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

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

Ganzheitliche Untersuchungsmethoden zur Erfassung und Prüfung der Qualität ökologischer Lebensmittel: Stand der Entwicklung und Validierung

In dem wachsenden Markt ökologischer Lebensmittel werden Methoden zur produktorientierten Qualitätserfassung gefordert. Dabei geht es u.a. um die Unterscheidung von Produkten aus unterschiedlichen Anbauverfahren. Die Ziele des Projektes waren daher: 1. ausgewählte ganzheitliche Methoden gemäß ISO 17025 zu validieren, d.h. Laborprozesse festzulegen, sowie Einflussgrößen und Verfahrensmerkmale zu bestimmen, 2. zu testen, ob diese Verfahren eine Differenzierung von definierten Proben statistisch abgesichert zeigen können. . Diese Ziele konnten erreicht werden. Es wurde bestätigt, dass einige der Methoden auf Grundlage dokumentierter Prozeduren Lebensmittel aus definierten Anbauversuchen (u.a. aus dem DOK-Versuch am FIBL/CH) reproduzierbar unterscheiden können. Die Koordination und die Validierung der Kupferchlorid-Kristallisation sowie die Messung der Polyphenole lag bei der Universität Kassel, FG Ökologische Lebensmittelqualität und Ernährungskultur. Die KWALIS GmbH, Dipperz, validierte die Fluoreszenz-Anregungsspektroskopie und die Bestimmung des Physiologischen Aminosäurestatus, die EQC GmbH, Weidenbach die elektrochemischen Messungen. Dr. Kromidas, Saarbrücken übernahm die Beratung der Validierungsprozeduren. . An Blindproben wurde untersucht, ob die Verfahren für Weizen- und Möhrenproben aus definierten Anbau- und Sortenversuchen geeignet sind (Fragestellung der Validierung). Die Proben wurden von unabhängiger Stelle (OEL-FAL, Trenthorst) codiert. Die Proben wurden gleichzeitig an alle Partner versandt; dadurch konnten die Methoden auch untereinander verglichen werden. Die Methoden Kupferchlorid-Kristallisation, Fluoreszenz-Anregungsspektroskopie und Physiologischer Aminosäurestatus sind für die Fragestellung geeignet. Mit allen drei Methoden konnten die Proben differenziert und gruppiert werden. Darüber hinaus konnten mit der Fluoreszenz-Anregungsspektroskopie und über den physiologischen Aminosäurestatus die Proben auch den Anbauweisen richtig zugeordnet werden. Allerdings ist damit noch keine Aussage über die Fähigkeit dieser Verfahren möglich, generell Proben aus ökologischer und konventioneller Herkunft zu unterscheiden. Dafür sind weitere Untersuchungen sowohl an Proben definierter Herkunft als auch an Marktproben notwendig

Flavanols in grapevine: In vitro accumulation and defence reactions in shoots

Callus of two grapevine cultivars was cultivated for 4 weeks on MS-medium, half strength, which was additionally supplemented with abscisic acid (ABA), (+)-catechin or a combination of both. (+)-Catechin did not elevate the pool size of the callus flavanols. Application of 3 % sucrose caused a significant increase of the callus flavanols, whereas the response to ABA was quite variable. Leaves and shoots of cv. Spatburgunder (Pinot noir) were examined histologically on the mode of flavanol deposition. The flavanols of the leaf mesophyll were spread evenly throughout the central vacuole whereas those of the outer shoot cortex were confined to special intravacuolar globules. The amorphous leaf flavanols were converted into globdar ones in the vicinity of fungal infections. Apparently, the central vacuole acquires special adjustment under the influence of infection stress. When paraquat was applied to the shoots, amorphous material was attached towards the cell walls. Additionally, the globular flavanols disappeared which could be reversed by addition of (+)-catechin. Thus, (+)-catechin diminished the oxidative damage caused by the oxygen radical producing herbicide. (+)-Catechin and epicatechin are the dominant flavanols of the leaves, whereas the dimeric proanthocyanidins B3 and B1 (PAs) predominate in the callus

Growth enhancement of grapevine call us by catechin on auxin-free media

Proliferating Spätburgunder cells cultured in vitro were found to synthesize the monomeric and oligomeric flavanols catechin, C2, B3, B1, B2 prodelphinidin, ECG (epicatechin gallate), B2G, B2-gallate and B5. Catechin and prodelphinidin were the predominating compounds of all calli studied. Growth promotion of calli from Spatburgunder and Romulus was studied using MS media containing benzyladenine (BA) alone (control), BA plus catechin, and BA combined with two different concentrations of indole-3-acetic acid (IAA). Growth on BA alone was notably reduced. Catechin (68 µM) stimulated callus growth several-fold when combined with 0.8 µM BA; however, this effect was only observed with explants excised from internodes of vigorously growing young shoots

Preliminary studies on the use of the Cascade Rolling Circle Amplification technique for Plum pox virus detection

Isothermal techniques for the amplification of nucleic acids have emerged in the last years. In contrast to the Polymerase chain reaction (PCR), the most prevalent method to amplify DNA in vitro, the reactions can be run at constant temperatures. Specificity and sensitivity are at least as high as that obtained by using PCR and the methods are less time consuming. Therefore, the isothermal amplification of nucleic acids provides a powerful tool for the detection of Plum pox virus (PPV), the causal agent of the Sharka disease. The cascade rolling circle amplification (CRCA), first described by Thomas et al. (1999), is based on the rolling circle mechanism that many viruses use to replicate their genome multiplicatively. Circular Probes, also called Padlock probes (PLP), which arise from the ligation of the terminal region of DNA probes upon side by side hybridization to the target serve as template (Nilsson et al. 1994).For detecting PPV by CRCA, RNA was extracted and reverse transcribed to cDNA using a PPV specific primer. Several PLPs with varying lengths and sequences complementary region to the cDNA were designed and tested. Furthermore, different pairs of primers for the subsequent amplification were developed. For specific ligation Ampligase and T4 DNA Ligase were tested. In CRCA, two polymerases with strong strand displacement activity were compared: Phi29 DNA Polymerase and Bst DNA Polymerase. These enzymes differ in their optimal reaction temperature.Ligation as well as amplification do occur, but there is high background amplification also in negative and no template controls. Discrimination was possible after a restriction digestion is carried out. As proven by sequencing of reaction products non-specific signals were a result of primer polymerization. Current work focuses on the reduction of the background amplification and improvement of the sensitivity. Keywords: Cascade Rolling Circle Amplification, CRCA, isothermal amplification of DNA, Plum pox virus, PP

The inheritance of the hypersensitivity resistance of European plum (Prunus domestica L.) against the Plum pox virus

In between 2003 and 2009 more than 500 seedlings have been tested for hypersensitivity resistance against the Plum pox virus (PPV), which causes Sharka disease. The seedlings had at least one hypersensitive parent genotype. They were tested for hypersensitivity resistance by double grafting onto PPV infected interstem in the green house. In crossing combinations with two hypersensitive parents the percentage of hypersensitive seedlings was highest. There is also no equal distribution of the genotypes over the individual hypersensitivity classes (HC) in all crossing combinations. The percentage of hypersensitive seedlings strongly depends on the parentage. Furthermore investigations regarding the origin of the hypersensitivity resistance of the cultivar ‘Jojo’, which is a descendant of a crossing combination from ‘Ortenauer’ × ‘Stanley’, were done. It was shown that the cultivar ‘Ortenauer’ is the donor of the hypersensitivity trait.Keywords: Plum pox virus, hypersensitivity, inheritance, Prunus domestica L., resistanc

Preliminary studies on the use of the Cascade Rolling Circle Amplification technique for Plum pox virus detection

Isothermal techniques for the amplification of nucleic acids have emerged in the last years. In contrast to the Polymerase chain reaction (PCR), the most prevalent method to amplify DNA in vitro, the reactions can be run at constant temperatures. Specificity and sensitivity are at least as high as that obtained by using PCR and the methods are less time consuming. Therefore, the isothermal amplification of nucleic acids provides a powerful tool for the detection of Plum pox virus (PPV), the causal agent of the Sharka disease. The cascade rolling circle amplification (CRCA), first described by Thomas et al. (1999), is based on the rolling circle mechanism that many viruses use to replicate their genome multiplicatively. Circular Probes, also called Padlock probes (PLP), which arise from the ligation of the terminal region of DNA probes upon side by side hybridization to the target serve as template (Nilsson et al. 1994). For detecting PPV by CRCA, RNA was extracted and reverse transcribed to cDNA using a PPV specific primer. Several PLPs with varying lengths and sequences complementary region to the cDNA were designed and tested. Furthermore, different pairs of primers for the subsequent amplification were developed. For specific ligation Ampligase and T4 DNA Ligase were tested. In CRCA, two polymerases with strong strand displacement activity were compared: Phi29 DNA Polymerase and Bst DNA Polymerase. These enzymes differ in their optimal reaction temperature. Ligation as well as amplification do occur, but there is high background amplification also in negative and no template controls. Discrimination was possible after a restriction digestion is carried out. As proven by sequencing of reaction products non-specific signals were a result of primer polymerization. Current work focuses on the reduction of the background amplification and improvement of the sensitivity