin biosynthesis in apple peel. Anthocyanin is responsible for the red pigmentation in apple peel and a R2R3 MYB gene, MdMYBA/1/10, a homolog of MdMYBA, controls its accumulation. Arabidopsis PAP1 is under the control of a series of upstream factors involved in light signal transduction and photomorphogenesis, such as ELONGATED HYPOCOTYL 5 (HY5) and B-box family (BBX) proteins. In this study, we identified and characterized the homolog of Arabidopsis BBX22 in apple, designated as MdCOL11. Overexpression of MdCOL11 in Arabidopsis enhanced the accumulation of anthocyanin. In apples, MdCOL11 was differentially expressed in all tissues, with the highest expression in petals and the lowest expression in the xylem. Transcripts of MdCOL11 noticeably accumulated at the ripening stage, concomitant with increases in the expressions of anthocyanin biosynthesis-related genes. In an in vitro treatment experiment, MdCOL11 was upregulated in an ultra-violet (UV)-B- and temperature-dependent manner, together with the inductions of anthocyanin biosynthesis-related genes and anthocyanin accumulation in apple peel. Furthermore, a dual-luciferase assay indicated that (1) MdCOL11 regulated the expression of MdMYBA and (2) MdCOL11 was a target of MdHY5. Taken together, our results suggest that MdCOL11 is involved in MdHY5-mediated signal transduction and regulates anthocyanin accumulation in apple peel, which sheds new light on anthocyanin accumulation in apples.

Enzymes extracted from apple peels have activity in reducing higher alcohols in Chinese liquors

As the unavoidable byproducts of alcoholic fermentation, higher alcohols are unhealthy compounds widespread in alcoholic drinks. To investigate the activity of apple crude enzymes toward higher alcohols in liquors, five kinds of apple peels, namely, Fuji, Gala, Golden Delicious, Red Star, and Jonagold, were chosen to prepare enzymes, and three kinds of Chinese liquors, namely, Xifeng (containing 45% ethanol), Taibai (containing 50% ethanol), and Erguotou (containing 56% ethanol), were tested. Enzymes were prepared in the forms of liquid solution, powder, and immobilized enzymes using sodium alginate (SA) and chitosan. The treatment was carried out at 37 °C for 1 h. The relative amounts of different alcohols (including ethanol, 1-propanol, isobutanol, 1-butanol, isoamylol, and 1-hexanol) were measured using gas chromatography (GC). Conditions for preparing SA-immobilized Fuji enzymes (SA-IEP) were optimized, and the obtained SA-IEP (containing 0.3 g of enzyme) was continuously used to treat Xifeng liquor eight times, 20 mL per time. Significant degradation rates (DRs) of higher alcohols were observed at different degrees, and it also showed enzyme specificity according to the apple varieties and enzyme preparations. After five repeated treatments, the DRs of the optimized Fuji SA-IEP remained 70% for 1-hexanol and >15% for other higher alcohols.

Bioanalytical characterization of apple juice from 88 grafted and nongrafted apple varieties grown in Upper Austria

The compositional characteristics of untreated pure juice prepared from 88 apple varieties grown in the region of Eferding/Upper Austria were determined. Many of the analyzed varieties are noncommercial, old varieties not present in the market. The aim of the study was to quantitate the mineral, phosphate, trace elements, and polyphenolic content in order to identify varieties that are of particular interest for a wider distribution. Great variations among the investigated varieties could be found. This holds especially true for the total polyphenolic content (TPC) ranging from 103.2 to 2,275.6 mg/L. A clear dependence of the antioxidant capacity on the TPC levels was detected. Bioinformatics was employed to find specific interrelationships, such as Mg²⁺/Mn²⁺ and PO₄³⁻/K⁺, between the analyzed bio- and phytochemical parameters. Furthermore, special attention was drawn on putative effects of grafting on the phytochemical composition of apple varieties. By grafting 27 different apple varieties on two trees grown close to each other, it could be shown that the apple fruits remain their characteristic phytochemical composition. Finally, apple juice prepared from selected varieties was further characterized by additional biochemical analysis including cytotoxicity, epidermal growth factor receptor (EGFR) inhibition, and α-amylase activity tests. Cytotoxicity and inhibition of EGFR activation were found to be dependent on the TPC, while α-amylase activity was reduced by the apple juices independent of the presence of polyphenolic substances. Taken together selected apple varieties investigated within this study might serve as preferable sources for the development of apple-based food with a strong focus on health beneficial effects.

Recent patents on physical, mineral & organic Acid composition of golden delicious and red delicious apples (malus×domestica borkh) grown in the west of Iran

Apple is one of the fruits that has beneficial effects on human healthy diet and life. The aim of this study is to determine some physical, mineral and organic acids composition of apple cultivars grown in different locations throughout Lorestan province. Apple cultivars had been harvested from different locations throughout Lorestan province of Iran. Analyses for 3 elements (Iron, Zinc, and calcium) were conducted by the flame atomic absorption spectrometry. Phosphorus was measured by the UV-Vis spectrophotometer and Sodium and Potassium were measured by the flame photometer. Organic acids were determined by Titration method using NaOH and phenolphethalein indicator. Weight was measured by scale based on 0.1 g and length and diameters were measured by caliper. The mean weight of Red Delicious and Golden Delicious apples was 173.7 g and 146.7 g, respectively. The amount of iron, zinc, calcium, phosphorus, sodium, and potassium for the red variety was 0.24, 0.14, 28, 8.9, 4.7 and 63.8 respectively; values for the Golden variety were 0.23, 0.14, 27.9, 8.8, 4.5, and 66.3 mg/100g fresh weight, respectively. The amount of ascorbic acid, malic acid, and citric acid for Golden delicious was 9.09, 0.27 and 0.28, respectively; for Red delicious apples, the amount was 9.47, 0.26 and 0.28 mg/100 g, respectively. Acidities for Golden delicious and Red delicious were 3.7 and 4, respectively. One hundred gram of apple fruit grown in Lorestan would provide 3% of iron, 1.5% of zinc, 2.8% of calcium and 1.4% of potassium requirements. The amount of organic acid in apples of Lorestan province was lower than some other countries.

A sampling approach for predicting the eating quality of apples using visible-near infrared spectroscopy

BACKGROUND

Visible-near infrared spectroscopy remains a method of increasing interest as a fast alternative for the evaluation of fruit quality. The success of the method is assumed to be achieved by using large sets of samples to produce robust calibration models. In this study we used representative samples of an early and a late season apple cultivar to evaluate model robustness (in terms of prediction ability and error) on the soluble solids content (SSC) and acidity prediction, in the wavelength range 400-1100 nm.

RESULTS

A total of 196 middle-early season and 219 late season apples (Malus domestica Borkh.) cvs 'Aroma' and 'Holsteiner Cox' samples were used to construct spectral models for SSC and acidity. Partial least squares (PLS), ridge regression (RR) and elastic net (EN) models were used to build prediction models. Furthermore, we compared three sub-sample arrangements for forming training and test sets ('smooth fractionator', by date of measurement after harvest and random). Using the 'smooth fractionator' sampling method, fewer spectral bands (26) and elastic net resulted in improved performance for SSC models of 'Aroma' apples, with a coefficient of variation CVSSC = 13%. The model showed consistently low errors and bias (PLS/EN: R(2) cal = 0.60/0.60; SEC = 0.88/0.88°Brix; Biascal = 0.00/0.00; R(2) val = 0.33/0.44; SEP = 1.14/1.03; Biasval = 0.04/0.03). However, the prediction acidity and for SSC (CV = 5%) of the late cultivar 'Holsteiner Cox' produced inferior results as compared with 'Aroma'.

CONCLUSION

It was possible to construct local SSC and acidity calibration models for early season apple cultivars with CVs of SSC and acidity around 10%. The overall model performance of these data sets also depend on the proper selection of training and test sets. The 'smooth fractionator' protocol provided an objective method for obtaining training and test sets that capture the existing variability of the fruit samples for construction of visible-NIR prediction models. The implication is that by using such 'efficient' sampling methods for obtaining an initial sample of fruit that represents the variability of the population and for sub-sampling to form training and test sets it should be possible to use relatively small sample sizes to develop spectral predictions of fruit quality. Using feature selection and elastic net appears to improve the SSC model performance in terms of R(2), RMSECV and RMSEP for 'Aroma' apples.

Additional indications for the low allergenic properties of the apple cultivars Santana and Elise

Patients with Oral Allergy Syndrome (OAS) to fresh apple may tolerate low allergenic apple cultivars. We aimed to investigate if the low allergenic properties of Elise and Santana, as previously identified in a Dutch population, could be generalised within North West Europe within the birch pollen region with regard to both the prevalence and degree of sensitization. Prick-to-prick tests (PTP) were performed in eighty-five adult patients with OAS to fresh apple in Great Britain, Switzerland and Northern Italy, before the birch pollen season, using the putatively low allergenic apple cultivars Elise, Santana, Granny Smith, Modi and Mcintosh, as well as the putatively high allergenic apple cultivars Golden Delicious and Kanzi. No significant differences in percentages of negative responses of PTPs were found between the three countries. Negative responses did not differ from negative responses to the different apple cultivars we previously found in 2006/2007 in the Netherlands. The size of the PTPs of all apple cultivars tested were correlated to the size of the skin prick tests with birch pollen. These results add to the indications for the low allergenic properties of the low allergenic apple cultivars Santana and Elise, as the number of negative responses were reproducible in three countries within the birch pollen region and were similar to previous results in the Netherlands. These results justify oral challenge studies with Elise and Santana within the birch pollen region, to establish the low allergenic properties for the benefit for apple allergic consumers for definite conclusions.

[Analysis of sequences of ITS1 internal transcribed spacer and 5.8S ribosome gene of Malus species]

The nucleotide sequence of the ITS1-5.8S ribosomal DNA spacer fragment was determined for 41 samples of the Malus species. The total length of compared sequences ranged from 389 to 392 bp. The nucleotide sequence of the 5.8S gene within the genus was highly conserved. The level of polymorphism of ITS 1 region comprised 14%. Both species- and group-specific substitutions were identified. The analysis of M. orientalis and M. turkmenorum sequences revealed their full identity, which indicates the need to perform more research with a larger number of samples of both species from other collections to clarify the taxonomic status of the M. turkmenorum species. The previous findings on the synonymy of species M. baccata, M. mandshurica, M. pallasiana, and M. sachalinensis were also confirmed.

Comparison of antioxidant capacity and phenolic composition of peel and flesh of some apple varieties

BACKGROUND

Apples contain a large concentration of phenolic compounds, dependent on factors such as cultivar, harvest, storage conditions, and processing. This study aims to identify the essential phenolic compounds present in various apple varieties, to measure their total antioxidant capacity (TAC) with the CUPRAC (cupric ion reducing antioxidant capacity) and ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate)) methods, and to correlate their TAC values with HPLC findings.

RESULTS

The order of TAC (mmol Trolox g(-1) fresh weight) of apple peels determined with the CUPRAC method was: Granny Smith > Amasya > Sky Spur > Ervin Spur > King Luscious ≥ Arap Kizi ≥ Lutz Golden. The theoretically calculated TAC values of HPLC-quantified compounds, with the aid of the combined HPLC-CUPRAC method, accounted for 18.4-33.5% of the experimentally observed CUPRAC capacity of peel extracts and 19.5-56.3% of flesh extracts, depending on apple variety.

CONCLUSION

In synthetic samples of apple antioxidants, the CUPRAC-TAC values of constituents, identified and analyzed by HPLC, proved to be additive, enabling measurement of the cooperative action of antioxidants using the proposed methodology. Apple peel showed higher contents of phenolics and therefore higher TAC than apple flesh, confirming the health benefit of the consumption of apples together with peel.

Functional genomics reveals that a compact terpene synthase gene family can account for terpene volatile production in apple

Terpenes are specialized plant metabolites that act as attractants to pollinators and as defensive compounds against pathogens and herbivores, but they also play an important role in determining the quality of horticultural food products. We show that the genome of cultivated apple (Malus domestica) contains 55 putative terpene synthase (TPS) genes, of which only 10 are predicted to be functional. This low number of predicted functional TPS genes compared with other plant species was supported by the identification of only eight potentially functional TPS enzymes in apple 'Royal Gala' expressed sequence tag databases, including the previously characterized apple (E,E)-α-farnesene synthase. In planta functional characterization of these TPS enzymes showed that they could account for the majority of terpene volatiles produced in cv Royal Gala, including the sesquiterpenes germacrene-D and (E)-β-caryophyllene, the monoterpenes linalool and α-pinene, and the homoterpene (E)-4,8-dimethyl-1,3,7-nonatriene. Relative expression analysis of the TPS genes indicated that floral and vegetative tissues were the primary sites of terpene production in cv Royal Gala. However, production of cv Royal Gala floral-specific terpenes and TPS genes was observed in the fruit of some heritage apple cultivars. Our results suggest that the apple TPS gene family has been shaped by a combination of ancestral and more recent genome-wide duplication events. The relatively small number of functional enzymes suggests that the remaining terpenes produced in floral and vegetative and fruit tissues are maintained under a positive selective pressure, while the small number of terpenes found in the fruit of modern cultivars may be related to commercial breeding strategies.

Nutraceutical potential of polyphenolic fractions from Annurca apple (M. pumila Miller cv Annurca)

The capacities of polyphenolic extracts from Annurca apple peel and flesh to inhibit the glucose and cholesterol uptake by HepG2 cells were evaluated, and compared with those of other conventional cultivars, such as Red Delicious (RD), Pink Lady (PL), Fuji (F) and Golden Delicious (GD). RD peels exhibited the best hypoglycaemic effects, while Annurca flesh appeared the most active in reducing cell cholesterol uptake among the cultivars tested. The influence of the apple polyphenolic extracts on the cell proliferation and oxidative stress was also evaluated. Particularly, RD, Annurca and PL peels decreased proliferation by a 62.5%, 48.0% and 37.5%, respectively, probably due to their prooxidant capacity. Conversely, flesh extracts appeared more protective of cells than peels: Annurca and RD, particularly, proved to be able of increasing proliferation by a 32.2% and 11.1%, respectively, probably due to their capacity of reducing cell physiological radical levels of a 33.3% and 19.9%, respectively.

Analysis of cellulose synthase genes from domesticated apple identifies collinear genes WDR53 and CesA8A: partial co-expression, bicistronic mRNA, and alternative splicing of CESA8A

Cellulose synthase (CesA) genes constitute a complex multigene family with six major phylogenetic clades in angiosperms. The recently sequenced genome of domestic apple, Malus×domestica, was mined for CesA genes, by blasting full-length cellulose synthase protein (CESA) sequences annotated in the apple genome against protein databases from the plant models Arabidopsis thaliana and Populus trichocarpa. Thirteen genes belonging to the six angiosperm CesA clades and coding for proteins with conserved residues typical of processive glycosyltransferases from family 2 were detected. Based on their phylogenetic relationship to Arabidopsis CESAs, as well as expression patterns, a nomenclature is proposed to facilitate further studies. Examination of their genomic organization revealed that MdCesA8-A is closely linked and co-oriented with WDR53, a gene coding for a WD40 repeat protein. The WDR53 and CesA8 genes display conserved collinearity in dicots and are partially co-expressed in the apple xylem. Interestingly, the presence of a bicistronic WDR53-CesA8A transcript was detected in phytoplasma-infected phloem tissues of apple. The bicistronic transcript contains a spliced intergenic sequence that is predicted to fold into hairpin structures typical of internal ribosome entry sites, suggesting its potential cap-independent translation. Surprisingly, the CesA8A cistron is alternatively spliced and lacks the zinc-binding domain. The possible roles of WDR53 and the alternatively spliced CESA8 variant during cellulose biosynthesis in M.×domestica are discussed.

Developmental variation of phenolic compounds in fruit tissue of two apple cultivars

BACKGROUND

Qualitative and quantitative analyses of 'Zonouz' and 'Gala' apples phenolic compounds were accomplished by HPLC.

MATERIAL AND METHODS

Samples for phenolics study were taken at three different growing stages [1 - fruit early growing stage 2 - mid-stage of fruit development (80 days after full bloom) 3 - during commercial harvest time].

RESULTS

The results showed qualitative differences between two apple cultivars regarding phenolic compounds. The highest amounts of total phenols, flavonoids, flavonols and phenolic acids content in both cultivars were recorded during the fruit early growing stage. The high phenolic acids content was due to increasing in chlorogenic acid content in fruits during early growing stage. The highest amount for flavanol content was recorded in 'Zonouz' peel at the harvest time. Descending pattern was recorded for phloridzin dihydrate content during the season. 'Gala' peel had the greatest amounts for cyanidin-3-galactoside at harvest time. Increasing in total flavonoid content was due to the great amounts of cyanidine-3-galactoside and epicatechin (in 'Gala' peel), rutin hydrate (in 'Zonouz' pulp) at fruit early growing stage, catechin (in 'Zonouz' peel) during mid-stage of fruit development and cyanidin-3-galactoside and quercetin-3-D-galactoside (in 'Gala' peel) at the harvest time in both apple cultivars.

CONCLUSIONS

There were meaningful quantitative differences between two cultivars, and 'Gala' was richer in phenolics than 'Zonouz'.

Non-destructive evaluation of ripening and quality traits in apples using a multiparametric fluorescence sensor

BACKGROUND

The detection of pigments and colourless flavonoids in apples can provide a useful indication of fruit quality. Optical methods are preferable because they are fast and non-destructive. In this study, a fluorescence-based portable sensor was used in order to non-invasively determine the content of chlorophylls, anthocyanins and flavonols in Fuji, Granny Smith and Golden Delicious apple cultivars. The aim was to define new non-destructive optical indices of apple quality.

RESULTS

The anthocyanin index (ANTH) in Fuji was higher in the sunny (i.e. sun-exposed) side of the fruit compared to the shady side. For all cultivars, the flavonol index (FLAV) was higher in the sunny side compared with the shady side. The chlorophyll index (CHL) for the shady sides of Granny Smith and Golden Delicious was significantly higher than for the sunny sides. Fine linear regressions were found between the ANTH, FLAV and CHL indices and the actual anthocyanin, flavonol and chlorophyll concentrations, respectively, which were determined destructively on the apple peel extracts. A negative correlation was found between the apple sugar content and the chlorophyll fluorescence in the far-red spectral band.

CONCLUSION

Our results indicate that a single multiparametric fluorescence-based sensor can provide valuable non-destructive markers of ripening and quality in apples.