Geschmack- und gesundheitsrelevante Qualität von ökologisch angbauten Äpfeln: Eine 3jährige Feldvergleichsstudie mit standard- und ganzheitlichen Untersuchungsmethoden

In a 3 years lasting field study with the ‘Golden Delicious’ cultivar, we compared fruits of 5 pairs of organic/integrated fruit farms. The orchards were similar in microclimate, soil conditions and planting system. To assess inner fruit quality we investigated at the beginning and at the end of cold storage: (i) standard parameters (firmness, sugar, malic acid., mineral content); (ii) sensorial quality by panel tests; (iii) health related components (23 phenolic compounds, nutritional fibres; vitamins); and (v) fruit «vitality quality» by holistic approaches (crystallisation in copper chloride, self degradation tests, feeding preference tests with laboratory rats). The most significant differences were found in year one of the study, and were by tendency confirmed in the following two years. In year one all fruit samples of organic orchards had significantly firmer fruit flesh (14%), a 10 % higher index of inner quality (on basis of sugar and malic acid content and fruit flesh firmness), and 15% higher taste scores than conventional ones. Phosphorus content of the fruit flesh was 31% higher in organic apples and closely correlated (r2 = 0.93) with the index of inner quality and sensory score (r2 = 0.69). No extraction method of Phosphorus in the soil (water, NH4-EDTA, citric acid, CAL) correlated with the P-content in the fruits. However, P in the fruit flesh correlated by r2 = 0.72 with the microbial activity of the soil expressed as the ratio of microbialbound Nitrogen and Carbon in the soil. With a value of 3.85 the Cmic:Nmic ratio was 44.5 % lower (thus more favourable) in organic tree strips. Flavanols, with 65.7 % of the total polyphenol content were the dominant group of polyphenols. The content of flavonols was 22.7 % higher in organic apples in the first year and 15.6 % in the average of the three years. The self-degradation test didn't provide significant differences. Laboratory rats, showed a tendency to prefer IP apples probably due to their advanced ripeness. Thus rat behaviour did not correspond with the sensory panel judgement. The picture forming method provided a correct reproducibility with repeated blind samples before and after storage (r2 = 0.83), and distinguished 100 % correctly organic an IP fruit in the first year. In the second year there was one miss qualification. The average value over three dates of the index for «vitality quality», which was especially created for this study, was 44.6 % higher with organic apples The picture forming methods correlated well with sensory scores and standard quality (r2 = 0.63) in the first year. The study revealed interesting and consumer-relevant differences between organic and integrated apples with standard and holistic methods

SENSORY AND HEALTH-RELATED FRUIT QUALITY OF ORGANIC APPLES. A COMPARATIVE FIELD STUDY OVER THREE YEARS USING CONVENTIONAL AND HOLISTIC METHODS TO ASSESS FRUIT QUALITY

In a 3 years lasting field study with the ‘Golden Delicious’ cultivar, we compared fruits of 5 pairs of organic/integrated fruit farms. The orchards were similar in microclimate, soil conditions and planting system. To assess inner fruit quality we investigated at the beginning and at the end of cold storage: (i) standard parameters (firmness, sugar, malic acid., mineral content); (ii) sensorial quality by panel tests; (iii) health related components (23 phenolic compounds, nutritional fibres; vitamins); and (v) fruit «vitality quality» by holistic approaches (crystallisation in copper chloride, self degradation tests, feeding preference tests with laboratory rats). The most significant differences were found in year one of the study, and were by tendency confirmed in the following two years. In year one all fruit samples of organic orchards had significantly firmer fruit flesh (14%), a 10 % higher index of inner quality (on basis of sugar and malic acid content and fruit flesh firmness), and 15% higher taste scores than conventional ones. Phosphorus content of the fruit flesh was 31% higher in organic apples and closely correlated (r2 = 0.93) with the index of inner quality and sensory score (r2 = 0.69). No extraction method of Phosphorus in the soil (water, NH4-EDTA, citric acid, CAL) correlated with the P-content in the fruits. However, P in the fruit flesh correlated by r2 = 0.72 with the microbial activity of the soil expressed as the ratio of microbialbound Nitrogen and Carbon in the soil. With a value of 3.85 the Cmic:Nmic ratio was 44.5 % lower (thus more favourable) in organic tree strips. Flavanols, with 65.7 % of the total polyphenol content were the dominant group of polyphenols. The content of flavonols was 22.7 % higher in organic apples in the first year and 15.6 % in the average of the three years. The self-degradation test didn't provide significant differences. Laboratory rats, showed a tendency to prefer IP apples probably due to their advanced ripeness. Thus rat behaviour did not correspond with the sensory panel judgement. The picture forming method provided a correct reproducibility with repeated blind samples before and after storage (r2 = 0.83), and distinguished 100 % correctly organic an IP fruit in the first year. In the second year there was one miss qualification. The average value over three dates of the index for «vitality quality», which was especially created for this study, was 44.6 % higher with organic apples The picture forming methods correlated well with sensory scores and standard quality (r2 = 0.63) in the first year. The study revealed interesting and consumer-relevant differences between organic and integrated apples with standard and holistic methods

RNA-Mediated Gene Silencing Signals Are Not Graft Transmissible from the Rootstock to the Scion in Greenhouse-Grown Apple Plants Malus sp.

RNA silencing describes the sequence specific degradation of RNA targets. Silencing is a non-cell autonomous event that is graft transmissible in different plant species. The present study is the first report on systemic acquired dsRNA-mediated gene silencing of transgenic and endogenous gene sequences in a woody plant like apple. Transgenic apple plants overexpressing a hairpin gene construct of the gusA reporter gene were produced. These plants were used as rootstocks and grafted with scions of the gusA overexpressing transgenic apple clone T355. After grafting, we observed a reduction of the gusA gene expression in T355 scions in vitro, but not in T355 scions grown in the greenhouse. Similar results were obtained after silencing of the endogenous Mdans gene in apple that is responsible for anthocyanin biosynthesis. Subsequently, we performed grafting experiments with Mdans silenced rootstocks and red leaf scions of TNR31-35 in order to evaluate graft transmitted silencing of the endogenous Mdans. The results obtained suggested a graft transmission of silencing signals in in vitro shoots. In contrast, no graft transmission of dsRNA-mediated gene silencing signals was detectable in greenhouse-grown plants and in plants grown in an insect protection tent

Comparison of the Phenolics Profiles of Forced and Unforced Chicory (Cichorium intybus L.) Cultivars

Modern and sustainable production of safe and healthy high quality vegetables for human consumption is nowadays the goal of many producers. Chicory (Cichorium intybus L.) has become an important crop used as food in many countries over the past decade. In this work field and glasshouse trials were conducted to compare phenolic profiles of hydroponically forced leaves and leaves produced as common agronomic practice of five chicory cultivars. Total phenolic content of hydroponically forced samples ranged from 60 to 140 mg/100 g fresh weight, and those of unforced grown leaves varied between 117 and 386 mg/100 g fresh weight. Red cultivar ‘Treviso’ shows the highest phenolic content for both, unforced and forced leaves extracts. In the unforced leaves a total of 33 and in those of forced a total of 44 compounds (peaks) were used for the discrimination study

Transgenic apple plants overexpressing the - gene of show increased levels of 3-hydroxyphloridzin and reduced susceptibility to apple scab and fire blight

Main conclusion Overexpression of chalcone-3-hydroxylase provokes increased accumulation of 3-hydroxyphloridzin inMalus. Decreased flavonoid concentrations but unchanged flavonoid class composition were observed. The increased 3-hydroxyphlorizin contents correlate well with reduced susceptibility to fire blight and scab. The involvement of dihydrochalcones in the apple defence mechanism against pathogens is discussed but unknown biosynthetic steps in their formation hamper studies on their physiological relevance. The formation of 3-hydroxyphloretin is one of the gaps in the pathway. Polyphenol oxidases and cytochrome P450 dependent enzymes could be involved. Hydroxylation of phloretin in position 3 has high similarity to the B-ring hydroxylation of flavonoids catalysed by the well-known flavonoid 3′-hydroxylase (F3′H). Using recombinant F3′H and chalcone 3-hydroxylase (CH3H) from Cosmos sulphureus we show that F3′H and CH3H accept phloretin to some extent but higher conversion rates are obtained with CH3H. To test whether CH3H catalyzes the hydroxylation of dihydrochalcones in planta and if this could be of physiological relevance, we created transgenic apple trees harbouring CH3H from C. sulphureus. The three transgenic lines obtained showed lower polyphenol concentrations but no shift between the main polyphenol classes dihydrochalcones, flavonols, hydroxycinnamic acids and flavan 3-ols. Increase of 3-hydroxyphloridzin within the dihydrochalcones and of epicatechin/catechin within soluble flavan 3-ols were observed. Decreased activity of dihydroflavonol 4-reductase and chalcone synthase/chalcone isomerase could partially explain the lower polyphenol concentrations. In comparison to the parent line, the transgenic CH3H-lines showed a lower disease susceptibility to fire blight and apple scab that correlated with the increased 3-hydroxyphlorizin contents

Phenolic compounds in juices of apple cultivars and their relation to antioxidant activity

Apples and their juices are important sources of phenolic compounds in human diet. Using the same juice processing method, we compared phenolic composition as well as antioxidant activity of juices from various table apple cultivars, grown at the same location. Antioxidant activity of apple juices was estimated by application of two assays, ABTS cation radical decolorization and by scavenging of reactive oxygen species (ROS) generated by xanthine/xanthine oxidase (O2·-, H2O2, OH·; superoxide assisted Fenton reaction), as measured by inhibition of ethylene release from KMB (α-Keto-γ-(methylthio)butyric acid). The apple juices differed in phenolic content and antioxidant activity, where cultivar differences were more relevant than environmental factors. Furthermore, to improve antioxidant performance in the XOD-test, a juice low in phenol content was supplemented with the appropriate amounts of phenols to the level of the best juice indicating that these phenolics contribute to the antioxidant activity of the apple juice. In ac­cordance to literature, the phenolic compounds re­presenting the main anti­oxidant activity in the apple juices comprise flavan-3-ols and chlorogenic acid.

Phenolic contents in fruit juices of plums with different skin colors

Polyphenols in fruits are of increasing interest for consumers and for plant scientists because of their health beneficial potential and their role in plant physiology and disease resistance. Anthocyanins contribute significantly to the attractive pigmentation of red and blue plums. Mirabelles and several reineclaudes do usually not accumulate anthocyanins in the skin. Is this linked to a general low phenolic level? Both the health aspect and the pigmentation are interesting traits for the breeder. For this purpose, rapid analytical methods are necessary. One time consuming step is the extraction of polyphenols. However, fruit juices are easily produced and are anyhow used for estimation of quality traits such as sugars and acidity. Here we show that HPLC analysis of plum juices represent the phenolic profiles of the whole fruits. We analysed the phenolic patterns of juices from 43 plum varieties with yellow, blue and dark blue fruit skins. In most cases, a weak red pigmentation co-occurs with a low total phenol level. However, there are exceptions that may help the breeder to combine yellow fruit skin with a high level of health beneficial phenolic compounds by using the appropriate donor genotypes. The method described here offers a valuable tool for selection

Flavanols in the nuclei of the tea bush (<i>Camellia sinensis</i>) - broadening the perspectives to human health

Flavanols as a small subclass of the flavonoids stain selectively blue with the special reagent p-dimethylaminocinnamaldehyde (DMACA). Because of the prominent blue colour it is easy to recognize the flavanols histochemically in the vacuoles of expanding and maturing cells. However, the cells of the tea shrub (Camellia sinensis L.) show those blue coloured flavanols also in the nuclei. Silenced interphase nuclei of mature parenchyma cells indicate a pronounced diffuse distribution of blue stained flavanols. By contrast, in activated nuclei the flavanols reflect a variable, mosaic-like blue patterning enclosed by white interchromatin spaces. Subnuclear expression of euchromatin displays relative tiny blue dots of flavanols as compared with the larger-sized blobs of heterochromatin. From metaphase to telophase, the chromosomes stain a fairly dark blue with a more or less diffuse appearance. Those nuclei running through mitotic interphases from G 1 to G 2 have well-defined flavanol-free nucleoli. The flavanol pattern of meristematic chromosomes found in the tea plant is basically also valid for herbaceous plants, such as Hyacinthus romanus, Tulipa gesneriana and Allium cepa, which genuinely do not contain nuclear flavanols. This was verified by incubation of their rootlets in solutions of green tea and epigallocatechin gallate (EGCG). Also human nuclei demonstrate an easy import of added flavanols and the resulting blue stained chromatin reflects in much the same way the structural modifications as already described for the plant nuclei. Possible roles of flavanols in organizing basic mechanisms of chromatin remodelling are discussed. Hereby, also the overall problem of easy oxidizable flavanols should be integrated. Flavanols have the potential to associate to the histone proteins of chromatin. Even small fragments of histones can aggregate to catechin as shown on the basis of kinetic measurements for the H4-core peptide HAKRKT and its acetylated product HAK(ac)RK(ac)T according to the epigenetic histone code

Phenolic compounds in young developing kiwifruit in relation to light exposure: Implications for fruit calcium accumulation

The interaction between light availability and the biosynthesis of phenolic compounds in fruit of kiwifruit (Actinidia deliciosa var. deliciosa, C.F. Liang et A. R. Ferguson) was investigated. Fruits were exposed either to natural light or were artificially shaded while growing on mature vines and were analysed weekly during the first 11 weeks of development. Phenols were identified and quantified by using High Performance Liquid Chromatography (HPLC). Results showed that the predominant phenolic compounds were hydroxycinnamic acids (HCAs), flavonols and the flavan 3-ol epicatechin. Calcium (Ca2+), the main mineral nutrient involved in fruit quality was also determined. Light significantly increased the accumulation of both phenols and Ca2+ into the fruit. This work expands the list of known phenolics in kiwifruit and provides a possible explanation for the seasonal pattern of Ca2+ import into the fruit. Results on light–phenol interaction being apparently beneficial for fruit Ca2+ accumulation, suggest that accurate canopy management could enhance fruit quality