European Journal of Horticultural Science, Apr 20, 2009
As part of a research project 13 cultivars were planted in 2005 at 11 sites in 5 different Austri... more As part of a research project 13 cultivars were planted in 2005 at 11 sites in 5 different Austrian regions. The aim was to find new cultivars tolerant to the soil-borne pathogen Verticillium dahliae and to leaf/fruit diseases, with high yield and good fruit quality, to serve as alternative to 'Elsanta', a highly susceptible cultivar regarding soil-borne diseases. Infestation with V. dahliae was evaluated in 2005 and 2006 at 7 sites and in 2007 at 3 sites. Moreover marketable yield, percentage of different categories of unmarketable fruits, plant vigour, and incidence of the blossom weevil Anthonomus rubi, of chlorosis and of leaf spot diseases were assessed on 2 of the sites in 2006 and 2007. 'Elsanta' showed the highest infestation with V. dahliae whereas 'Salsa' and 'Daroyal' were most tolerant. 'Daroyal', 'Queen Elisa', 'Eva' and 'Dora' showed very high plant vigour. 'Dora', 'Eva', 'Queen Elisa' and 'Daroyal' recorded significantly higher losses by the blossom weevil than 'Alice'. Highest marketable yield per plant had the late ripening cultivars, particularly 'Salsa' and 'Sonata'. Of all early ripening cultivars tested, 'Darselect' showed the highest yield, followed by 'Elsanta', 'Daroyal' and 'Alba'. Summing up all the results, 'Alba', 'Alice', 'Daroyal', 'Darselect' and 'Salsa' can be recommended for organic production. 'Elsanta' and 'Sonata' had high yield under organic farming conditions, but are highly susceptible to V. dahliae. 'Salsa', 'Daroyal', 'Alice', 'Record' and 'Queen Elisa' are suitable for growing in Verticillium-infested soils. As new alternatives to 'Elsanta', the early ripening cultivars 'Alba', 'Clery', 'Daroyal' and 'Queen Elisa' can be used, though 'Clery' and 'Queen Elisa' had rather low yield under organic farming conditions and 'Alba' and 'Clery' are only partially tolerant to V. dahliae. 'Divine' and 'Dora' had low yield and are susceptible to Verticillium-wilt and 'Record' is prone to grey mould. These cultivars cannot be recommended for organic production.
Soil-borne pathogens, above all Verticillium sp. cause plant losses and yield decreases in many A... more Soil-borne pathogens, above all Verticillium sp. cause plant losses and yield decreases in many Austrian strawberry fields, also in organic farming systems; in a research project possibilities to resolve this problem were examined. In a field trial, which was started 1998, organically managed and differently fertilized plots (green compost, manure, hornchips) were compared to an unfertilised control plot and to two mineral fertilized and conventionally treated plots; the differences in field characteristics of strawberries in 2004 and 2005 were low, but differences in storage and biochemical characteristics could be seen in 2005. Some new cultivars tested as alternative to the very sensitive 'Elsanta' planted in 2005 on several farms showed a higher tolerance to diseases and good yield and fruit quality characteristics. Brassica sp. planted as an intercrop before strawberries reduced the amount of microsclerotia of Verticillium dahliae in highly infested soils, nevertheless the system has to be optimised and adapted to our climatic and husbandry conditions in further trials.
As part of a research project 13 cultivars were planted in 2005 at 11 sites on 9 farms in 5 diffe... more As part of a research project 13 cultivars were planted in 2005 at 11 sites on 9 farms in 5 different Austrian regions. The aim was to find new cultivars tolerant to soil-borne pathogens and leaf/fruit diseases, with high yield, winter hardness and good fruit quality, to serve as alternative to the highly susceptible cultivar 'Elsanta', regarding soil-borne diseases. Plant vigour and infestation with Verticillium dahliae and leaf diseases were evaluated in 2005 und 2006 at 7 sites and in 2007 at 3 sites. In addition, following parameters were assessed on 2 organically managed sites in 2006 and 2007: marketable yield, percentage of different categories of unmarketable fruits and incidence of the blossom weevil. In 2006 fruit characteristics and consumer acceptance were studied. 'Elsanta' showed the highest infestation with V. dahliae whereas 'Salsa', 'Daroyal' and 'Alice' were most tolerant. 'Dora', 'Eva', 'Queen Elisa' and 'Daroyal' recorded significantly higher losses by the blossom weevil than 'Alice'. 'Alba' and 'Divine' were the earliest cultivars in ripening time. Highest marketable yield per plant had the late ripening cultivars, particularly 'Salsa' and 'Sonata'.
Soil-borne pathogens, above all Verticillium sp. cause plant losses and yield decreases in many A... more Soil-borne pathogens, above all Verticillium sp. cause plant losses and yield decreases in many Austrian strawberry fields, also in organic farming systems; in a research project possibilities to resolve this problem were examined. In a field trial, which was started 1998, organically managed and differently fertilized plots (green compost, manure, hornchips) were compared to an unfertilised control plot and to two mineral fertilized and conventionally treated plots; the differences in field characteristics of strawberries in 2004 and 2005 were low, but differences in storage and biochemical characteristics could be seen in 2005. Some new cultivars tested as alternative to the very sensitive 'Elsanta' planted in 2005 on several farms showed a higher tolerance to diseases and good yield and fruit quality characteristics. Brassica sp. planted as an intercrop before strawberries reduced the amount of microsclerotia of Verticillium dahliae in highly infested soils, nevertheless the system has to be optimised and adapted to our climatic and husbandry conditions in further trials.
Malus × domestica (apple) accumulates particularly high amounts of dihydrochalcones in various ti... more Malus × domestica (apple) accumulates particularly high amounts of dihydrochalcones in various tissues, with phloridzin (phloretin 2 -O-glucoside) being prevalent, although small amounts of 3-hydroxyphloretin and 3-hydroxyphloridzin are also constitutively present. The latter was shown to correlate with increased disease resistance of transgenic M. × domestica plants. Two types of enzymes could be involved in 3-hydroxylation of dihydrochalcones: polyphenol oxidases or the flavonoid 3 -hydroxylase (F3 H), which catalyzes B-ring hydroxylation of flavonoids. We isolated two F3 H cDNA clones from apple leaves and tested recombinant Malus F3 Hs for their substrate specificity. From the two isolated cDNA clones, only F3 HII encoded a functionally active enzyme. In the F3 HI sequence, we identified two putatively relevant amino acids that were exchanged in comparison to that of a previously published F3 HI. Site directed mutagenesis, which exchanged an isoleucine into methionine in position 211 restored the functional activity, which is probably because it is located in an area involved in interaction with the substrate. In contrast to high activity with various flavonoid substrates, the recombinant enzymes did not accept phloretin under assay conditions, making an involvement in the dihydrochalcone biosynthesis unlikely.
Bidens ferulifolia is a yellow flowering plant, originating from Mexico, which is increasingly po... more Bidens ferulifolia is a yellow flowering plant, originating from Mexico, which is increasingly popular as an ornamental plant. In the past few years, new colour combinations ranging from pure yellow over yellow-red, white-red, pure white and purple have emerged on the market. We analysed 16 Bidens ferulifolia genotypes to provide insight into the (bio)chemical base underlying the colour formation, which involves flavonoids, anthochlors and carotenoids. In all but purple and white genotypes, anthochlors were the prevalent pigments, primarily derivatives of okanin, a 6 -deoxychalcone carrying an unusual 2 3 4 -hydroxylation pattern in ring A. The presence of a cytochrome-P450-dependent monooxygenase introducing the additional hydroxyl group in position 3 of both isoliquiritigenin and butein was demonstrated for the first time. All genotypes accumulate considerable amounts of the flavone luteolin. Red and purple genotypes additionally accumulate cyanidin-type anthocyanins. Acyanic genotypes lack flavanone 3-hydroxylase and/or dihydroflavonol 4-reductase activity, which creates a bottleneck in the anthocyanin pathway. The carotenoid spectrum was analysed in two Bidens genotypes and showed strong variation between the two cultivars. In comparison to anthochlors, carotenoids were present in much lower concentrations. Carotenoid monoesters, as well as diesters, were determined for the first time in B. ferulifolia flower extracts.
ABSTRACT In 2004 and 2005, strawberries (cultivar Elsanta) were tested under different management... more ABSTRACT In 2004 and 2005, strawberries (cultivar Elsanta) were tested under different management systems in a field trial to find out if different fertilizing and plant protecting systems have an influence on growth, health and yield of plants. Four differently managed organic variants, fertilized since 1998 with green compost, compost from horse manure, horn chips and an unfertilized control were compared with two conventionally managed variants, one with and one without use of herbicide, which were both treated with fungicides and mineral fertilizer. The differences in field characteristics of strawberries in the observed years 2004 and 2005 were low. The use of different organic fertilizers (green compost, horn chips, compost from horse manure) had no influence on soil and fruit diseases in comparison with the unfertilized control. On the basis of the results, organic strawberry production was comparable to conventional production regarding the obtained yield of marketable fruits.
In pome fruit trees, the growth retardant prohexadione-Ca induces the formation of 3-deoxycatechi... more In pome fruit trees, the growth retardant prohexadione-Ca induces the formation of 3-deoxycatechins, which correlates with an increased resistance against fire blight and also against some fungal diseases. The formation of 3-deoxycatechins is due to the channelling of intermediates unusual for pome fruits, which requires the presence of a flavanone 4-reductase (FNR) activity. Here, it is investigated, whether the crop plants strawberry, grapevine, cranberry, cherry, peach, plum, elder, and kiwi fruit react in the same way to prohexadione-Ca application. The presence of FNR activity is shown by enzymatic investigations and the formation of a 3-deoxycatechin after prohexadione-Ca application in planta. Furthermore, by cloning of the corresponding cDNAs and studies with the heterologously expressed enzymes it is shown that the DFR enzymes of grapevine, cranberry and strawberry posses also FNR activity. Conclusively, all the crop plants studied have the potential to form 3-deoxyflavonoids. However, the changes in the flavonoid composition observed after prohexadione-Ca treatment were not exactly the same in all species studied here. In kiwi fruit leaves, a strong accumulation of flavanones rather than the formation of large amounts of 3-deoxycatechins is observed. Wirkung von Prohexadion-Ca auf einige Obstarten: Flavonoidzusammensetzung und Substratspezifität der Dihydroflavonol 4-Reduktasen. Der Wachstumsregulator Prohexadion-Ca kann bei Kernobst die Bildung von 3-Deoxyflavonoiden induzieren, was mit einer erhöhten Resistenz gegen Feuerbrand, aber auch gegen Pilzerkrankungen einhergeht. Das Vorhandensein einer Flavanon 4-Reduktase ist hierbei entscheidend für die Umlenkung von Intermediaten in Richtung der 3-Deoxycatechine. In der vorliegenden Studie wurde untersucht, ob weitere Obstarten wie Erdbeere, Weinrebe, Cranberry, Kirsche, Pfirsich, Pflaume, Holunder und Kiwi gleichermaßen auf eine Prohexadion-Ca Anwendung reagieren. FNR-Aktivität wurde enzymatisch und durch die Bildung eines 3-Deoxycatechins nach Behandlung mit Prohexadion-Ca nachgewiesen. Darüber hinaus wurde durch cDNA-Klonierung und heterologe Expression gezeigt, dass die DFR-Enzyme von Wein, Cranberry und Erdbeere auch FNR-Aktivität besitzen. Generell wurde nachgewiesen, dass alle untersuchten Pflanzen das Potential haben, 3-Deoxyflavonoide zu bilden. Die Veränderungen im Flavonoidstoffwechsel nach Prohexadion-Ca Behandlung waren allerdings in den untersuchten Pflanzen unterschiedlich und führten beispielsweise in Kiwi zu einer starken Akkumulation von Flavanonen. Key words. Actinidia sp. (kiwi fruit) -3-deoxyflavonoids -flavanone 4-reductase (FNR) -Fragaria x ananassa (strawberry) -induced resistance -Prunus domestica (plum) -Vitis vinifera (grapevine) -Prunus persica (peach)
Bidens ferulifolia is a yellow flowering plant, originating from Mexico, which is increasingly po... more Bidens ferulifolia is a yellow flowering plant, originating from Mexico, which is increasingly popular as an ornamental plant. In the past few years, new colour combinations ranging from pure yellow over yellow-red, white-red, pure white and purple have emerged on the market. We analysed 16 Bidens ferulifolia genotypes to provide insight into the (bio)chemical base underlying the colour formation, which involves flavonoids, anthochlors and carotenoids. In all but purple and white genotypes, anthochlors were the prevalent pigments, primarily derivatives of okanin, a 6′-deoxychalcone carrying an unusual 2′3′4′-hydroxylation pattern in ring A. The presence of a cytochrome-P450-dependent monooxygenase introducing the additional hydroxyl group in position 3′ of both isoliquiritigenin and butein was demonstrated for the first time. All genotypes accumulate considerable amounts of the flavone luteolin. Red and purple genotypes additionally accumulate cyanidin-type anthocyanins. Acyanic gen...
Beetroot was grown in an open soilless cultivation system with nutrition supplied by organic and ... more Beetroot was grown in an open soilless cultivation system with nutrition supplied by organic and inorganic sources. This low emission system was tested for microgardening high quality red beets with high water use efficiency and less pollutant emission in the environs. For this purpose, a pot experiment was planned according to completely randomized design. For inorganically grown red beets, peat moss was combined with 150, 200 and 250 ppm NH4NO3, whereas for organic red beets, peat moss was amended with compost having nitrogen equivalent to the mentioned NH4NO3 concentrations. Rosette and roots were analysed for fresh and dry biomass. Nitrate content, total soluble solids, titratable acidity, ripening index, ascorbic acid, betacyanins, flavonols and antioxidant capacity were assessed as beetroot quality attributes. Combination of peat moss with NH4NO3 showed comparatively lower fresh plant biomass, fresh and dry biomasses of rosette and root, and root to rosette ratio. However, enh...
Malus × domestica (apple) accumulates particularly high amounts of dihydrochalcones in various ti... more Malus × domestica (apple) accumulates particularly high amounts of dihydrochalcones in various tissues, with phloridzin (phloretin 2′-O-glucoside) being prevalent, although small amounts of 3-hydroxyphloretin and 3-hydroxyphloridzin are also constitutively present. The latter was shown to correlate with increased disease resistance of transgenic M. × domestica plants. Two types of enzymes could be involved in 3-hydroxylation of dihydrochalcones: polyphenol oxidases or the flavonoid 3′-hydroxylase (F3′H), which catalyzes B-ring hydroxylation of flavonoids. We isolated two F3′H cDNA clones from apple leaves and tested recombinant Malus F3′Hs for their substrate specificity. From the two isolated cDNA clones, only F3′HII encoded a functionally active enzyme. In the F3′HI sequence, we identified two putatively relevant amino acids that were exchanged in comparison to that of a previously published F3′HI. Site directed mutagenesis, which exchanged an isoleucine into methionine in positio...
Background: Commercially available poinsettia (Euphorbia pulcherrima) varieties prevalently accum... more Background: Commercially available poinsettia (Euphorbia pulcherrima) varieties prevalently accumulate cyanidin derivatives and show intense red coloration. Orange-red bract color is less common. We investigated four cultivars displaying four different red hues with respect to selected enzymes and genes of the anthocyanin pathway, putatively determining the color hue. Results: Red hues correlated with anthocyanin composition and concentration and showed common dark red coloration in cultivars 'Christmas Beauty' and 'Christmas Feeling' where cyanidin derivatives were prevalent. In contrast, orange-red bract color is based on the prevalent presence of pelargonidin derivatives that comprised 85% of the total anthocyanin content in cv. 'Premium Red' and 96% in cv. 'Harvest Orange' (synonym: 'Orange Spice'). cDNA clones of flavonoid 3′-hydroxylase (F3′H) and dihydroflavonol 4-reductase (DFR) were isolated from the four varieties, and functional activity and substrate specificity of the corresponding recombinant enzymes were studied. Kinetic studies demonstrated that poinsettia DFRs prefer dihydromyricetin and dihydroquercetin over dihydrokaempferol, and thus, favor the formation of cyanidin over pelargonidin. Whereas the F3′H cDNA clones of cultivars 'Christmas Beauty', 'Christmas Feeling', and 'Premium Red' encoded functionally active enzymes, the F3′H cDNA clone of cv. 'Harvest Orange' contained an insertion of 28 bases, which is partly a duplication of 20 bases found close to the insertion site. This causes a frameshift mutation with a premature stop codon after nucleotide 132 and, therefore, a non-functional enzyme. Heterozygosity of the F3′H was demonstrated in this cultivar, but only the mutated allele was expressed in the bracts. No correlation between F3′H-expression and the color hue could be observed in the four species. Conclusions: Rare orange-red poinsettia hues caused by pelargonidin based anthocyanins can be achieved by different mechanisms. F3′H is a critical step in the establishment of orange red poinsettia color. Although poinsettia DFR shows a low substrate specificity for dihydrokaempferol, sufficient precursor for pelargonidin formation is available in planta, in the absence of F3'H activity.
Hawthorn ( Crataegus sp.) is a traditional medicinal plant, which shows a broad spectrum of healt... more Hawthorn ( Crataegus sp.) is a traditional medicinal plant, which shows a broad spectrum of health-related effects. Drug preparation is based on material collected from wild growing plants, which usually show variability in their secondary metabolite composition and concentration. Plantations of selected hawthorn genotypes could form the basis of a consistent homogeneous source of top-quality hawthorn drugs. However, as hawthorn is a member of the Rosaceae family, such plantations would be threatened by the bacterial disease fire blight, which currently causes dramatic economic losses in apple and pear orchards. We show that prohexadione-Ca induces the formation in Crataegus monogyna leaves of the rare class of 3-deoxyflavonoids, which are responsible for better fire blight resistance and that the quality and quantity of the health related ingredients are not negatively influenced by prohexadione-Ca treatment.
Dahlia ( Dahlia variabilis) exists in a dazzling array of cultivars, showing red, orange, magenta... more Dahlia ( Dahlia variabilis) exists in a dazzling array of cultivars, showing red, orange, magenta, lilac, yellow and white flower color, which is exclusively based on the presence of flavonoids and biochemically related compounds. Red hues (red, orange, magenta, lilac) are a result of anthocyanin accumulation in varying concentration and composition, while a yellow color is based on the formation of 6′-deoxychalcones in the petals. Red dahlia pigments are all derived from pelargonidin and cyanidin. Delphinidin derivatives are not formed due to the absence of flavonoid 3′,5′-hydroxylase in dahlia petals, which provides an explanation for the lack of blue dahlia flowers. Orange, lilac and rose cultivars are characterized by a lower anthocyanin content compared to many red cultivars. We investigated 198 cultivars for the presence of flavonoid enzymes. The activities of chalcone isomerase (CHI), chalcone synthase (CHS), dihydroflavonol 4-reductase (DFR), flavanone 3-hydroxylase (FHT), f...
The influence of two foliar applications of Phostrade Ca, which contains high concentrations of p... more The influence of two foliar applications of Phostrade Ca, which contains high concentrations of phosphorus and minor amounts of calcium and nitrogen, on color development and selected primary and secondary metabolites was investigated during advanced maturation of ‘Braeburn’ apple. Changes of hydroxycinnamic acids, flavanols, dihydrochalcones, flavonols, and anthocyanins were monitored six times during the advanced ripening until technological maturity of the fruits. Additionally, the changes in the chromatic values a*, h°, and the lightness coefficient L* were recorded weekly. The colorimetric parameters showed a significant difference in the intensity of red coloration between the treated and untreated apples. Spraying with Phostrade Ca also resulted in a significant increase in most individual sugars, total sugars, and concentration of anthocyanins and flavonols. Moreover, the amount of phosphorus (P) in the treated leaves was increased. However, the total phenolic content and ac...
Flavonol synthase (FLS) was demonstrated in crude extracts from flower buds of Dianthus caryophyl... more Flavonol synthase (FLS) was demonstrated in crude extracts from flower buds of Dianthus caryophyllus (carnation). The enzyme catalyzed the conversion of dihydrokaempferol and ihydroquercetin to kaempferol and quercetin, respectively. The reaction required 2-oxoglutarate, ferrous ion and ascorbate as co-factors and had a pH optimum at about 7.4. The demonstration of FLS activity allowed comparative studies on flavonol and anthocyanin biosynthesis during bud and flower development. Besides FLS the flavonoid enzymes chalcone synthase (CHS), flavanone 3-hydroxylase (FH T) and dihydroflavonol 4-reductase (DFR) were measured. DFR is specifically involved in anthocyanin synthesis, while CHS and FHT provide dihydroflavonol, the common substrate for both FLS and DFR . Maximum expression of CHS, FHT and FLS activity was already observed in small buds, whereas DFR activity started to increase much later and reached its highest level in opened flowers. A substantial correlation was observed bet...
A recall campaign for commercial, orange flowering petunia varieties in spring 2017 caused econom... more A recall campaign for commercial, orange flowering petunia varieties in spring 2017 caused economic losses worldwide. The orange varieties were identified as undeclared genetically engineered (GE)-plants, harboring a maize dihydroflavonol 4-reductase (), which was used in former scientific transgenic breeding attempts to enable formation of orange pelargonidin derivatives from the precursor dihydrokaempferol (DHK) in petunia. How and when the cDNA entered the commercial breeding process is unclear. We provide an in-depth analysis of three orange petunia varieties, released by breeders from three countries, with respect to their transgenic construct, transcriptomes, anthocyanin composition, and flavonoid metabolism at the level of selected enzymes and genes. The two possible sources of the cDNA in the undeclared GE-petunia can be discriminated by PCR. A special version of the gene, the type 2 allele, is present, which includes, at the 3'-end, an additional 144 bp segment from the...
The Journal of Horticultural Science and Biotechnology, 2010
This study investigated the activities of key enzymes in the phenylpropanoid pathway and the accu... more This study investigated the activities of key enzymes in the phenylpropanoid pathway and the accumulation of phenolic products in apple peel in response to infection with Venturia inaequalis [(Cooke) G. Wint.]. We compared healthy apple peel with apple peel showing symptomatic scab lesions, and with peel tissue from 1 -2 mm around the scab lesions in fruit 1 month before maturity [140 d after full bloom (DAFB)] and at physiological maturity (175 DAFB). Infection with V. inaequalis enhanced the synthesis of some phenolic compounds. Compared to healthy peel, scab lesion tissue had ≤ 3.1-times higher hydroxycinnamic acid content, ≤ 1.3-times higher dihydrochalcone content, and ≤ 3.9-times higher flavan-3-ol content. Scab lesions showed slightly higher phenylalanine ammonia-lyase, chalcone synthase, chalcone isomerase, flavonol synthase, and dihydroflavonol 4-reductase activities. The total amount of phenolics remained relatively stable between the two sampling dates, except for epicatechin and caffeic acid which decreased in amount toward fruit maturity, and levels of catechin which increased in more mature fruit. During fruit maturation, only chalcone synthase and chalcone isomerase activities decreased in all tissues examined. This study showed that the phenylpropanoid pathway in apple fruit peel changed significantly following infection with the apple scab pathogen.
European Journal of Horticultural Science, Apr 20, 2009
As part of a research project 13 cultivars were planted in 2005 at 11 sites in 5 different Austri... more As part of a research project 13 cultivars were planted in 2005 at 11 sites in 5 different Austrian regions. The aim was to find new cultivars tolerant to the soil-borne pathogen Verticillium dahliae and to leaf/fruit diseases, with high yield and good fruit quality, to serve as alternative to 'Elsanta', a highly susceptible cultivar regarding soil-borne diseases. Infestation with V. dahliae was evaluated in 2005 and 2006 at 7 sites and in 2007 at 3 sites. Moreover marketable yield, percentage of different categories of unmarketable fruits, plant vigour, and incidence of the blossom weevil Anthonomus rubi, of chlorosis and of leaf spot diseases were assessed on 2 of the sites in 2006 and 2007. 'Elsanta' showed the highest infestation with V. dahliae whereas 'Salsa' and 'Daroyal' were most tolerant. 'Daroyal', 'Queen Elisa', 'Eva' and 'Dora' showed very high plant vigour. 'Dora', 'Eva', 'Queen Elisa' and 'Daroyal' recorded significantly higher losses by the blossom weevil than 'Alice'. Highest marketable yield per plant had the late ripening cultivars, particularly 'Salsa' and 'Sonata'. Of all early ripening cultivars tested, 'Darselect' showed the highest yield, followed by 'Elsanta', 'Daroyal' and 'Alba'. Summing up all the results, 'Alba', 'Alice', 'Daroyal', 'Darselect' and 'Salsa' can be recommended for organic production. 'Elsanta' and 'Sonata' had high yield under organic farming conditions, but are highly susceptible to V. dahliae. 'Salsa', 'Daroyal', 'Alice', 'Record' and 'Queen Elisa' are suitable for growing in Verticillium-infested soils. As new alternatives to 'Elsanta', the early ripening cultivars 'Alba', 'Clery', 'Daroyal' and 'Queen Elisa' can be used, though 'Clery' and 'Queen Elisa' had rather low yield under organic farming conditions and 'Alba' and 'Clery' are only partially tolerant to V. dahliae. 'Divine' and 'Dora' had low yield and are susceptible to Verticillium-wilt and 'Record' is prone to grey mould. These cultivars cannot be recommended for organic production.
Soil-borne pathogens, above all Verticillium sp. cause plant losses and yield decreases in many A... more Soil-borne pathogens, above all Verticillium sp. cause plant losses and yield decreases in many Austrian strawberry fields, also in organic farming systems; in a research project possibilities to resolve this problem were examined. In a field trial, which was started 1998, organically managed and differently fertilized plots (green compost, manure, hornchips) were compared to an unfertilised control plot and to two mineral fertilized and conventionally treated plots; the differences in field characteristics of strawberries in 2004 and 2005 were low, but differences in storage and biochemical characteristics could be seen in 2005. Some new cultivars tested as alternative to the very sensitive 'Elsanta' planted in 2005 on several farms showed a higher tolerance to diseases and good yield and fruit quality characteristics. Brassica sp. planted as an intercrop before strawberries reduced the amount of microsclerotia of Verticillium dahliae in highly infested soils, nevertheless the system has to be optimised and adapted to our climatic and husbandry conditions in further trials.
As part of a research project 13 cultivars were planted in 2005 at 11 sites on 9 farms in 5 diffe... more As part of a research project 13 cultivars were planted in 2005 at 11 sites on 9 farms in 5 different Austrian regions. The aim was to find new cultivars tolerant to soil-borne pathogens and leaf/fruit diseases, with high yield, winter hardness and good fruit quality, to serve as alternative to the highly susceptible cultivar 'Elsanta', regarding soil-borne diseases. Plant vigour and infestation with Verticillium dahliae and leaf diseases were evaluated in 2005 und 2006 at 7 sites and in 2007 at 3 sites. In addition, following parameters were assessed on 2 organically managed sites in 2006 and 2007: marketable yield, percentage of different categories of unmarketable fruits and incidence of the blossom weevil. In 2006 fruit characteristics and consumer acceptance were studied. 'Elsanta' showed the highest infestation with V. dahliae whereas 'Salsa', 'Daroyal' and 'Alice' were most tolerant. 'Dora', 'Eva', 'Queen Elisa' and 'Daroyal' recorded significantly higher losses by the blossom weevil than 'Alice'. 'Alba' and 'Divine' were the earliest cultivars in ripening time. Highest marketable yield per plant had the late ripening cultivars, particularly 'Salsa' and 'Sonata'.
Soil-borne pathogens, above all Verticillium sp. cause plant losses and yield decreases in many A... more Soil-borne pathogens, above all Verticillium sp. cause plant losses and yield decreases in many Austrian strawberry fields, also in organic farming systems; in a research project possibilities to resolve this problem were examined. In a field trial, which was started 1998, organically managed and differently fertilized plots (green compost, manure, hornchips) were compared to an unfertilised control plot and to two mineral fertilized and conventionally treated plots; the differences in field characteristics of strawberries in 2004 and 2005 were low, but differences in storage and biochemical characteristics could be seen in 2005. Some new cultivars tested as alternative to the very sensitive 'Elsanta' planted in 2005 on several farms showed a higher tolerance to diseases and good yield and fruit quality characteristics. Brassica sp. planted as an intercrop before strawberries reduced the amount of microsclerotia of Verticillium dahliae in highly infested soils, nevertheless the system has to be optimised and adapted to our climatic and husbandry conditions in further trials.
Malus × domestica (apple) accumulates particularly high amounts of dihydrochalcones in various ti... more Malus × domestica (apple) accumulates particularly high amounts of dihydrochalcones in various tissues, with phloridzin (phloretin 2 -O-glucoside) being prevalent, although small amounts of 3-hydroxyphloretin and 3-hydroxyphloridzin are also constitutively present. The latter was shown to correlate with increased disease resistance of transgenic M. × domestica plants. Two types of enzymes could be involved in 3-hydroxylation of dihydrochalcones: polyphenol oxidases or the flavonoid 3 -hydroxylase (F3 H), which catalyzes B-ring hydroxylation of flavonoids. We isolated two F3 H cDNA clones from apple leaves and tested recombinant Malus F3 Hs for their substrate specificity. From the two isolated cDNA clones, only F3 HII encoded a functionally active enzyme. In the F3 HI sequence, we identified two putatively relevant amino acids that were exchanged in comparison to that of a previously published F3 HI. Site directed mutagenesis, which exchanged an isoleucine into methionine in position 211 restored the functional activity, which is probably because it is located in an area involved in interaction with the substrate. In contrast to high activity with various flavonoid substrates, the recombinant enzymes did not accept phloretin under assay conditions, making an involvement in the dihydrochalcone biosynthesis unlikely.
Bidens ferulifolia is a yellow flowering plant, originating from Mexico, which is increasingly po... more Bidens ferulifolia is a yellow flowering plant, originating from Mexico, which is increasingly popular as an ornamental plant. In the past few years, new colour combinations ranging from pure yellow over yellow-red, white-red, pure white and purple have emerged on the market. We analysed 16 Bidens ferulifolia genotypes to provide insight into the (bio)chemical base underlying the colour formation, which involves flavonoids, anthochlors and carotenoids. In all but purple and white genotypes, anthochlors were the prevalent pigments, primarily derivatives of okanin, a 6 -deoxychalcone carrying an unusual 2 3 4 -hydroxylation pattern in ring A. The presence of a cytochrome-P450-dependent monooxygenase introducing the additional hydroxyl group in position 3 of both isoliquiritigenin and butein was demonstrated for the first time. All genotypes accumulate considerable amounts of the flavone luteolin. Red and purple genotypes additionally accumulate cyanidin-type anthocyanins. Acyanic genotypes lack flavanone 3-hydroxylase and/or dihydroflavonol 4-reductase activity, which creates a bottleneck in the anthocyanin pathway. The carotenoid spectrum was analysed in two Bidens genotypes and showed strong variation between the two cultivars. In comparison to anthochlors, carotenoids were present in much lower concentrations. Carotenoid monoesters, as well as diesters, were determined for the first time in B. ferulifolia flower extracts.
ABSTRACT In 2004 and 2005, strawberries (cultivar Elsanta) were tested under different management... more ABSTRACT In 2004 and 2005, strawberries (cultivar Elsanta) were tested under different management systems in a field trial to find out if different fertilizing and plant protecting systems have an influence on growth, health and yield of plants. Four differently managed organic variants, fertilized since 1998 with green compost, compost from horse manure, horn chips and an unfertilized control were compared with two conventionally managed variants, one with and one without use of herbicide, which were both treated with fungicides and mineral fertilizer. The differences in field characteristics of strawberries in the observed years 2004 and 2005 were low. The use of different organic fertilizers (green compost, horn chips, compost from horse manure) had no influence on soil and fruit diseases in comparison with the unfertilized control. On the basis of the results, organic strawberry production was comparable to conventional production regarding the obtained yield of marketable fruits.
In pome fruit trees, the growth retardant prohexadione-Ca induces the formation of 3-deoxycatechi... more In pome fruit trees, the growth retardant prohexadione-Ca induces the formation of 3-deoxycatechins, which correlates with an increased resistance against fire blight and also against some fungal diseases. The formation of 3-deoxycatechins is due to the channelling of intermediates unusual for pome fruits, which requires the presence of a flavanone 4-reductase (FNR) activity. Here, it is investigated, whether the crop plants strawberry, grapevine, cranberry, cherry, peach, plum, elder, and kiwi fruit react in the same way to prohexadione-Ca application. The presence of FNR activity is shown by enzymatic investigations and the formation of a 3-deoxycatechin after prohexadione-Ca application in planta. Furthermore, by cloning of the corresponding cDNAs and studies with the heterologously expressed enzymes it is shown that the DFR enzymes of grapevine, cranberry and strawberry posses also FNR activity. Conclusively, all the crop plants studied have the potential to form 3-deoxyflavonoids. However, the changes in the flavonoid composition observed after prohexadione-Ca treatment were not exactly the same in all species studied here. In kiwi fruit leaves, a strong accumulation of flavanones rather than the formation of large amounts of 3-deoxycatechins is observed. Wirkung von Prohexadion-Ca auf einige Obstarten: Flavonoidzusammensetzung und Substratspezifität der Dihydroflavonol 4-Reduktasen. Der Wachstumsregulator Prohexadion-Ca kann bei Kernobst die Bildung von 3-Deoxyflavonoiden induzieren, was mit einer erhöhten Resistenz gegen Feuerbrand, aber auch gegen Pilzerkrankungen einhergeht. Das Vorhandensein einer Flavanon 4-Reduktase ist hierbei entscheidend für die Umlenkung von Intermediaten in Richtung der 3-Deoxycatechine. In der vorliegenden Studie wurde untersucht, ob weitere Obstarten wie Erdbeere, Weinrebe, Cranberry, Kirsche, Pfirsich, Pflaume, Holunder und Kiwi gleichermaßen auf eine Prohexadion-Ca Anwendung reagieren. FNR-Aktivität wurde enzymatisch und durch die Bildung eines 3-Deoxycatechins nach Behandlung mit Prohexadion-Ca nachgewiesen. Darüber hinaus wurde durch cDNA-Klonierung und heterologe Expression gezeigt, dass die DFR-Enzyme von Wein, Cranberry und Erdbeere auch FNR-Aktivität besitzen. Generell wurde nachgewiesen, dass alle untersuchten Pflanzen das Potential haben, 3-Deoxyflavonoide zu bilden. Die Veränderungen im Flavonoidstoffwechsel nach Prohexadion-Ca Behandlung waren allerdings in den untersuchten Pflanzen unterschiedlich und führten beispielsweise in Kiwi zu einer starken Akkumulation von Flavanonen. Key words. Actinidia sp. (kiwi fruit) -3-deoxyflavonoids -flavanone 4-reductase (FNR) -Fragaria x ananassa (strawberry) -induced resistance -Prunus domestica (plum) -Vitis vinifera (grapevine) -Prunus persica (peach)
Bidens ferulifolia is a yellow flowering plant, originating from Mexico, which is increasingly po... more Bidens ferulifolia is a yellow flowering plant, originating from Mexico, which is increasingly popular as an ornamental plant. In the past few years, new colour combinations ranging from pure yellow over yellow-red, white-red, pure white and purple have emerged on the market. We analysed 16 Bidens ferulifolia genotypes to provide insight into the (bio)chemical base underlying the colour formation, which involves flavonoids, anthochlors and carotenoids. In all but purple and white genotypes, anthochlors were the prevalent pigments, primarily derivatives of okanin, a 6′-deoxychalcone carrying an unusual 2′3′4′-hydroxylation pattern in ring A. The presence of a cytochrome-P450-dependent monooxygenase introducing the additional hydroxyl group in position 3′ of both isoliquiritigenin and butein was demonstrated for the first time. All genotypes accumulate considerable amounts of the flavone luteolin. Red and purple genotypes additionally accumulate cyanidin-type anthocyanins. Acyanic gen...
Beetroot was grown in an open soilless cultivation system with nutrition supplied by organic and ... more Beetroot was grown in an open soilless cultivation system with nutrition supplied by organic and inorganic sources. This low emission system was tested for microgardening high quality red beets with high water use efficiency and less pollutant emission in the environs. For this purpose, a pot experiment was planned according to completely randomized design. For inorganically grown red beets, peat moss was combined with 150, 200 and 250 ppm NH4NO3, whereas for organic red beets, peat moss was amended with compost having nitrogen equivalent to the mentioned NH4NO3 concentrations. Rosette and roots were analysed for fresh and dry biomass. Nitrate content, total soluble solids, titratable acidity, ripening index, ascorbic acid, betacyanins, flavonols and antioxidant capacity were assessed as beetroot quality attributes. Combination of peat moss with NH4NO3 showed comparatively lower fresh plant biomass, fresh and dry biomasses of rosette and root, and root to rosette ratio. However, enh...
Malus × domestica (apple) accumulates particularly high amounts of dihydrochalcones in various ti... more Malus × domestica (apple) accumulates particularly high amounts of dihydrochalcones in various tissues, with phloridzin (phloretin 2′-O-glucoside) being prevalent, although small amounts of 3-hydroxyphloretin and 3-hydroxyphloridzin are also constitutively present. The latter was shown to correlate with increased disease resistance of transgenic M. × domestica plants. Two types of enzymes could be involved in 3-hydroxylation of dihydrochalcones: polyphenol oxidases or the flavonoid 3′-hydroxylase (F3′H), which catalyzes B-ring hydroxylation of flavonoids. We isolated two F3′H cDNA clones from apple leaves and tested recombinant Malus F3′Hs for their substrate specificity. From the two isolated cDNA clones, only F3′HII encoded a functionally active enzyme. In the F3′HI sequence, we identified two putatively relevant amino acids that were exchanged in comparison to that of a previously published F3′HI. Site directed mutagenesis, which exchanged an isoleucine into methionine in positio...
Background: Commercially available poinsettia (Euphorbia pulcherrima) varieties prevalently accum... more Background: Commercially available poinsettia (Euphorbia pulcherrima) varieties prevalently accumulate cyanidin derivatives and show intense red coloration. Orange-red bract color is less common. We investigated four cultivars displaying four different red hues with respect to selected enzymes and genes of the anthocyanin pathway, putatively determining the color hue. Results: Red hues correlated with anthocyanin composition and concentration and showed common dark red coloration in cultivars 'Christmas Beauty' and 'Christmas Feeling' where cyanidin derivatives were prevalent. In contrast, orange-red bract color is based on the prevalent presence of pelargonidin derivatives that comprised 85% of the total anthocyanin content in cv. 'Premium Red' and 96% in cv. 'Harvest Orange' (synonym: 'Orange Spice'). cDNA clones of flavonoid 3′-hydroxylase (F3′H) and dihydroflavonol 4-reductase (DFR) were isolated from the four varieties, and functional activity and substrate specificity of the corresponding recombinant enzymes were studied. Kinetic studies demonstrated that poinsettia DFRs prefer dihydromyricetin and dihydroquercetin over dihydrokaempferol, and thus, favor the formation of cyanidin over pelargonidin. Whereas the F3′H cDNA clones of cultivars 'Christmas Beauty', 'Christmas Feeling', and 'Premium Red' encoded functionally active enzymes, the F3′H cDNA clone of cv. 'Harvest Orange' contained an insertion of 28 bases, which is partly a duplication of 20 bases found close to the insertion site. This causes a frameshift mutation with a premature stop codon after nucleotide 132 and, therefore, a non-functional enzyme. Heterozygosity of the F3′H was demonstrated in this cultivar, but only the mutated allele was expressed in the bracts. No correlation between F3′H-expression and the color hue could be observed in the four species. Conclusions: Rare orange-red poinsettia hues caused by pelargonidin based anthocyanins can be achieved by different mechanisms. F3′H is a critical step in the establishment of orange red poinsettia color. Although poinsettia DFR shows a low substrate specificity for dihydrokaempferol, sufficient precursor for pelargonidin formation is available in planta, in the absence of F3'H activity.
Hawthorn ( Crataegus sp.) is a traditional medicinal plant, which shows a broad spectrum of healt... more Hawthorn ( Crataegus sp.) is a traditional medicinal plant, which shows a broad spectrum of health-related effects. Drug preparation is based on material collected from wild growing plants, which usually show variability in their secondary metabolite composition and concentration. Plantations of selected hawthorn genotypes could form the basis of a consistent homogeneous source of top-quality hawthorn drugs. However, as hawthorn is a member of the Rosaceae family, such plantations would be threatened by the bacterial disease fire blight, which currently causes dramatic economic losses in apple and pear orchards. We show that prohexadione-Ca induces the formation in Crataegus monogyna leaves of the rare class of 3-deoxyflavonoids, which are responsible for better fire blight resistance and that the quality and quantity of the health related ingredients are not negatively influenced by prohexadione-Ca treatment.
Dahlia ( Dahlia variabilis) exists in a dazzling array of cultivars, showing red, orange, magenta... more Dahlia ( Dahlia variabilis) exists in a dazzling array of cultivars, showing red, orange, magenta, lilac, yellow and white flower color, which is exclusively based on the presence of flavonoids and biochemically related compounds. Red hues (red, orange, magenta, lilac) are a result of anthocyanin accumulation in varying concentration and composition, while a yellow color is based on the formation of 6′-deoxychalcones in the petals. Red dahlia pigments are all derived from pelargonidin and cyanidin. Delphinidin derivatives are not formed due to the absence of flavonoid 3′,5′-hydroxylase in dahlia petals, which provides an explanation for the lack of blue dahlia flowers. Orange, lilac and rose cultivars are characterized by a lower anthocyanin content compared to many red cultivars. We investigated 198 cultivars for the presence of flavonoid enzymes. The activities of chalcone isomerase (CHI), chalcone synthase (CHS), dihydroflavonol 4-reductase (DFR), flavanone 3-hydroxylase (FHT), f...
The influence of two foliar applications of Phostrade Ca, which contains high concentrations of p... more The influence of two foliar applications of Phostrade Ca, which contains high concentrations of phosphorus and minor amounts of calcium and nitrogen, on color development and selected primary and secondary metabolites was investigated during advanced maturation of ‘Braeburn’ apple. Changes of hydroxycinnamic acids, flavanols, dihydrochalcones, flavonols, and anthocyanins were monitored six times during the advanced ripening until technological maturity of the fruits. Additionally, the changes in the chromatic values a*, h°, and the lightness coefficient L* were recorded weekly. The colorimetric parameters showed a significant difference in the intensity of red coloration between the treated and untreated apples. Spraying with Phostrade Ca also resulted in a significant increase in most individual sugars, total sugars, and concentration of anthocyanins and flavonols. Moreover, the amount of phosphorus (P) in the treated leaves was increased. However, the total phenolic content and ac...
Flavonol synthase (FLS) was demonstrated in crude extracts from flower buds of Dianthus caryophyl... more Flavonol synthase (FLS) was demonstrated in crude extracts from flower buds of Dianthus caryophyllus (carnation). The enzyme catalyzed the conversion of dihydrokaempferol and ihydroquercetin to kaempferol and quercetin, respectively. The reaction required 2-oxoglutarate, ferrous ion and ascorbate as co-factors and had a pH optimum at about 7.4. The demonstration of FLS activity allowed comparative studies on flavonol and anthocyanin biosynthesis during bud and flower development. Besides FLS the flavonoid enzymes chalcone synthase (CHS), flavanone 3-hydroxylase (FH T) and dihydroflavonol 4-reductase (DFR) were measured. DFR is specifically involved in anthocyanin synthesis, while CHS and FHT provide dihydroflavonol, the common substrate for both FLS and DFR . Maximum expression of CHS, FHT and FLS activity was already observed in small buds, whereas DFR activity started to increase much later and reached its highest level in opened flowers. A substantial correlation was observed bet...
A recall campaign for commercial, orange flowering petunia varieties in spring 2017 caused econom... more A recall campaign for commercial, orange flowering petunia varieties in spring 2017 caused economic losses worldwide. The orange varieties were identified as undeclared genetically engineered (GE)-plants, harboring a maize dihydroflavonol 4-reductase (), which was used in former scientific transgenic breeding attempts to enable formation of orange pelargonidin derivatives from the precursor dihydrokaempferol (DHK) in petunia. How and when the cDNA entered the commercial breeding process is unclear. We provide an in-depth analysis of three orange petunia varieties, released by breeders from three countries, with respect to their transgenic construct, transcriptomes, anthocyanin composition, and flavonoid metabolism at the level of selected enzymes and genes. The two possible sources of the cDNA in the undeclared GE-petunia can be discriminated by PCR. A special version of the gene, the type 2 allele, is present, which includes, at the 3'-end, an additional 144 bp segment from the...
The Journal of Horticultural Science and Biotechnology, 2010
This study investigated the activities of key enzymes in the phenylpropanoid pathway and the accu... more This study investigated the activities of key enzymes in the phenylpropanoid pathway and the accumulation of phenolic products in apple peel in response to infection with Venturia inaequalis [(Cooke) G. Wint.]. We compared healthy apple peel with apple peel showing symptomatic scab lesions, and with peel tissue from 1 -2 mm around the scab lesions in fruit 1 month before maturity [140 d after full bloom (DAFB)] and at physiological maturity (175 DAFB). Infection with V. inaequalis enhanced the synthesis of some phenolic compounds. Compared to healthy peel, scab lesion tissue had ≤ 3.1-times higher hydroxycinnamic acid content, ≤ 1.3-times higher dihydrochalcone content, and ≤ 3.9-times higher flavan-3-ol content. Scab lesions showed slightly higher phenylalanine ammonia-lyase, chalcone synthase, chalcone isomerase, flavonol synthase, and dihydroflavonol 4-reductase activities. The total amount of phenolics remained relatively stable between the two sampling dates, except for epicatechin and caffeic acid which decreased in amount toward fruit maturity, and levels of catechin which increased in more mature fruit. During fruit maturation, only chalcone synthase and chalcone isomerase activities decreased in all tissues examined. This study showed that the phenylpropanoid pathway in apple fruit peel changed significantly following infection with the apple scab pathogen.
Uploads
Papers by Karl Stich