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Achim Hager - One of the best experts on this subject based on the ideXlab platform.
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Elicitor‐induced changes of wall‐bound and secreted peroxidase activities in suspension‐cultured spruce (Picea abies) cells are attenuated by auxins
Physiologia Plantarum, 1998Co-Authors: Ruth Mensen, Achim Hager, Peter SalzerAbstract:In ectomycorrhizae auxins are proposed to attenuate Elicitor-induced defence reactions in the host plant. To examine this hypothesis we compared the Elicitor-induced accumulation of peroxidase isoforms between suspension-cultured spruce (Picea abies [L.] Karst.) cells incubated in media with and without auxins. In spruce cells changes in ionically and covalently wall-bound as well as symplasmic peroxidase (EC 1.11.1.7) activities were observed when Elicitors from the following fungal species were applied: (1) Hebeloma crustuliniforme, an ectomycorrhizal partner of spruce; (2) Suillus variegatus, an ectomycorrhizal fungus incompatible with spruce; (3) Heterobasidion annosum, a spruce pathogen. Activity staining after SDS-PAGE and western blotting showed an accumulation of an ionically wall-bound 38-kDa peroxidase isoform. In addition, two covalently wall-bound isoforms (34 and 53 kDa) that could be released from spruce cell walls by cellulase and pectinase treatment were also induced by Elicitors from these fungi. Moreover, in cells cultured without auxins all the Elicitors triggered a rapid and transient accumulation of ionically wall-bound peroxidases, which reached a maximum activity 48 h after Elicitor application. This early and transient peroxidase accumulation was diminished and delayed in cells cultured in the presence of auxins. In contrast, activity of peroxidases released into the culture medium of spruce cells or into the medium of protoplasts was suppressed by the Elicitors of Hebeloma crustuliniforme. However, this suppression was attenuated by the action of auxins. It is suggested that under natural conditions, in infected spruce roots, the Elicitors of the compatible fungus cause both suppression of the peroxidase (which is secreted to the free space of the roots), and induction of wall-bound and symplasmic peroxidases. On the other hand, auxins synthesized by the fungus could weaken these different Elicitor-mediated effects.
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Differential effect of purified spruce chitinases and beta-1,3-glucanases on the activity of Elicitors from ectomycorrhizal fungi.
Plant physiology, 1997Co-Authors: Peter Salzer, B. Hubner, A. Sirrenberg, Achim HagerAbstract:Two chitinases (EC 3.2.1.14) and two [beta]-1,3-glucanases (EC 3.2.1.39) were purified from the culture medium of spruce (Picea abies [L.] Karst.) cells to study their role in modifying Elicitors, cell walls, growth, and hyphal morphology of ectomycorrhizal fungi. The 36-kD class I chitinase (isoelectric point [pl] 8.0) and the 28-kD chitinase (pl 8.7) decreased the activity of Elicitor preparations from Hebeloma crustuliniforme (Bull. ex Fries.) Quel., Amanita muscaria (L.) Pers., and Suillus variegatus (Sw.: Fr.) O.K., as demonstrated by using the Elicitor-induced extracellular alkalinization in spruce cells as a test system. In addition, chitinases released monomeric products from the walls of these ectomycorrhizal fungi. The [beta]-1,3-glucanases (35 kD, pl 3.7 and 3.9), in contrast, had little influence on the activity of the fungal Elicitors and released only from walls of A. muscaria some polymeric products. Furthermore, chitinases alone and in combination with [beta]-1,3-glucanases had no effect on the growth and morphology of the hyphae. Thus, it is suggested that apoplastic chitinases in the root cortex destroy Elicitors from the ectomycorrhizal fungi without damaging the fungus. By this mechanism the host plant could attenuate the Elicitor signal and adjust its own defense reactions to a level allowing symbiotic interaction.
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Rapid reactions of spruce cells to Elicitors released from the ectomycorrhizal fungus Hebeloma crustuliniforme, and inactivation of these Elicitors by extracellular spruce cell enzymes
Planta, 1996Co-Authors: Peter Salzer, Gerhard Hebe, Andreas Reith, Barbara Zitterell-haid, Harald Stransky, Katja Gaschler, Achim HagerAbstract:Elicitors released from hyphae or cell walls of the ectomycorrhizal fungus Hebeloma crustuliniforme (Bull. ex Fries.) Quel. induced in suspension-cultured cells of Picea abies (L.) Karst. a set of fast reactions: (i) an immediate efflux of Cl− into the medium, followed by a K+ efflux; (ii) an influx of Ca2+ (measured as accumulation of 45Ca2+ in the cells); (iii) a phosphorylation of a 63-kDa protein and dephosphorylation of a 65-kDa protein (detectable by 4 min after Elicitor application); (iv) an alkalinization of the medium, and (v) a transient synthesis of H2O2. The removal of extracellular Ca2+ by EGTA delayed the Elicitor-induced alkalinization. A further reduction of this response could be achieved by TMB-8 an inhibitor of Ca2+ release from intracellular stores. Moreover, the inhibition of protein kinase activity by staurosporine prevented the extracellular alkalinization completely. However, the effectiveness of the Elicitors in inducing the extracellular alkalinization was strongly impaired by constitutively secreted enzymes of spruce cells which cleaved the Elicitors to inactive fragments. It is suggested that in ectomycorrhizae the efficacy of Elicitors released from fungal cell walls is controlled by apoplastic enzymes of the host; the plant itself is able to reduce the activity of fungal Elicitors on their way through the plant cell wall. But those Elicitors which finally reach the plasma membrane of host cells induce reactions that are similar to the early defense reactions in plant-pathogen interactions.
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Effect of auxins and ectomycorrhizal Elicitors on wall-bound proteins and enzymes of spruce [Picea abies (L.) Karst.] cells
Trees, 1993Co-Authors: Peter Sallzer, Achim HagerAbstract:Elicitors of the ectomycorrhizal fungus Hebeloma crustuliniforme and auxins (IAA, NAA and 2,4-D) were tested for their effects on apoplastic proteins and enzymes of suspension cultured cells of Picea abies (L.) Karst. The ectomycorrhizal Elicitor increased the amount of some ionically wall-bound proteins (36, 28, 24, 21 kDa) and decreased the amount of others (61, 22 kDa). The Elicitor triggered an H_2O_2 burst and enhanced the peroxidase (EC 1.11.1.7) activity of the Picea cells by increasing one of the two wall-bound peroxidase isoforms. Auxins significantly suppressed the Elicitor induction of peroxidase but did not influence the Elicitor-triggered H_2O_2 burst. The Elicitors and auxin did not change the amount and the pattern of wall-bound invertase isoforms (EC 3.2.1.26) of spruce cells. However, auxin reduced the uptake of glucose by spruce cells and increased the acidification of the cell culture medium. Since Hebeloma lacks apoplastic invertase as well as a sucrose uptake system, utilization of plant-derived sucrose depends on the apoplastic plant invertase activity. Although the host invertase is constitutive, the fungus might be able to increase this invertase activity within a mycorrhiza by lowering the pH of the interface towards the pH optimum of the enzyme via the action of auxin. This fungus-released hormone could increase the H^+ extrusion of plant cells by activation of the plant membrane H^+-ATPases. Additionally, an auxin-dependent suppression of glucose uptake by cortical root cells could improve the glucose supply for the fungus. Furthermore, the fungal auxin might suppress the Elicitor induced formation of defense enzymes, such as peroxidase.
Peter Salzer - One of the best experts on this subject based on the ideXlab platform.
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Elicitor‐induced changes of wall‐bound and secreted peroxidase activities in suspension‐cultured spruce (Picea abies) cells are attenuated by auxins
Physiologia Plantarum, 1998Co-Authors: Ruth Mensen, Achim Hager, Peter SalzerAbstract:In ectomycorrhizae auxins are proposed to attenuate Elicitor-induced defence reactions in the host plant. To examine this hypothesis we compared the Elicitor-induced accumulation of peroxidase isoforms between suspension-cultured spruce (Picea abies [L.] Karst.) cells incubated in media with and without auxins. In spruce cells changes in ionically and covalently wall-bound as well as symplasmic peroxidase (EC 1.11.1.7) activities were observed when Elicitors from the following fungal species were applied: (1) Hebeloma crustuliniforme, an ectomycorrhizal partner of spruce; (2) Suillus variegatus, an ectomycorrhizal fungus incompatible with spruce; (3) Heterobasidion annosum, a spruce pathogen. Activity staining after SDS-PAGE and western blotting showed an accumulation of an ionically wall-bound 38-kDa peroxidase isoform. In addition, two covalently wall-bound isoforms (34 and 53 kDa) that could be released from spruce cell walls by cellulase and pectinase treatment were also induced by Elicitors from these fungi. Moreover, in cells cultured without auxins all the Elicitors triggered a rapid and transient accumulation of ionically wall-bound peroxidases, which reached a maximum activity 48 h after Elicitor application. This early and transient peroxidase accumulation was diminished and delayed in cells cultured in the presence of auxins. In contrast, activity of peroxidases released into the culture medium of spruce cells or into the medium of protoplasts was suppressed by the Elicitors of Hebeloma crustuliniforme. However, this suppression was attenuated by the action of auxins. It is suggested that under natural conditions, in infected spruce roots, the Elicitors of the compatible fungus cause both suppression of the peroxidase (which is secreted to the free space of the roots), and induction of wall-bound and symplasmic peroxidases. On the other hand, auxins synthesized by the fungus could weaken these different Elicitor-mediated effects.
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Differential effect of purified spruce chitinases and beta-1,3-glucanases on the activity of Elicitors from ectomycorrhizal fungi.
Plant physiology, 1997Co-Authors: Peter Salzer, B. Hubner, A. Sirrenberg, Achim HagerAbstract:Two chitinases (EC 3.2.1.14) and two [beta]-1,3-glucanases (EC 3.2.1.39) were purified from the culture medium of spruce (Picea abies [L.] Karst.) cells to study their role in modifying Elicitors, cell walls, growth, and hyphal morphology of ectomycorrhizal fungi. The 36-kD class I chitinase (isoelectric point [pl] 8.0) and the 28-kD chitinase (pl 8.7) decreased the activity of Elicitor preparations from Hebeloma crustuliniforme (Bull. ex Fries.) Quel., Amanita muscaria (L.) Pers., and Suillus variegatus (Sw.: Fr.) O.K., as demonstrated by using the Elicitor-induced extracellular alkalinization in spruce cells as a test system. In addition, chitinases released monomeric products from the walls of these ectomycorrhizal fungi. The [beta]-1,3-glucanases (35 kD, pl 3.7 and 3.9), in contrast, had little influence on the activity of the fungal Elicitors and released only from walls of A. muscaria some polymeric products. Furthermore, chitinases alone and in combination with [beta]-1,3-glucanases had no effect on the growth and morphology of the hyphae. Thus, it is suggested that apoplastic chitinases in the root cortex destroy Elicitors from the ectomycorrhizal fungi without damaging the fungus. By this mechanism the host plant could attenuate the Elicitor signal and adjust its own defense reactions to a level allowing symbiotic interaction.
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Rapid reactions of spruce cells to Elicitors released from the ectomycorrhizal fungus Hebeloma crustuliniforme, and inactivation of these Elicitors by extracellular spruce cell enzymes
Planta, 1996Co-Authors: Peter Salzer, Gerhard Hebe, Andreas Reith, Barbara Zitterell-haid, Harald Stransky, Katja Gaschler, Achim HagerAbstract:Elicitors released from hyphae or cell walls of the ectomycorrhizal fungus Hebeloma crustuliniforme (Bull. ex Fries.) Quel. induced in suspension-cultured cells of Picea abies (L.) Karst. a set of fast reactions: (i) an immediate efflux of Cl− into the medium, followed by a K+ efflux; (ii) an influx of Ca2+ (measured as accumulation of 45Ca2+ in the cells); (iii) a phosphorylation of a 63-kDa protein and dephosphorylation of a 65-kDa protein (detectable by 4 min after Elicitor application); (iv) an alkalinization of the medium, and (v) a transient synthesis of H2O2. The removal of extracellular Ca2+ by EGTA delayed the Elicitor-induced alkalinization. A further reduction of this response could be achieved by TMB-8 an inhibitor of Ca2+ release from intracellular stores. Moreover, the inhibition of protein kinase activity by staurosporine prevented the extracellular alkalinization completely. However, the effectiveness of the Elicitors in inducing the extracellular alkalinization was strongly impaired by constitutively secreted enzymes of spruce cells which cleaved the Elicitors to inactive fragments. It is suggested that in ectomycorrhizae the efficacy of Elicitors released from fungal cell walls is controlled by apoplastic enzymes of the host; the plant itself is able to reduce the activity of fungal Elicitors on their way through the plant cell wall. But those Elicitors which finally reach the plasma membrane of host cells induce reactions that are similar to the early defense reactions in plant-pathogen interactions.
Jianyong Wu - One of the best experts on this subject based on the ideXlab platform.
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Elicitor induced rosmarinic acid accumulation and secondary metabolism enzyme activities in salvia miltiorrhiza hairy roots
Plant Science, 2006Co-Authors: Janet Ng, Jianyong WuAbstract:Abstract This work is to examine the rosmarinic acid (RA) accumulation and related secondary metabolism enzyme activities of Salvia miltiorrhiza Bunge (Lamiacae) hairy roots in response to a biotic Elicitor, yeast extract (YE) and an abiotic Elicitor, Ag+. RA accumulation as well as total phenolic content of the hairy roots was increased by both Elicitors, but more significantly by YE. Preceding the Elicitor-induced RA accumulation, there was a notable rise in the tyrosine aminotransferase (TAT) activity but a rapid drop in the phenylalanine ammonia-lyase (PAL) activity of roots. All Elicitor effects were dependent on the Elicitor dose, maximized with YE at 200 mg/L and Ag+ at 15 μM. The results showed that the Elicitor-induced biosynthesis of RA and phenolic compounds in the S. miltiorrhiza hairy roots was correlated with the TAT but not the PAL activity.
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tanshinone production and isoprenoid pathways in salvia miltiorrhiza hairy roots induced by ag and yeast Elicitor
Plant Science, 2005Co-Authors: Xiuchun Ge, Jianyong WuAbstract:This work examined the accumulation of diterpenoid tanshinones and related secondary metabolism pathways in hairy root cultures of Salvia miltiorrhiza Bunge (Lamiacae) induced by a biotic Elicitor, the carbohydrate fraction of yeast extract (YE, 100 m gm L 1 ), and an abiotic Elicitor, Ag + (30 mM). The activity of 3-hydroxy-3-methylglutaryl CoA redutase (HMGR) was only stimulated by Ag + , and 1-deoxyD-xylulose 5-phosphate synthase (DXS) was stimulated by both, but more strongly by YE. While the non-MVA pathway inhibitor fosmidomycin inhibited the tanshinone accumulation induced by both Elicitors, the MVA-pathway inhibitor mevinolin only suppressed the Ag-induced tanshinone accumulation. The results suggest that the tanshinone accumulation induced by the two Elicitors was mainly synthesized via the non-MVA pathway (DXS activity), but could depend on crosstalk between the MVA and non-MVA pathways. Furthermore, the pretreatment of hairy roots with Ag + for 24–48 h potentiated the YE-induced tanshinone production and DXS activity.
Thomas Boller - One of the best experts on this subject based on the ideXlab platform.
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THE APPARENT TURNOVER OF 1-AMINOCYCLOPROPANE-1-CARBOXYLATE SYNTHASE IN TOMATO CELLS IS REGULATED BY PROTEIN PHOSPHORYLATION AND DEPHOSPHORYLATION
Plant Physiology, 1994Co-Authors: Pietro Spanu, Debora G Grosskopf, Georg Felix, Thomas BollerAbstract:In suspension-cultured cells of tomato (Lycopersicon esculentum Mill.), the activity of 1-aminocyclopropane-1-carboxylate synthase (ACC-S) rapidly increases in response to fungal Elicitors. The effect of inhibitors of protein kinases and protein phosphatases on the regulation of ACC-S was studied. K-252a, an inhibitor of protein kinases, prevented induction of the enzyme by Elicitors and promoted its apparent turnover in Elicitor-stimulated cells, causing a 50% loss of activity within 4 to 8 min in both the presence and absence of cycloheximide. Calyculin A, an inhibitor of protein phosphatases, caused a rapid increase of ACC-S in the absence of Elicitors and an immediate acceleration of the rate of ACC-S increase in Elicitor-stimulated cells. In the presence of cycloheximide there was no such increase, indicating that the effect depended on protein synthesis. Cordycepin, an inhibitor of mRNA synthesis, did not prevent the Elicitor-induced increase in ACC-S activity but strongly reduced the K-252a-induced decay and the calyculin A-induced increase of its activity. In vitro, ACC-S activity was not affected by K-252a and calyculin A or by treatments with protein phosphatases. These results suggest that protein phosphorylation/dephosphorylation is involved in the regulation of ACC-S, not by regulating the catalytic activity itself but by controlling the rate of turnover of the enzyme.
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the protein phosphatase inhibitor calyculin a mimics Elicitor action in plant cells and induces rapid hyperphosphorylation of specific proteins as revealed by pulse labeling with 33p phosphate
Proceedings of the National Academy of Sciences of the United States of America, 1994Co-Authors: Georg Felix, Martin Regenass, Pietro Spanu, Thomas BollerAbstract:Suspension-cultured tomato cells react to microbial signals, so-called Elicitors, with rapid alkalinization of the growth medium and increased biosynthesis of the stress hormone ethylene. These responses to Elicitors can be blocked by staurosporine and K-252a, two specific inhibitors of protein kinases. Here we show that calyculin A, a potent inhibitor of protein phosphatases, mimics the action of Elicitors and, at nanomolar concentrations, induces medium alkalinization as well as a strong increase in the activity of 1-aminocyclopropane-1-carboxylate synthase, the key enzyme of ethylene biosynthesis. Both responses were strongly inhibited by K-252a, and calyculin A induced both responses more rapidly than did a fungal Elicitor, xylanase. For example, the lag phase for medium alkalinization was only 0.2-0.4 min for calyculin A, compared with 2 min for xylanase. To study changes in the dynamics of protein phosphorylation, cells were labeled with 30-sec pulses of [33P]orthophosphate. Calyculin A strongly increased phosphorylation of several polypeptide bands within 40 sec of treatment. The same phosphorylated bands also appeared in response to xylanase, but only after a lag phase of 2-3 min. These results show that the protein phosphatase inhibitor calyculin A leads to rapid hyperphosphorylation of specific proteins in cultured cells and indicate that Elicitor action could be based on inhibition of a protein phosphatase as well as on activation of a protein kinase.
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Rapid changes of protein phosphorylation are involved in transduction of the Elicitor signal in plant cells
Proceedings of the National Academy of Sciences of the United States of America, 1991Co-Authors: Georg Felix, Debora G Grosskopf, Martin Regenass, Thomas BollerAbstract:Abstract Plant cells have an acute sense for pathogen-derived chemical stimuli, so-called Elicitors, which induce the plant's defense response. To investigate the molecular basis of chemosensory transduction, Elicitor-treated tomato cells were labeled with 1-min pulses of [32P] phosphate. This technique revealed drastic changes in protein phosphorylation in vivo within minutes of stimulation. The protein kinase inhibitors K-252a and staurosporine completely prevented these Elicitor-induced changes in protein phosphorylation. They also blocked two early biochemical responses to Elicitors, extracellular alkalinization and biosynthesis of ethylene. The ability of K-252a, staurosporine, and benzoylated staurosporine derivatives to inhibit Elicitor responses in vivo correlated with their ability to inhibit tomato microsomal protein kinase in vitro. When K-252a was given to elicited cells 1 min after the[32] phosphate, the radioactivity in certain newly labeled phosphoprotein bands disappeared again within minutes. This correlated with an arrest of alkalinization within minutes when K-252a was applied in midcourse of elicitation. These data show that phosphorylation of protein substrates by K-252a-sensitive protein kinases is essential for transduction of Elicitor signals in plant cells and that continuous phosphorylation of these proteins is required to maintain the elicited state.
Myungsuk Choi - One of the best experts on this subject based on the ideXlab platform.
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effects of Elicitors on scopolamine production of scopolia parviflora nakai adventitious roots in bubble column bioreactor
The Korean Journal of Medicinal Crop Science, 2004Co-Authors: Heeyoung Jung, Seung Mi Kang, Youngmin Kang, Dongjin Park, Myungsuk ChoiAbstract:Scopolamine and hyoscyamine are important anticholinergic compounds. To increase the productivity, we have selected various Elicitors and developed culture system using a bubble column bioreactor (BCB). As the same manner of elicitation in flask cultures, the Elicitors were introduced into BCB cultures and the productivity was investigated. Except the bacterial Elicitor of Staphyllococcus aureus, the Elicitors inhibited hyoscyamine production. In scopolamine production, the Elicitors revealed different responses from the results obtained in flask cultures. The Elicitors of KCl and Candida albicans less increased the production than flask cultures. However, methyl jasmonate and S. aureus showed stronger positive effects on tropane alkaloid production. In particular, S. aureus was the most effective Elicitor on scopolamine production and the Elicitor resulted in the highly increased production, approximately 10 times higher than the control culture.
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enhanced production of scopolamine by bacterial Elicitors in adventitious hairy root cultures of scopolia parviflora
Enzyme and Microbial Technology, 2003Co-Authors: Heeyoung Jung, Seung Mi Kang, Youngmin Kang, Minjung Kang, Jungdong Bahk, Jaekyung Yang, Myungsuk ChoiAbstract:In an attempt to increase productivity, the effect of elicitation on tropane alkaloids (TA) biosynthesis was studied in adventitious hairy root cultures of Scopolia parviflora. Two Gram-positive strains and one Gram-negative strain of bacteria were used as biotic Elicitors. The raw bacterial Elicitors affected the tropane alkaloid profile by increasing the scopolamine concentration, while the autoclaved bacterial Elicitors produced similar effects on the control. The conversion ratio of hyoscyamine to scopolamine was increased following elicitation using raw bacterial Elicitors. The bacterial Elicitor inhibited the expression of H6H (hyoscyamine 6β-hydoxylase) whereas the expression of PMT (putrescine N-methyltransferase) was raised by elicitation. These results have important implications for the large-scale production of tropane alkaloids.
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selection of optimal biotic Elicitor on tropane alkaloid production of hairy roots in scopolia parviflora nakai
The Korean Journal of Medicinal Crop Science, 2003Co-Authors: Heeyoung Jung, Seung Mi Kang, Youngmin Kang, Jaekyung Yang, Younggwan Chung, Myungsuk ChoiAbstract:ScopoIamine and hyoscyamine which belong to tropane alkaloids are the pharmaceutically valuable anticholinergic drugs. In order to increase the productivities, the effects of elicitation were investigated during hairy root cultures of Scopolia. parviflora. Biotic Elicitors originated from 3 fungi and 1 yeast were prepared as homogenate and supernatant and added to 3-week-old cultures. Both of homogenate and supernatant of Candida albicans Elicitors increased the scopolamine production. The production of hyoscyamine was enhanced by homogenate of Fusarium solani and supernatant of C. albicans. Most of the other fungal Elicitors were also improved on the tropane alkaloid production compared to non-treatment. Among the Elicitors tested, C. albicans was proved the optimal biotic Elicitor on tropane alkaloids production. These results will be served mass production of tropane alkaloids by large-scale production.
