Apple Genotypes Research Articles

Juices, Fibres and Skin Waste Extracts from White, Pink or Red-Fleshed Apple Genotypes as Potential Food Ingredients

This study measures and compares the bioactive content and appearance attributes of juices, dietary fibres (DFs) and skin wastes of three apple genotypes (white fleshed (WF), pink fleshed (PF) and red fleshed (RF)). The juices of the PF and RF apples had more appealing and stable colours and much greater total extractable polyphenol content (TEPC) (RF had the highest, 3.40 mg catechin equivalent/mL juice) and vitamin C (PF had the highest, 14.2 mg/100 mL juice), compared with the WF apple. DFs isolated from the three apples using aqueous and ethanolic methods varied in bioactive profiles as a function of genotype. The TEPC and antioxidant activity (AA) of the fibres decreased in the order of PF > RF > WF. The total DF (TDF) in the fibre obtained using the aqueous method decreased in the order of RF > PF > WF. The ethanolic method yielded higher neutral monosaccharide (NM) and slightly greater TDF contents than the aqueous method. More polyphenol species were detected in the PF fibres, especially those obtained using the aqueous method. The polyphenol content in the apple skin decreased in the order of RF > WF > PF, with PF having slightly more pectic polysaccharides. As a whole, the RF apple appeared to be the best genotype as the potential source for juice, fibre and skin waste extract (SWE) ingredients. The PF apple would be the second best genotype for juice and fibre ingredients. The skin of the RF and WF genotypes would provide a good source of polyphenols. There is potential for promoting RF and PF apple genotypes because of their excellent nutritional values. The aqueous fibre preparation method used herein containing no solvent treatment and freezing steps represents an industrial-scale cost-effective alternative to the conventional ethanolic methods used for producing DFs whilst retaining polyphenols.

Levels of fire blight (Erwinia amylovora) susceptibility of native apple, pear and quince germplasm from Lake Van Basin, Turkey

Fire blight resistance of apple, pear and quince genetic resources from Lake Van Basin (eastern Turkey) was tested using Erwinia amylovora strain Ea Van. Shoot tips of 92 native accessions (48 accessions for apple, 38 accessions for pear and 6 accessions for quince) were wounded for inoculation, and artificially inoculated with pathogenic bacteria under greenhouse conditions. The levels of resistance of accessions were classified in comparison with control varieties according to the genotype susceptibility index (GSI%) scores based on the lesion length on shoots of each genotype. Fire blight resistance of accessions consisted of five classes: resistant (R), moderately resistant (MR), moderately susceptible (MS), susceptible (S) and highly susceptible (HS). GSI% scores differed significantly among accessions from each fruit species (p < 0.01). GSI values ranged from 12.4% to 64.1% for apple genotypes, from 17.2% to 55.1% for pear genotypes, and from 17.8% to 43.4% for quince genotypes. No resistant genotypes of apple, pear and quince were observed. Seven accessions of apple, two accessions of pear and one accession of quince were MR. 25 accessions of apple, 14 accessions of pear and one accession of quince were MS. These findings indicate a considerable variation in fire blight resistance and could contribute to breeding efforts regarding fire blight resistance in apple, pear and quince.

Examination of expansin genes as related to apple fruit crispness

The possible relationship of seven expansin genes to maintenance of apple (Malus × domestica Borkh.) crispness during storage was examined. Expression of expansin genes MdEXPA1, MdEXPA2, MdEXPA3, MdEXPA4, MdEXPA5, and MdEXPA7 was quantified among apple cultivars that remained crisp or lost crispness between harvest and after 8 weeks of cold storage. MdEXPA1 was expressed in low quantities in fresh fruit while expression of MdEXPA4, MdEXPA5, and MdEXPA7 was not detected among fresh or cold-stored apple cultivars. Among the expansin isoforms studied, MdEXPA2 and MdEXPA3 were the most abundantly expressed. A new expansin isoform, with homology to PcEXPA1 and low expression levels in fresh and cold-stored apples, was isolated in this study and designated MdEXPA8. Two alleles of MdEXPA2 were identified with different 3′UTR sequences, and 41 apple genotypes were allelotyped for MdEXPA2 gene to determine to what extent a relationship existed between allelotype and loss of fruit crispness. Paired t tests suggested that there was no relationship between allelotype and crispness maintenance. However, genotype sample size was small and may have been inadequate to detect any effect. The gene for 1-aminocyclopropane 1-carboxylate synthase, MdACS1, was also allelotyped in the 41 apple genotypes to determine if there might be an additive effect with MdEXPA2 allelotype and was found to be unsuitable as a marker for maintenance of apple fruit crispness for the crosses used in this study. Furthermore, fragment analyses showed that MdEXPA2 allelotype had no effect on transcript stability, and protein blots suggested no effect on translation.

Molecular Mechanisms of Pathogenesis and Resistance to the Bacterial Pathogen Erwinia amylovora, Causal Agent of Fire Blight Disease in Rosaceae

Fire blight, caused by the necrogenic Gram-negative bacterium Erwinia amylovora, is one of the most destructive bacterial diseases of apple (Malus × domestica) and pear (Pyrus communis), among other members of the Rosaceae family. This disease poses a major economic threat to pome production as there are no available effective control measures. Genetic enhancement of fire blight resistance in apples is the best alternative for averting disease damage, loss of crop, and loss of whole trees. In this review, current knowledge of the molecular mechanisms of E. amylovora pathogenesis will be presented, especially those of effector proteins during bacterial–host interactions, as well as assessment of current understanding of the molecular controls of plant host resistance. Recent studies are elucidating how type III effectors modulate plant susceptibility and promote growth and dissemination of the pathogen. The large multidomain protein DspE is essential for E. amylovora pathogenesis and plays an additional role(s) in inhibiting salicylic acid-mediated innate immunity. On the other hand, the apple host defends itself against E. amylovora invasion by relying on quantitative resistance genes that likely respond to and/or complex with E. amylovora effectors. Thus far, a total of 27 quantitative trait loci (QTL) linked to fire blight resistance have been identified in different apple genetic backgrounds and in response to different E. amylovora strains. In addition to quantitative genetic approaches, microarray analysis of E. amylovora-challenged apple genotypes identified differential transcriptional expression in susceptible and resistant apples. Mechanisms of bacterial pathogenicity and plant host resistance offer intriguing scenarios as to how effector proteins in E. amylovora interact with groups of genes for resistance in the apple host, particularly when considering that these quantitative genes have small effects in plant defense against the invading bacterial pathogen. This collective knowledge will provide insights into bacterial pathogenesis and plant host resistance, as well as highlight implications and opportunities for developing fire blight-resistant apple cultivars.

Thermal time requirements for phenophases of apple genotypes in Kullu valley

A field experiment was conducted at Horticultural Research Station, Seobag (Kullu) from 2004 to 2010. The phenology of ten apple cultivars was observed on every second day on three plants of each cultivar with three replications from bud-bust, green-tip, pink-bud, full-bloom to physiological maturity. GDD, HTU, PTU, HYTU and heat use efficiency was computed from the meteorological data recorded from observatory and averaged of for ten years. Tydeman, commercial and Mollice has taken lower GDD for the physiological maturity but higher for attaining petal-fall. On an average apple required 330 GDD from bud bust to petal fall with 4oC as base temperature. Cultivars completing the rest period earlier used more thermal units and giving good fruit yields as compare to those breaking their dormancy later. Thermal units explain more than 75-99 % variation in fruit yield. Higher thermal use efficiency was observed for Starking Delicious and Vance Delicious followed by Top Red and Tydeman which may be encouraged among the growers.

The constitutive phenolic composition of two Malus × domestica genotypes is not responsible for their contrasted susceptibilities to fire blight

Apple ( Malus × domestica) leaf phenolics, in particular the three major dihydrochalcones, phloridzin, trilobatin and sieboldin, were studied for their potential contribution to the resistance to Erwinia amylovora, the causative agent of fire blight. The constitutive phenolic compositions of part of a progeny resulting from a cross between two apple genotypes, displaying contrasted susceptibilities to fire blight, were investigated by RP–HPLC–DAD. With regards to the major dihydrochalcones, offsprings were found to display the parent profile: either phloridzin alone or a combination of phloridzin, trilobatin and sieboldin. Despite a strong antioxidant activity that could interfere with the oxidative burst triggered by the bacteria, sieboldin did not segregate with resistance even though it was strongly associated with a high constitutive antioxidant capacity of leaf extracts. Several hydroxycinnamic acids and flavonols were identified in the progeny but profiles were very similar. However, concentrations of several flavonols positively correlated with resistance in the genotypes that possessed trilobatin and sieboldin. The major dihydrochalcones that represent more than 200 mg/g of leaf DW are not directly responsible for resistance to fire blight in this system. In addition, a high constitutive antioxidant activity is unlikely to be sufficient to block bacterial spread.

Gene Expression is Highly Regulated in Early Developing Fruit of Apple

An oligonucleotide-based microarray for apple was developed consisting of ~40,000 sequences, along with positive and negative controls, obtained from 34 cDNA libraries constructed from both vegetative and reproductive tissues at different stages of development, varying genotypes, and under different biotic and abiotic stresses. This apple microarray was used to investigate global gene expression profiles in early developing fruit of three apple genotypes, including “Golden Delicious”, “Gala”, and “Fuji”. A set of 3,348 genes, exhibiting significant differential expression profiles among the three different genotypes, was identified. This set primarily included genes encoding enzymes involved in metabolism and genes related to cell cycle. Differentially expressed genes were grouped into 17 functional categories. Quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR) confirmed differential expression for most genes detected in the microarray analysis, particularly those involved in cell division, cell expansion, and cell enlargement. Among those genes investigated, EF-1 alpha and PRP exhibited differential expression in different apple genotypes and demonstrated a regulatory role during early fruit development. Moreover, a total of 12 differentially expressed genes were identified during early fruit development in three genotypes of apple. These included genes encoding for aminotransferase family protein, DnaJ heat shock, histone, rubisco activase, and tetratricopeptide (TPR) repeat containing protein. This genome-wide analysis suggested that genes engaged in early fruit development among different genotypes of apple are highly regulated.

The threat of wild habitat to scab resistant apple cultivars

Evaluations of plant resistance to pathogens are rarely made using isolates from wild habitats, although the heterogeneity of such habitats may generate pathogen diversity which could be a source of new virulence in cultivated habitats. The aim of this study was to investigate whether scab resistance factors, identified and characterized in apples using isolates of Venturia inaequalis from a cultivated habitat, remained effective against isolates from a wild habitat. Three V. inaequalis core collections originating from the cultivated apple Malus × domestica and from two wild species, M. sieversii and M. sylvestris, were established to maximize pathogen diversity. For each core collection, 10 isolates were inoculated in mixtures onto 51 genotypes from an apple progeny segregating for two qualitative resistance genes and six quantitative resistance loci (QRL). On each apple genotype, isolates that contributed to the scab symptoms were identified within the mixture using microsatellite markers. The most frequently detected isolates were inoculated singly to compare their aggressiveness according to their host origin. The results showed that isolates from a wild habitat were able to infect the susceptible apple genotypes. However, these isolates were never more aggressive than isolates from the cultivated habitat on the resistance factors tested. It can therefore be concluded that the resistance factors used in this study, identified with V. inaequalis isolates from a cultivated habitat, remained effective against isolates from M. sylvestris and M. sieversii.

Molecular characterisation and similarity relationships among 48 native and commercial Iranian apple (Malus domestica Borkh.) genotypes using simple sequence repeat (SSR) markers

SummaryIn this study, genetic diversity among 48 Iranian apple genotypes was determined using simple sequence repeat (SSR) markers. Sixty-six alleles were generated at 15 SSR loci. The mean number of alleles per locus was 4.4. A similarity matrix based on Jaccard’s coefficients for all 48 apple genotypes gave values from 0.02 – 0.68, which indicated a broad genetic base. The maximum similarity (0.68) was observed between the genotypes ‘Shahrood’ and ‘M2’. The lowest similarity (0.02) was observed between the genotypes ‘Azayesh’ and ‘Shemiran’. Based on a principal co-ordinates analysis and an unweighted pair-group method using arithmetic average (UPGMA) clustering algorithm, three distinct groups were established. The local genotype, ‘Gami-Almasi’, which was the most dwarf Iranian native apple rootstock, was placed in a separate cluster with a low level of similarity to both other groups.

S-RNase genotypes of apple (Malus domestica Borkh.) including new cultivars, lineages, and triploid progenies

SummaryWe have determined the S-RNase genotypes of 33 new apple cultivars and lineages produced in Japan, 44 unknown cultivars and two lineages, and 22 triploid progenies. We have speculated on the putative parentage of new cultivars and lineages based on their S-RNase genotypes and also identified mistaken parents. In the case of the triploid progenies, the breeding of new cultivars using a triploid paternal parent may pose problems due to its low pollen viability. Nevertheless, diploid and triploid progenies were obtained using a triploid maternal parent. We have compiled a database of 516 apple S-RNase genotypes, including those previously investigated, which included a survey system for cultivar combinations, showing those that were fully-incompatible, semi-compatible, or fully-compatible, together with information on the PCR-RFLP method used for the identification of S-RNase genotypes and S-RNase allele designation (available at http://www.agr.nagoya-u.ac.jp/~0hort/apple/).

Seleção preliminar de genótipos de pinheira em Bom Jesus-PI

The sugar apple (Annona squamosa L.) is native to tropical America, occurring spontaneously in Northeastern Brazil, where it is exploited mainly as subsistence without adequate management and without genetic material selection. An experiment was developed aiming to evaluate yield, physical and chemical characteristics of the fruits of ten sugar apple genotypes in Bom Jesus, Piaui State, Brazil. A completely randomized design with treatments represented by ten genotypes and three replications was adopted. The following variables were evaluated: vitamin C, titratable acidity, soluble solids, SS/TA ratio, longitudinal diameter and transverse, LD/TD, number of seeds per fruit, fruit weight and fruit production per plant. The genotypes were grouped into seven groups, with emphasis on the group III (Gen-02) and group IV (Gen-05), what explicited the differences among sugar apple genotypes studied in relation to the chemical, physical and fruit production. Genotypes GEN-01 and GEN-02 present potential for installation in commercial crops, due to its fruit production, even as natural sources of vitamin C.

Tree and Fruit Characteristics of Various Apple Genotypes Obtained through Mutagenesis

Apple seeds treated with variable intensity doses of irradiation produce alterations of apple heredity, which are generally characterized by the reduction of tree vigour, change of fructification type, crop capacity, fruit shape, colour and biochemical fruit content. Morphological and productive features of trees derived through mutagenesis and fruit quality were studied on twelve apple genotypes, using Jonathan and Golden Delicious cultivars as control. The analysis of apple genotypes growing potential obtained through mutagenesis showed that there were significant differences in the tree height, trunk diameter, crown diameter and fructification type among the apple trees. Several genotypes (G-1/7, G-1/8, G-3/123, G-4/131, G-9/11) were registered with a high content of total nitrogen and protein in the fruits and G-9/11 genotype had the highest content of phosphorus (0.408%). Genotypes G-4/101 and G-4/131 accumulated a high quantity of nitrates, over the maximum admitted levels of 60 ppm NO3- for fresh fruits. Cu and Zn contents were low, under the maximum admitted limits.

Genetic analysis of Turkish apple germplasm using peroxidase gene-based markers

Plant peroxidases belong to a multigene family and posses highly conserved domains allowing to design oligonucleotide primers to amplify DNA sequences coding for peroxidases from plants with unsequenced genomes. Peroxidase gene-based polymorphism among Malus species, and correlation between peroxidase markers were deduced in this study. Turkish apple germplasm was evaluated using 14 peroxidase specific primers. Targeted-PCR amplification of genomic DNA from 192 apple genotypes available in the Turkish genetic resources yielded polymorphisms giving a similarity range from 0.56 to 0.98 with a mean of 0.77. Based on the POGP gene polymorphism, two distinct clusters were detected among the apple accessions, suggesting different evolutionary pathway. Correlation estimates as an indication of linkage disequilibrium between POGP markers ranged from −0.22 to 0.90, suggesting that few POGP markers were clustered and the remaining POGP markers evenly distributed throughout the apple genome. These results demonstrate that primers targeting the peroxidase gene family can be used to study genotypic diversity and evolutionary relationships on an intra- and inter-specific basis.

Evaluation of apple genotypes and Malus species for resistance to Alternaria blotch caused by Alternaria alternata apple pathotype using detached‐leaf method

With 3 figures and 4 tables AbstractAlternaria blotch, caused by Alternaria alternata apple pathotype, is an economically important disease of apple (Malus × domestica Borkh.). Information on the resistance level of apple cultivars to Alternaria blotch is the key to a strategy for integrated control of the disease, however, such information on new apples recently released or on scab‐resistant apples is lacking. The aim of this study was to develop an advanced technique, which allowed one a reliable assessment of apples for resistance to Alternaria blotch, and to evaluate resistance levels of various apple genotypes, especially scab‐resistant apples. Detached‐leaves, youngest opened leaf (leaf 1), second (leaf 2), third (leaf 3), fourth (leaf 4) and fifth (leaf 5) at shoot tip removed from growing shoots of four cultivars, were inoculated with conidial suspension of A. alternata apple pathotype, and the responses were rated at 48‐hour postinoculation; a modified six‐class disease scale was established for the rating system of Alternaria blotch. Leaf 1–3 were suitable for the evaluation and discrimination of resistance level of apple genotypes to the disease. Reliability of assessment was demonstrated in successive 3‐year inoculation tests with detached‐leaves of leaf 2 on 16 cultivated apples; incidence of the disease caused by natural infection of A. alternata at a field was well correlated with the resistance levels determined by the detached‐leaf method among 11 apples. Two‐year inoculations using detached‐leaf method on 41 apple genotypes revealed that 17 scab‐resistant apples, ‘Freedom’, ‘Orlovim’, ‘Orlovski Pioner, ‘Pervinka, ‘R12740‐7A’, ‘Regrindis’, ‘Antonovka’, ‘Dayton’, ‘Florina‐Querina’, ‘Galarina’, ‘Liberty’, ‘Redfree’, ‘Reanda’, ‘Remo’, ‘Priam’, ‘Regine’ and ‘Priscilla’, showed no visible symptoms and were regarded as resistant (R) to A. alternata apple pathotype. In addition to the above genotypes, five scab‐resistant genotypes, ‘GoldRush’, ‘Prima’, ‘Renora’, ‘Rewena’ and ‘Retina’, showed pit‐type small spots on a few inoculated leaves and were also included in this category of resistance level. Three scab‐resistant genotypes, ‘Jonafree’, ‘Reka’ and ‘Co‐op 25,’ exhibited extended necrotic lesions in the inoculated leaves and were regarded as susceptible (S) to the disease. Among 38 cultivated apples and selections of Japanese origin, 27 genotypes were R; ‘Kitaro’, ‘Kotaro’, ‘Santaro’, ‘Chinatsu’, ‘Shinano Sweet’, ‘Shinano Red’, ‘Shinano Gold’, ‘Aori 13’, ‘Akibae’, were included in this category, seven genotypes were S; ‘Beninomai’, ‘Natsumidori’ and several selections were included in S category, and the remaining four genotypes were moderately resistant. Parentage information clearly indicated that source of the susceptibility in the cultivated apples and selections developed in Japan were ‘Delicious’ or ‘Indo’. In contrast to the genotypic differences for levels of resistance to A. alternata apple pathotype in cultivated apples, all Malus spp. tested exhibited complete resistance to A. alternata.

Genetic transformation of apple (Malus x domestica) without use of a selectable marker gene

Selectable marker genes are widely used for the efficient transformation of crop plants. In most cases, antibiotic or herbicide resistance marker genes are preferred because they tend to be most efficient. Due mainly to consumer and grower concerns, considerable effort is being put into developing strategies (site-specific recombination, homologous recombination, transposition, and cotransformation) to eliminate the marker gene from the nuclear or chloroplast genome after selection. For the commercialization of genetically transformed plants, use of a completely marker-free technology would be desirable, since there would be no involvement of antibiotic resistance genes or other marker genes with negative connotations for the public. With this goal in mind, a technique for apple transformation was developed without use of any selectable marker. Transformation of the apple genotype “M.26” with the constructs pPin2Att35SGUSintron and pPin2MpNPR1 was achieved. In different experiments, 22.0–25.4% of regenerants showed integration of the gene of interest. Southern analysis in some transformed lines confirmed the integration of one copy of the gene. Some of these transformed lines have been propagated and used to determine the uniformity of transformed tissues in the plantlets. The majority of the lines are uniformly transformed plants, although some lines are chimeric, as also occurs with the conventional transformation procedure using a selectable marker gene. A second genotype of apple, “Galaxy,” was also transformed with the same constructs, with a transformation efficiency of 13%.

How transgenic and classically bred apple genotypes affect non‐target organisms on higher trophic levels

AbstractCurrent plant breeding comprises classical techniques as well as biotechnological methods suitable to insert target genes into the plant genome. Potential non‐target effects of these newly developed plants have to be evaluated in appropriate risk assessment studies. We investigated non‐target effects of four apple genotypes (Malus × domestica L. Borkh.; Rosaceae). They were either susceptible or resistant to the fungal phytopathogen causing apple scab, Venturia inaequalis (Cke.) Wint. (Ascomycotina: Pleosporales), and were either of transgenic origin or classically bred, differing in or sharing a single trait each. Experiments on insect performance were carried out with two non‐target species, namely the apple leafminer Phyllonorycter blancardella Fabricius (Lepidoptera: Gracillariidae) and its parasitoid Pholetesor circumscriptus Nees (Hymenoptera: Braconidae). Development time of the apple leafminer was not affected by the four apple genotypes. By contrast, the number of emerged adult moths significantly differed between the two classically bred cultivars, whereas no effect of the two transgenic apple genotypes was detected. Paralleling the observations of the apple leafminer development, no impact of the four apple genotypes on parasitoid development time and parasitism success could be detected. Although mean numbers of emerged parasitoids were lower on the cultivars with fewer emerged apple leafminers, these differences were not significant. Herbivore and parasitoid performance was not altered in the presence of pathogen inoculation. In conclusion, host plant suitability was found to be more determined by variability among classically bred apple cultivars than by the transgenic genotypes tested. To elucidate possible effects of transgenic plants within multitrophic interactions, an appropriate risk assessment incorporating the relevant controls is crucial.

Identification of genes differentially expressed during interaction of resistant and susceptible apple cultivars (Malus x domestica) with Erwinia amylovora.

BackgroundThe necrogenic enterobacterium, Erwinia amylovora is the causal agent of the fire blight (FB) disease in many Rosaceaespecies, including apple and pear. During the infection process, the bacteria induce an oxidative stress response with kinetics similar to those induced in an incompatible bacteria-plant interaction. No resistance mechanism to E. amylovora in host plants has yet been characterized, recent work has identified some molecular events which occur in resistant and/or susceptible host interaction with E. amylovora: In order to understand the mechanisms that characterize responses to FB, differentially expressed genes were identified by cDNA-AFLP analysis in resistant and susceptible apple genotypes after inoculation with E. amylovora.ResultscDNA were isolated from M.26 (susceptible) and G.41 (resistant) apple tissues collected 2 h and 48 h after challenge with a virulent E. amylovora strain or mock (buffer) inoculated. To identify differentially expressed transcripts, electrophoretic banding patterns were obtained from cDNAs. In the AFLP experiments, M.26 and G.41 showed different patterns of expression, including genes specifically induced, not induced, or repressed by E. amylovora. In total, 190 ESTs differentially expressed between M.26 and G.41 were identified using 42 pairs of AFLP primers. cDNA-AFLP analysis of global EST expression in a resistant and a susceptible apple genotype identified different major classes of genes. EST sequencing data showed that genes linked to resistance, encoding proteins involved in recognition, signaling, defense and apoptosis, were modulated by E. amylovora in its host plant. The expression time course of some of these ESTs selected via a bioinformatic analysis has been characterized.ConclusionThese data are being used to develop hypotheses of resistance or susceptibility mechanisms in Malus to E. amylovora and provide an initial categorization of genes possibly involved in recognition events, early signaling responses the subsequent development of resistance or susceptibility. These data also provided potential candidates for improving apple resistance to fire blight either by marker-assisted selection or genetic engineering.

Red-fleshed apple as a source for functional beverages

The potential of anthocyanin pigments in fruits and vegetables to provide protection against oxidative damage is well known. Cyanidin-3-O-galactoside is a naturally occurring red pigment commonly found in skin of apples but also present in flesh of certain crab apple and apple genotypes. The purpose of this study was to investigate the cyanidin-3-O-galactoside concentration and antioxidant capacity of juice made from 14 genotypes of red-fleshed apples in comparison to three white-fleshed apple cultivars and three commercial apple juices. Cyanidin-3-O-galactoside was found only in the juice made from red-fleshed apple genotypes with the highest concentrations (39 mg L-1) in a crab apple Roberts Crab. The antioxidant capacity measured using the Folin-Ciocalteu, the ferric reducing antioxidant power (FRAP), and the oxygen radical absorbance capacity (ORAC) assays were the greatest in juice prepared from the red-fleshed genotypes Babine and Malus pumila Niedzwetzkyana, a red-fleshed crab apple genotype. The antioxidant capacity measures were strongly correlated with each other; however, there was no correlation between the concentration of cyanidin-3-O-galactoside and the antioxidant capacity measures. The juice quality parameters °Brix and titratable acidity values were not significantly different among the juices made from the red-fleshed apples, commercial apples and commercial apple juice products.Key words: Red-fleshed apple, Malus species, antioxidants, cyanidin-3-O-galactoside, Folin-Ciocalteu, FRAP, ORAC, functional beverage

Phenolic Profiles and Antioxidant Properties of Apple Skin Extracts

Lipid oxidation, especially the oxidation of polyunsaturated fatty acids, is a significant issue in the food industry impacting both food quality and health of consumers. Apple skin was investigated as a source of natural antioxidants. The phenolic compound composition and antioxidant properties of 21 selected apple genotypes were evaluated. The lipid stabilizing ability of the apple skin extracts was examined using an aqueous emulsion system of methyl linolenate. The total phenolic concentrations determined by high-performance liquid chromatography tandem mass spectrometry of methanolic extracts of skins of the apple genotypes varied from 150 to 700 mg/100 g DW. The antioxidant capacity measured by Folin-Ciocalteu (16.2 to 34.1 mg GAE/100 g DW), ferric reducing antioxidant power (1.3 to 3.3 g TE/100 g DW), oxygen radical absorbance capacity (5.2 to 14.2 g TE/100 g DW), and percent inhibition of oxidation of methyl linolenate (73.8% to 97.2%) varied among the apple genotypes. The apple skin extracts, specifically the crab apple varieties such as "Dolgo," were revealed to be effective inhibitors of oxidation of polyunsaturated fatty acid in a model system and thus can be considered as a potential source of natural food antioxidants.

Heritability and Genetic and Phenotypic Correlations of Apple (Malus×domestica) Fruit Volatiles in a Genetically Diverse Breeding Population

Flavor is an important quality trait of fruit and a target for improvement through plant breeding. Eighty-nine flavor volatiles from 240 apple (Malus domestica) genotypes from a highly diverse breeding population were measured by headspace gas chromatography-mass spectrometry (GC-MS) over 2 years. Heritabilities and phenotypic and genetic correlations were calculated for 23 flavor volatiles. Genetic correlations showed coinheritance of five groups of volatiles, ethyl esters, alcohols and alpha-farnesene, propyl and butyl esters, propanoate and 2-methylbutanoate esters, and acetate esters, consistent with our knowledge of volatile biosynthesis in apple. This work demonstrates a genetic structure underlying the highly variable volatile profiles observed for apple fruit and the potential of GC-MS volatile profiling for the genetic analysis of aroma volatiles in genetically diverse populations.