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Ludger Beerhues - One of the best experts on this subject based on the ideXlab platform.
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immunolocalization of biphenyl synthase in elicitor treated cell cultures of Sorbus aucuparia
Acta Horticulturae, 2014Co-Authors: Dennis Reckwell, Robert Hansch, Jutta Schulze, Ludger BeerhuesAbstract:In response to infection, Malinae produce biphenyls and dibenzofurans as phytoalexins. In spite of the economic importance of the Malinae biosynthesis of their phytoalexins is poorly understood. The key enzyme which forms the carbon skeleton is biphenyl synthase (BIS). This protein was immunochemically detected in Sorbus aucuparia cell cultures treated with an autoclaved suspension of Erwinia amylovora. Immunofluorescence appeared as discrete globules and localized at the surface of the cells, suggesting association of BIS with plasmodesmata.
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biosynthesis of the biphenyl phytoalexin aucuparin in Sorbus aucuparia cell cultures treated with venturia inaequalis
Phytochemistry, 2013Co-Authors: Mohammed N A Khalil, Till Beuerle, Ludger Ernst, Andreas Muller, Vijaya B R Bhavanam, Ludger BeerhuesAbstract:Abstract Aucuparin is the most widely distributed biphenyl phytoalexin in the rosaceous subtribe Pyrinae, which includes the economically important fruit trees apple and pear. The biphenyl scaffold is formed by biphenyl synthase, which catalyzes biosynthesis of 3,5-dihydroxybiphenyl. Conversion of this precursor to aucuparin (3,5-dimethoxy-4-hydroxybiphenyl) was studied in cell cultures of Sorbus aucuparia after treatment with an elicitor preparation from the scab-causing fungus Venturia inaequalis . The sequence of the biosynthetic steps detected was O -methylation – 4-hydroxylation – O -methylation. The two alkylation reactions were catalyzed by distinct methyltransferases, which differed in pH and temperature optima as well as stability. Biphenyl 4-hydroxylase was a microsomal cytochrome P450 monooxygenase, whose activity was appreciably decreased by the addition of established P450 inhibitors. When fed to V. inaequalis -treated S. aucuparia cell cultures, radioactively labeled 3,5-dihydroxybiphenyl was not only incorporated into aucuparin but also into the dibenzofuran eriobofuran, the accumulation of which paralleled that of aucuparin. However, biphenyl 2′-hydroxylase activity proposed to be involved in dibenzofuran formation was detected in neither microsomes nor cell-free extracts in the presence of NADPH and 2-oxoglutarate, respectively. Nevertheless, a basis for studying biphenyl biosynthesis at the gene level is provided.
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endogenous hydrogen peroxide is a key factor in the yeast extract induced activation of biphenyl biosynthesis in cell cultures of Sorbus aucuparia
Planta, 2012Co-Authors: Lili Huang, Xing Li, Zhigao Du, Hong Wang, Hechun Ye, Ludger BeerhuesAbstract:Biphenyls are unique phytoalexins produced by plants belonging to Pyrinae, a subtribe of the economically important Rosaceae family. The formation of aucuparin, a well-known biphenyl, is induced by yeast extract (YE) in cell cultures of Sorbus aucuparia. However, the molecular mechanism underlying YE-induced activation of biphenyl biosynthesis remains unknown. Here we demonstrate that the addition of YE to the cell cultures results in a burst of reactive oxygen species (ROS; H2O2 and O2 −), followed by transcriptional activation of the biphenyl synthase 1 gene (BIS1) encoding the key enzyme of the biphenyl biosynthetic pathway and aucuparin accumulation. Pretreatment of the cell cultures with ROS scavenger dihydrolipoic acid and NADPH oxidase-specific inhibitor diphenylene iodonium abolished all of the above YE-induced biological events. However, when the cell cultures was pretreated with superoxide dismutase specific inhibitor N,N-diethyldithiocarbamic acid, although O2 − continued to be generated, the H2O2 accumulation, BIS1 expression and aucuparin production were blocked. Interestingly, exogenous supply of H2O2 in the range of 0.05–10 mM failed to induce aucuparin accumulation. These results indicate that endogenous generation of H2O2 rather than that of O2 − is a key factor in YE-induced accumulation of biphenyl phytoalexins in cell cultures of S. aucuparia.
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4 coumarate coa ligase family members from elicitor treated Sorbus aucuparia cell cultures
Journal of Plant Physiology, 2011Co-Authors: Mariam Gaid, Till Beuerle, Helge Scharnhop, Hussein Ramadan, Ludger BeerhuesAbstract:Abstract Sorbus aucuparia cell cultures accumulate biphenyl and dibenzofuran phytoalexins in response to elicitor treatment. These polyketide derivatives arise from the starter substrate benzoyl-CoA, the biosynthesis of which is largely unresolved. Two CoA ligases involved are cinnamate:CoA ligase and benzoate:CoA ligase, which were assumed to be related in S. aucuparia to the ubiquitous 4-coumarate:CoA ligase (4CL). cDNAs encoding three distinct 4CLs from elicitor-treated S. aucuparia cell cultures were isolated using RT-PCR and RACE techniques and functionally expressed in Escherichia coli as His 6 -tagged proteins (Sa4CL2 and Sa4CL3) or GST-fusion protein (Sa4CL1). All three isoenzymes preferred 4-coumaric acid over cinnamic acid in spectrophotometric assays and failed to utilize benzoic acid in radioisotopic assays. After elicitor treatment of S. aucuparia cell cultures, the transcript levels of all three Sa4CLs increased but were significantly lower than the maximum expression rates of the phenylalanine ammonia-lyase ( PAL ) and biphenyl synthase 1 ( BIS 1) genes. The substrate specificities and the expression profiles indicate that the three 4CL isoenzymes are not involved in benzoyl-CoA biosynthesis in S. aucuparia cell cultures. Sa4CL3 and PAL transcripts also accumulated in response to light treatment. Phylogenetically, Sa4CL1 and Sa4CL2 belong to the class I cluster and Sa4CL3 groups in the class II cluster. Sa4CL3 contains a 49-amino acid N-terminal extension, which includes a chloroplast sorting signal.
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differential effect of elicitors on biphenyl and dibenzofuran formation in Sorbus aucuparia cell cultures
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Cornelia Huttner, Till Beuerle, Helge Scharnhop, Ludger Ernst, Ludger BeerhuesAbstract:The Rosaceous subtribe Pyrinae (formerly subfamily Maloideae) is well-known for its economically important fruit trees, such as apple and pear, and also includes Sorbus aucuparia. Elicitor-treated S. aucuparia cell cultures are used to study the biosynthesis of the Pyrinae-specific phytoalexins, biphenyls and dibenzofurans. Three biphenyls (aucuparin, noraucuparin, 2′-hydroxyaucuparin) and a dibenzofuran (eriobofuran) were isolated and structure elucidated using GC-MS and NMR. A second dibenzofuran of low abundance was tentatively assigned as noreriobofuran. Treatment of S. aucuparia cell cultures with yeast extract induced the formation of aucuparin as the major phytoalexin. In contrast, addition of preparations from the fire blight bacterium, Erwinia amylovora, and the scab-causing fungus, Venturia inaequalis, resulted in accumulation of eriobofuran as the major inducible constituent. Methyl jasmonate was a poor elicitor. The observations are suggestive of a biogenic relationship between biphenyls and d...
Goran Hogstedt - One of the best experts on this subject based on the ideXlab platform.
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corrigendum to avian gut passage reduces seed exit costs in Sorbus aucuparia rosaceae as measured by a diametral compression test
Functional Plant Biology, 2006Co-Authors: Torbjorn Rage Paulsen, Ommund Lindtjorn, Nils Roar Gjerdet, Goran HogstedtAbstract:Reduced seed exit costs have been suggested to explain advanced seedling emergence and increased seedling growth in Sorbus aucuparia L. (Rosaceae; rowan) following Turdus spp. (Turdidae; thrush) gut passage. In the present study, seed coat tension strength of Turdus merula L. (Turdidae; blackbird) gut-passed and non-ingested control seeds were tested with a diametral compression test. Both maximum load (N) and work (mJ) required for opening the seeds were reduced in gut-passed seeds, although scanning electron microscopy showed no visible differences in seed coat surface structure between treatments. In addition, gut passage increased dry seed weight by 0.64 mg (22%), weight of hydrated seeds by 0.62 mg (16%) and width of hydrated seeds by 0.1 mm (9%). Absorption causing the seed coat to yield more easily to the germinating seedling is proposed as an explanation for the reduction in seed exit costs. For the emerging seedling, the time and force needed to open the seed coat was reduced, thus lowering dispersal and germination costs of S. aucuparia.
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avian gut passage reduces seed exit costs in Sorbus aucuparia rosaceae as measured by a diametral compression test
Functional Plant Biology, 2006Co-Authors: Torbjorn Rage Paulsen, Ommund Lindtjorn, Nils Roar Gjerdet, Goran HogstedtAbstract:Reduced seed exit costs have been suggested to explain advanced seedling emergence and increased seedling growth in Sorbus aucuparia L. (Rosaceae; rowan) following Turdus spp. (Turdidae; thrush) gut passage. In the present study, seed coat tension strength of Turdus merula L. (Turdidae; blackbird) gut-passed and non-ingested control seeds were tested with a diametral compression test. Both maximum load (N) and work (mJ) required for opening the seeds were reduced in gut-passed seeds, although scanning electron microscopy showed no visible differences in seed coat surface structure between treatments. In addition, gut passage increased dry seed weight by 0.64 mg (22%), weight of hydrated seeds by 0.62 mg (16%) and width of hydrated seeds by 0.1 mm (9%). Absorption causing the seed coat to yield more easily to the germinating seedling is proposed as an explanation for the reduction in seed exit costs. For the emerging seedling, the time and force needed to open the seed coat was reduced, thus lowering dispersal and germination costs of S. aucuparia.
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passage through bird guts increases germination rate and seedling growth in Sorbus aucuparia
Functional Ecology, 2002Co-Authors: Torbjorn Rage Paulsen, Goran HogstedtAbstract:Summary 1 On the west coast of Norway, Turdus spp. (Thrushes) are important dispersal agents of Sorbus aucuparia L. (Rowan) seeds, and avian and mammalian gut treatment often alters seed germination characteristics. In the present study the effects of avian gut treatment on S. aucuparia seeds are described, with emphasis on subsequent seedling growth. 2 Seeds ingested by Turdus spp. and non-ingested control seeds were sown singly or multiply in soil, in pomes, or in bird droppings. 3 Defecated seeds were ≈9% heavier than control seeds, and seedling growth was faster from defecated seeds than controls. In addition, differences in the rate of seedling emergence were found, with seedlings from ingested seeds appearing first. 4 The increased growth may be due to seedlings emerging earlier from defecated seeds, giving them an extended growth period at a time of increasing day length. 5 We argue that factors such as seedling growth, rate of seedling emergence and seed mass, in addition to percentage seed germination, are important in determining seedling survival.
Torbjorn Rage Paulsen - One of the best experts on this subject based on the ideXlab platform.
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corrigendum to avian gut passage reduces seed exit costs in Sorbus aucuparia rosaceae as measured by a diametral compression test
Functional Plant Biology, 2006Co-Authors: Torbjorn Rage Paulsen, Ommund Lindtjorn, Nils Roar Gjerdet, Goran HogstedtAbstract:Reduced seed exit costs have been suggested to explain advanced seedling emergence and increased seedling growth in Sorbus aucuparia L. (Rosaceae; rowan) following Turdus spp. (Turdidae; thrush) gut passage. In the present study, seed coat tension strength of Turdus merula L. (Turdidae; blackbird) gut-passed and non-ingested control seeds were tested with a diametral compression test. Both maximum load (N) and work (mJ) required for opening the seeds were reduced in gut-passed seeds, although scanning electron microscopy showed no visible differences in seed coat surface structure between treatments. In addition, gut passage increased dry seed weight by 0.64 mg (22%), weight of hydrated seeds by 0.62 mg (16%) and width of hydrated seeds by 0.1 mm (9%). Absorption causing the seed coat to yield more easily to the germinating seedling is proposed as an explanation for the reduction in seed exit costs. For the emerging seedling, the time and force needed to open the seed coat was reduced, thus lowering dispersal and germination costs of S. aucuparia.
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avian gut passage reduces seed exit costs in Sorbus aucuparia rosaceae as measured by a diametral compression test
Functional Plant Biology, 2006Co-Authors: Torbjorn Rage Paulsen, Ommund Lindtjorn, Nils Roar Gjerdet, Goran HogstedtAbstract:Reduced seed exit costs have been suggested to explain advanced seedling emergence and increased seedling growth in Sorbus aucuparia L. (Rosaceae; rowan) following Turdus spp. (Turdidae; thrush) gut passage. In the present study, seed coat tension strength of Turdus merula L. (Turdidae; blackbird) gut-passed and non-ingested control seeds were tested with a diametral compression test. Both maximum load (N) and work (mJ) required for opening the seeds were reduced in gut-passed seeds, although scanning electron microscopy showed no visible differences in seed coat surface structure between treatments. In addition, gut passage increased dry seed weight by 0.64 mg (22%), weight of hydrated seeds by 0.62 mg (16%) and width of hydrated seeds by 0.1 mm (9%). Absorption causing the seed coat to yield more easily to the germinating seedling is proposed as an explanation for the reduction in seed exit costs. For the emerging seedling, the time and force needed to open the seed coat was reduced, thus lowering dispersal and germination costs of S. aucuparia.
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passage through bird guts increases germination rate and seedling growth in Sorbus aucuparia
Functional Ecology, 2002Co-Authors: Torbjorn Rage Paulsen, Goran HogstedtAbstract:Summary 1 On the west coast of Norway, Turdus spp. (Thrushes) are important dispersal agents of Sorbus aucuparia L. (Rowan) seeds, and avian and mammalian gut treatment often alters seed germination characteristics. In the present study the effects of avian gut treatment on S. aucuparia seeds are described, with emphasis on subsequent seedling growth. 2 Seeds ingested by Turdus spp. and non-ingested control seeds were sown singly or multiply in soil, in pomes, or in bird droppings. 3 Defecated seeds were ≈9% heavier than control seeds, and seedling growth was faster from defecated seeds than controls. In addition, differences in the rate of seedling emergence were found, with seedlings from ingested seeds appearing first. 4 The increased growth may be due to seedlings emerging earlier from defecated seeds, giving them an extended growth period at a time of increasing day length. 5 We argue that factors such as seedling growth, rate of seedling emergence and seed mass, in addition to percentage seed germination, are important in determining seedling survival.
Ulf Sperens - One of the best experts on this subject based on the ideXlab platform.
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long term variation in and effects of fertiliser addition on flower fruit and seed production in the tree Sorbus aucuparia rosaceae
Ecography, 1997Co-Authors: Ulf SperensAbstract:In this paper, I present long-term data on reproduction for the tree Sorbus aucuparia. Variation in fruit-set (6 yr) in 22 trees in one population is described and related to flower predation, climate and floral display size. Fruit production is described for 7 yr in eight trees in each of four populations and related to climate. An additional study, application of a mineral fertiliser, was conducted to test if nutrient availability affected flower, fruit and seed production. The descriptive study showed that mean fruit-set differed significantly between individuals and years. The ranges of yearly mean proportion of initiated fruit/flower, mature fruit/initiated fruit and mature fruit/flower were large (12-41%, 2-72% and 0.3-23%, respectively). Predation of flowers was low, 1% on average (range 0.3-2%). Between-year variations in fruit-set were positively correlated (though not significant) with precipitation during the phase of initiation and maturation of fruits, respec
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fruit production in Sorbus aucuparia l rosaceae and pre dispersal seed predation by the apple fruit moth argyresthia conjugella zell
Oecologia, 1997Co-Authors: Ulf SperensAbstract:Variation in fruit production and pre-dispersal seed predation by Argyresthia conjugella was studied in␣four populations of Sorbus aucuparia in northern Sweden.␣The number of infructescences, fruits per infructescence, consumed seeds and developed unattacked seeds per fruit were scored in marked trees from 1984 to 1990. The results showed that the number of fruits produced in each population determined the number of seed predators occurring in the host population, as the yearly number of seed predators was significantly and positively correlated with yearly number of fruits, in all but one population. The seed predators showed a delay in response to variation in number of fruits produced. This lag in response resulted in a large proportion of fruits being attacked and seeds consumed in a bad fruiting year that followed a good fruiting year, and vice versa. The proportion of fruits attacked and seeds consumed was largest in the population showing the greatest between-year variation in fruit production and lowest in the population showing the lowest between-year variation in fruit production. Furthermore, the individuals within the former population were synchronised, while they were not in the latter population. These results contradict one of the possible explanations of mast-seeding, where large synchronised between-year variation is supposed to reduce pre-dispersal seed predation. Instead, differences in attraction of the seed predator to differences in fruit crop size could explain the observed difference in seed predation between the two populations with opposite fruiting patterns. Within each population, irrespective of year, the proportion of fruits attacked and seeds consumed was independent of a tree's fruiting display. Therefore, trees with high fruit production, despite harbouring the largest number of seed predators, produced the largest number of developed seeds in absolute numbers, compared to trees that produced few fruits.
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is fruit and seed production in Sorbus aucuparia l rosaceae pollen limited
Ecoscience, 1996Co-Authors: Ulf SperensAbstract:Abstract:Pollen-limitation to fruit and seed production in a population of Sorbus aucuparia L. was tested in a hand-pollination experiment in northern Sweden. Forty-two trees in one population were used as either experimental (n = 21) or control trees (n = 21). On each experimental tree inflorescences were used for: i) hand-pollination, ii) open pollination, close (5-20 cm) to the hand-pollinated inflorescences, and iii) open pollination, distant (60-120 cm) to the hand-pollinated inflorescences. A positive effect of additional cross-pollen on fruit-flower ratio and seed production in hand-pollinated inflorescences was found. However, the control inflorescence closest to the hand-pollinated inflorescence showed lower fruit-flower ratio and number of seeds per fruit than both the more distant control inflorescence and the hand-pollinated inflorescence. This observation suggests that resources were shifted from the close control inflorescence to the hand-pollinated inflorescence. When experimental and contr...
H P Muhlbach - One of the best experts on this subject based on the ideXlab platform.
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in vitro cultures of Sorbus aucuparia sustain replication of european mountain ash ringspot associated virus emarav
Plant Cell Tissue and Organ Culture, 2014Co-Authors: Dagmar Svensson, Rashida Perveen, Claudia Hirschfeld, J Robel, H P MuhlbachAbstract:The European mountain ash ringspot-associated virus (EMARaV), the type member of the newly established genus Emaravirus, causes the serious ringspot disease in Sorbus aucuparia (S.a.). Since up to now the virus could not be mechanically transmitted to herbaceous host plants, studies on its replication and gene expression strategies are hampered. Therefore, tissue cultures were established from shoots of EMARaV-infected S.a., and long-term replication of EMARaV was analyzed by detection of viral RNA3 through reverse transcription-polymerase chain reaction. EMARaV infection of calli and cell suspension cultures was detectable even 18 months after callus induction. Neither growth characteristics nor morphological appearance of cells and calli were affected by EMARaV-infection. These cultured cells should facilitate the isolation and analysis of virus particles, which was not achieved yet from S.a. leaf tissue.
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first report of european mountain ash ringspot associated virus in Sorbus aucuparia in norway
Plant Disease, 2014Co-Authors: S Von Bargen, J Robel, H P Muhlbach, T Buttner, C ButtnerAbstract:In July 2012, leaf mottle and intensive chlorotic ringspots were observed on urban, forest, or roadside mountain ash trees (Sorbus aucuparia L., rowan) of different ages in Norway during visual inspection of native broadleaf forest tree species. Symptoms resembled those caused by European mountain ash ringspot-associated virus (EMARaV), the type-member of the newly established genus Emaravirus, containing segmented ss(-)RNA and infecting woody host species (2). Leaves of nine out of 30 assessed rowan trees exhibiting characteristic symptoms were sampled in the counties of Nordland and Nord-Trondelag (between 63.511806° and 66.304680°N latitude). Three of them were infested by the potential vector the eriophyid gall mite Phytoptus pyri. EMARaV was detected from total RNA extracts of leaves by reverse transcription-PCR using virus-specific primers amplifying 300 bp of RNA2 and 204 bp of RNA3, respectively (3). PCR fragments were directly sequenced from both ends and submitted to the EMBL database (accession...
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double stranded rna pattern and partial sequence data indicate plant virus infection associated with the ringspot disease of european mountain ash Sorbus aucuparia l
Archives of Virology, 2005Co-Authors: W Benthack, N Mielke, C Buttner, H P MuhlbachAbstract:Double-stranded RNA (dsRNA) has been extracted from tissue of European mountain ash trees (Sorbus aucuparia L.) showing typical ringspot and mottling symptoms on leaves and a gradual decay in general. A characteristic dsRNA pattern was found in leaf samples of symptomatic mountain ash trees from various stands in Germany. Bands of dsRNA molecules of approximately 7 kb, 2.3 kb, 1.5 kb, and 1.3 kb, respectively, were repeatedly detected. By random primed reverse transcription cDNA was synthesised from dsRNA and amplified by degenerate oligonucleotide primed PCR. After TA cloning, the cDNA clones obtained were screened with an enhanced-chemiluminescence-labelled dsRNA probe. Positive clones were further analysed by using them as hybridisation probes in Northern blots of total plant RNA and in Southern hybridisation with genomic DNA from Sorbus aucuparia leaves. From cDNA clones that were found to be specific for dsRNA in Northern analysis, primers were deduced for 5′-RACE analyses and further cloning. Finally, a cDNA fragment of 3,737 bp was obtained, which showed homology to viral proteins, particularly to the RNA-dependent RNA polymerase of members of the family Bunyaviridae, but without high similarity to a known genus. The dsRNA pattern and the sequence information strongly indicate a virus associated with the mountain ash ringspot disease. The putative virus remains still unidentified.