Plant immune responses triggered upon recognition of microbe-associated molecular patterns (MAMPs... more Plant immune responses triggered upon recognition of microbe-associated molecular patterns (MAMPs) typically restrict pathogen growth without a host cell death response. We isolated two Arabidopsis mutants, derived from accession Col-0, that activated cell death upon inoculation with nonadapted fungal pathogens. Notably, the mutants triggered cell death also when treated with bacterial MAMPs such as flg22. Positional cloning identified NSL1 (Necrotic Spotted Lesion 1) as a responsible gene for the phenotype of the two mutants, whereas nsl1 mutations of the accession No-0 resulted in necrotic lesion formation without pathogen inoculation. NSL1 encodes a protein of unknown function containing a putative membrane-attack complex/perforin (MACPF) domain. The application of flg22 increased salicylic acid (SA) accumulation in the nsl1 plants derived from Col-0, while depletion of isochorismate synthase 1 repressed flg22-inducible lesion formation, indicating that elevated SA is needed for the cell death response. nsl1 plants of Col-0 responded to flg22 treatment with an RBOHD-dependent oxidative burst, but this response was dispensable for the nsl1-dependent cell death. Surprisingly, loss-of-function mutations in PEN2, involved in the metabolism of tryptophan (Trp)-derived indole glucosinolates, suppressed the flg22-induced and nsl1-dependent cell death. Moreover, the increased accumulation of SA in the nsl1 plants was abrogated by blocking Trp-derived secondary metabolite biosynthesis, whereas the nsl1-dependent hyperaccumulation of PEN2-dependent compounds was unaffected when the SA biosynthesis pathway was blocked. Collectively, these findings suggest that MAMP-triggered immunity activates a genetically programmed cell death in the absence of the functional MACPF domain protein NSL1 via Trp-derived secondary metabolite-mediated activation of the SA pathway.
In this study, proteomic and metabolomic changes in leaves and roots of two barley (Hordeum vulga... more In this study, proteomic and metabolomic changes in leaves and roots of two barley (Hordeum vulgare L.) genotypes, with contrasting drought tolerance, subjected to water deficit were investigated. Our two-dimensional electrophoresis (2D-PAGE) combined with matrix-assisted laser desorption time of flight mass spectrometry (MALDI-TOF and MALDI-TOF/TOF) analyses revealed 121 drought-responsive proteins in leaves and 182 in roots of both genotypes. Many of the identified drought-responsive proteins were associated with processes that are typically severely affected during water deficit, including photosynthesis and carbon metabolism. However, the highest number of identified leaf and root proteins represented general defense mechanisms. In addition, changes in the accumulation of proteins that represent processes formerly unassociated with drought response, e.g., phenylpropanoid metabolism, were also identified. Our tandem gas chromatography - time of flight mass spectrometry (GC/MS TOF) analyses revealed approximately 100 drought-affected low molecular weight compounds representing various metabolite types with amino acids being the most affected metabolite class. We compared the results from proteomic and metabolomic analyses to search for existing relationship between these two levels of molecular organization. We also uncovered organ specificity of the observed changes and revealed differences in the response to water deficit of drought susceptible and tolerant barley lines. Particularly, our results indicated that several of identified proteins and metabolites whose accumulation levels were increased with drought in the analyzed susceptible barley variety revealed elevated constitutive accumulation levels in the drought-resistant line. This may suggest that constitutive biochemical predisposition represents a better drought tolerance mechanism than inducible responses.
Qualitative and quantitative composition of flavonoid and isoflavonoid glycosides as well as free... more Qualitative and quantitative composition of flavonoid and isoflavonoid glycosides as well as free aglycones in lupin seedlings (roots and aerial parts) grown under different light conditions or responding to infection with Pleiochaeta setosa, a fungus causing brown leaf spot, were monitored by liquid chromatography with UV and/or mass spectrometric detection. Both physical and biotic factors affected flavonoid and isoflavonoid levels in lupin tissues. Fungal infection evoked significant increase in the amounts of genistein, 2 -hydroxygenistein, and their prenylated derivatives that are thought to function as lupin phytoalexins. Effect on quantitative changes of glycosylated flavonoids and isoflavonoids in the roots and aerial parts was less significant. Moreover, different light conditions applied during seedling growth caused relative changes of flavonoid and isoflavonoid conjugates composition, especially in the leaves of white lupin plants. The chemical structures of flavonoid and isoflavonoid conjugates present in Lupinus angustifolius were elucidated. In addition to genistein and 2 -hydroxygenistein glycosides, flavonol conjugates were identified in leaves,
Liquid chromatography with ultraviolet and mass spectrometric detection was applied to monitor ch... more Liquid chromatography with ultraviolet and mass spectrometric detection was applied to monitor changes in profiles of isoflavonoid glycosides and free isoflavonoid aglycones in Lupinus albus L. Four isoflavonoid aglycones, fourteen isoflavonoid glycosides, four flavonol glycosides and flavone glycoside were identified in lupin tissue after LC/ESI/MS analyses. An elicitor preparation from purified yeast cell wall was used to inject the shoots of 3-week old seedlings or to infiltrate the cut lupin leaves. Qualitative and quantitative changes of isoflavonoids were measured at different time points after elicitation. In elicited lupin seedlings increased amounts of prenylated isoflavone aglycones were identified. The concentrations of glycosidic conjugates of isoflavones present in plant tissue were less affected.
Liquid chromatography with ultraviolet and mass spectrometric detection was applied to monitor ch... more Liquid chromatography with ultraviolet and mass spectrometric detection was applied to monitor changes in profiles of isoflavonoid glycosides and free isoflavonoid aglycones in Lupinus albus L. Four isoflavonoid aglycones, fourteen isoflavonoid glycosides, four flavonol glycosides and flavone glycoside were identified in lupin tissue after LC/ESI/MS analyses. An elicitor preparation from purified yeast cell wall was used to inject the shoots of 3-week old seedlings or to infiltrate the cut lupin leaves. Qualitative and quantitative changes of isoflavonoids were measured at different time points after elicitation. In elicited lupin seedlings increased amounts of prenylated isoflavone aglycones were identified. The concentrations of glycosidic conjugates of isoflavones present in plant tissue were less affected.
MYB34, MYB51 and MYB122 transcription factors are known as decisive regulators of indolic glucosi... more MYB34, MYB51 and MYB122 transcription factors are known as decisive regulators of indolic glucosinolate (IG) biosynthesis with a strong impact on expression of genes encoding CYP79B2 and CYP79B3 enzymes that redundantly convert tryptophan to indole-3-acetaldoxime (IAOx). This intermediate represents a branching point for IG-biosynthesis, and pathways leading to camalexin and indole-carboxylic acids (ICA). Here we investigated how these MYBs affect the pathogen triggered Trp-metabolism. Our experiments indicated that these three MYBs affect not only IG-production, but also constitutive biosynthesis of other IAOx-derived metabolites. Strikingly, the PENETRATION2 (PEN2)-dependent IG-metabolism products, which are absent in myb34/51/122 and pen2 mutants, were indispensable for full flg22-mediated induction of other IAOx-derived compounds. However, gene induction and accumulation of ICAs and camalexin upon pathogen infection was not compromised in myb34/51/122 plants, despite strongly reduced IG levels. Hence, in comparison to cyp79B2/B3, which lacks all IAOx-derived metabolites, we found myb34/51/122 as an ideal tool to analyse IG contribution to resistance against the necrotrophic fungal pathogen Plectosphaerella cucumerina. The susceptibility of myb34/51/122 was similar to that of pen2, but much lower than susceptibility of cyp79B2/B3 indicating that MYBs studied in this work contribute to resistance towards P. cucumerina exclusively through IG-biosynthesis and that PEN2 is the main leaf myrosinase activating IGs in response to microbial pathogens.
Flavonoid glycosides constitute important group of plant secondary metabolites. This class of nat... more Flavonoid glycosides constitute important group of plant secondary metabolites. This class of natural products play significant role in different physiological processes. A new methodological approach where mass spectrometric techniques are applied to structural studies of this class of compounds is presented. Four flavonoid O-monoglycosides and one C-monoglycoside were isolated from green parts of lupin (Lupinus luteus L.). Several different mass spectrometric techniques were applied to structural elucidation of isolated compounds. Desorption ionization mass spectrometry was used for registration of mass spectra of intact and derivatized (permethylated) flavonoid glycosides. In some cases electron impact mass spectra of permethylated compounds were also recorded. Methylated samples after methanolysis and further derivatization of free hydroxyl groups (methylation or acetylation) were analyzed with gas chromatography-mass spectrometry. Combined information drawn from the registered mass spectra enabled us to define molecular mass, structure of aglycones and sugars, and positions of glycosidic bonds on the aglycon. Structures of four flavonoid monoglycosides were elucidated as follows: genistein 7-O-glucoside (1), genistein 4'-O-glucoside (2), 2'-hydroxygenistein 7-O-glucoside (3), and apigenin or genistein 8-C-glycoside (5). For the fourth O-glycoside (4) only molecular mass and masses of the aglycone and sugar were estimated.
Arabidopsis PENETRATION (PEN) genes quantitatively contribute to the execution of different forms... more Arabidopsis PENETRATION (PEN) genes quantitatively contribute to the execution of different forms of plant immunity upon challenge with diverse leaf pathogens. PEN3 encodes a plasma membrane-resident pleiotropic drug resistance-type ATP-binding cassette transporter and is thought to act in a pathogen-inducible and PEN2 myrosinase-dependent metabolic pathway in extracellular defense. This metabolic pathway directs the intracellular biosynthesis and activation of tryptophan (Trp)-derived indole glucosinolates for subsequent PEN3-mediated efflux across the plasma membrane at pathogen contact sites. However, PEN3 functions also in abiotic stress responses to cadmium and indole-3-butyric acid (IBA)-mediated auxin homeostasis in roots, raising the possibility that PEN3 exports multiple functionally unrelated substrates. Here we describe the isolation of a pen3 allele, designated pen3-5, which encodes a dysfunctional protein that accumulates in planta like wild-type PEN3. The specific muta...
I. II. III. IV. V. VI. References SUMMARY: Plant secondary metabolites carry out numerous functio... more I. II. III. IV. V. VI. References SUMMARY: Plant secondary metabolites carry out numerous functions in interactions between plants and a broad range of other organisms. Experimental evidence strongly supports the indispensable contribution of many constitutive and pathogen-inducible phytochemicals to plant innate immunity. Extensive studies on model plant species, particularly Arabidopsis thaliana, have brought significant advances in our understanding of the molecular mechanisms underpinning pathogen-triggered biosynthesis and activation of defensive secondary metabolites. However, despite the proven significance of secondary metabolites in plant response to pathogenic microorganisms, little is known about the precise mechanisms underlying their contribution to plant immunity. This insufficiency concerns information on the dynamics of cellular and subcellular localization of defensive phytochemicals during the encounters with microbial pathogens and precise knowledge on their mode of action. As many secondary metabolites are characterized by their in vitro antimicrobial activity, these compounds were commonly considered to function in plant defense as in planta antibiotics. Strikingly, recent experimental evidence suggests that at least some of these compounds alternatively may be involved in controlling several immune responses that are evolutionarily conserved in the plant kingdom, including callose deposition and programmed cell death.
Qualitative and quantitative composition of flavonoid and isoflavonoid glycosides as well as free... more Qualitative and quantitative composition of flavonoid and isoflavonoid glycosides as well as free aglycones in lupin seedlings (roots and aerial parts) grown under different light conditions or responding to infection with Pleiochaeta setosa, a fungus causing brown leaf spot, were monitored by liquid chromatography with UV and/or mass spectrometric detection. Both physical and biotic factors affected flavonoid and isoflavonoid levels in lupin tissues. Fungal infection evoked significant increase in the amounts of genistein, 2 -hydroxygenistein, and their prenylated derivatives that are thought to function as lupin phytoalexins. Effect on quantitative changes of glycosylated flavonoids and isoflavonoids in the roots and aerial parts was less significant. Moreover, different light conditions applied during seedling growth caused relative changes of flavonoid and isoflavonoid conjugates composition, especially in the leaves of white lupin plants. The chemical structures of flavonoid and isoflavonoid conjugates present in Lupinus angustifolius were elucidated. In addition to genistein and 2 -hydroxygenistein glycosides, flavonol conjugates were identified in leaves,
A total of eleven alkali-released, aromatic compounds were identified by HPLC, MS and NMR analyse... more A total of eleven alkali-released, aromatic compounds were identified by HPLC, MS and NMR analyses in cell wall extracts from Arabidopsis thaliana roots. Nine of them together constituted the three complete series of 4-hydroxy-, 4-hydroxy-3-methoxy, and 4hydroxy-3,5-dimethoxy-substituted benzaldehydes, benzoic acids and cinnamic acids. The other two were indolic metabolites: indole-3-carboxylic acid and indole-3-carbaldehyde. Qualitatively similar, but quantitatively distinct profiles were obtained using cell-wall extracts from A. thaliana leaves. Several of these compounds, particularly indole-3-carboxylic acid, 4-hydroxybenzoic acid and all four aldehydes, increased considerably in concentration upon infection of roots with Pythium sylvaticum, as did at least some of them upon infection of leaves with Pseudomonas syringae pv tomato. Comparison of these results with analogous data on a variety of different plant species suggests a remarkable structural uniformity among the majority of constitutive as well as infectioninduced, aromatic cell wall-bound compounds throughout the entire plant kingdom-in sharp contrast to the highly speciesspecific, chemically highly divers bouquets of soluble aromatic metabolites. #
Plant immune responses triggered upon recognition of microbe-associated molecular patterns (MAMPs... more Plant immune responses triggered upon recognition of microbe-associated molecular patterns (MAMPs) typically restrict pathogen growth without a host cell death response. We isolated two Arabidopsis mutants, derived from accession Col-0, that activated cell death upon inoculation with nonadapted fungal pathogens. Notably, the mutants triggered cell death also when treated with bacterial MAMPs such as flg22. Positional cloning identified NSL1 (Necrotic Spotted Lesion 1) as a responsible gene for the phenotype of the two mutants, whereas nsl1 mutations of the accession No-0 resulted in necrotic lesion formation without pathogen inoculation. NSL1 encodes a protein of unknown function containing a putative membrane-attack complex/perforin (MACPF) domain. The application of flg22 increased salicylic acid (SA) accumulation in the nsl1 plants derived from Col-0, while depletion of isochorismate synthase 1 repressed flg22-inducible lesion formation, indicating that elevated SA is needed for the cell death response. nsl1 plants of Col-0 responded to flg22 treatment with an RBOHD-dependent oxidative burst, but this response was dispensable for the nsl1-dependent cell death. Surprisingly, loss-of-function mutations in PEN2, involved in the metabolism of tryptophan (Trp)-derived indole glucosinolates, suppressed the flg22-induced and nsl1-dependent cell death. Moreover, the increased accumulation of SA in the nsl1 plants was abrogated by blocking Trp-derived secondary metabolite biosynthesis, whereas the nsl1-dependent hyperaccumulation of PEN2-dependent compounds was unaffected when the SA biosynthesis pathway was blocked. Collectively, these findings suggest that MAMP-triggered immunity activates a genetically programmed cell death in the absence of the functional MACPF domain protein NSL1 via Trp-derived secondary metabolite-mediated activation of the SA pathway.
In this study, proteomic and metabolomic changes in leaves and roots of two barley (Hordeum vulga... more In this study, proteomic and metabolomic changes in leaves and roots of two barley (Hordeum vulgare L.) genotypes, with contrasting drought tolerance, subjected to water deficit were investigated. Our two-dimensional electrophoresis (2D-PAGE) combined with matrix-assisted laser desorption time of flight mass spectrometry (MALDI-TOF and MALDI-TOF/TOF) analyses revealed 121 drought-responsive proteins in leaves and 182 in roots of both genotypes. Many of the identified drought-responsive proteins were associated with processes that are typically severely affected during water deficit, including photosynthesis and carbon metabolism. However, the highest number of identified leaf and root proteins represented general defense mechanisms. In addition, changes in the accumulation of proteins that represent processes formerly unassociated with drought response, e.g., phenylpropanoid metabolism, were also identified. Our tandem gas chromatography - time of flight mass spectrometry (GC/MS TOF) analyses revealed approximately 100 drought-affected low molecular weight compounds representing various metabolite types with amino acids being the most affected metabolite class. We compared the results from proteomic and metabolomic analyses to search for existing relationship between these two levels of molecular organization. We also uncovered organ specificity of the observed changes and revealed differences in the response to water deficit of drought susceptible and tolerant barley lines. Particularly, our results indicated that several of identified proteins and metabolites whose accumulation levels were increased with drought in the analyzed susceptible barley variety revealed elevated constitutive accumulation levels in the drought-resistant line. This may suggest that constitutive biochemical predisposition represents a better drought tolerance mechanism than inducible responses.
Qualitative and quantitative composition of flavonoid and isoflavonoid glycosides as well as free... more Qualitative and quantitative composition of flavonoid and isoflavonoid glycosides as well as free aglycones in lupin seedlings (roots and aerial parts) grown under different light conditions or responding to infection with Pleiochaeta setosa, a fungus causing brown leaf spot, were monitored by liquid chromatography with UV and/or mass spectrometric detection. Both physical and biotic factors affected flavonoid and isoflavonoid levels in lupin tissues. Fungal infection evoked significant increase in the amounts of genistein, 2 -hydroxygenistein, and their prenylated derivatives that are thought to function as lupin phytoalexins. Effect on quantitative changes of glycosylated flavonoids and isoflavonoids in the roots and aerial parts was less significant. Moreover, different light conditions applied during seedling growth caused relative changes of flavonoid and isoflavonoid conjugates composition, especially in the leaves of white lupin plants. The chemical structures of flavonoid and isoflavonoid conjugates present in Lupinus angustifolius were elucidated. In addition to genistein and 2 -hydroxygenistein glycosides, flavonol conjugates were identified in leaves,
Liquid chromatography with ultraviolet and mass spectrometric detection was applied to monitor ch... more Liquid chromatography with ultraviolet and mass spectrometric detection was applied to monitor changes in profiles of isoflavonoid glycosides and free isoflavonoid aglycones in Lupinus albus L. Four isoflavonoid aglycones, fourteen isoflavonoid glycosides, four flavonol glycosides and flavone glycoside were identified in lupin tissue after LC/ESI/MS analyses. An elicitor preparation from purified yeast cell wall was used to inject the shoots of 3-week old seedlings or to infiltrate the cut lupin leaves. Qualitative and quantitative changes of isoflavonoids were measured at different time points after elicitation. In elicited lupin seedlings increased amounts of prenylated isoflavone aglycones were identified. The concentrations of glycosidic conjugates of isoflavones present in plant tissue were less affected.
Liquid chromatography with ultraviolet and mass spectrometric detection was applied to monitor ch... more Liquid chromatography with ultraviolet and mass spectrometric detection was applied to monitor changes in profiles of isoflavonoid glycosides and free isoflavonoid aglycones in Lupinus albus L. Four isoflavonoid aglycones, fourteen isoflavonoid glycosides, four flavonol glycosides and flavone glycoside were identified in lupin tissue after LC/ESI/MS analyses. An elicitor preparation from purified yeast cell wall was used to inject the shoots of 3-week old seedlings or to infiltrate the cut lupin leaves. Qualitative and quantitative changes of isoflavonoids were measured at different time points after elicitation. In elicited lupin seedlings increased amounts of prenylated isoflavone aglycones were identified. The concentrations of glycosidic conjugates of isoflavones present in plant tissue were less affected.
MYB34, MYB51 and MYB122 transcription factors are known as decisive regulators of indolic glucosi... more MYB34, MYB51 and MYB122 transcription factors are known as decisive regulators of indolic glucosinolate (IG) biosynthesis with a strong impact on expression of genes encoding CYP79B2 and CYP79B3 enzymes that redundantly convert tryptophan to indole-3-acetaldoxime (IAOx). This intermediate represents a branching point for IG-biosynthesis, and pathways leading to camalexin and indole-carboxylic acids (ICA). Here we investigated how these MYBs affect the pathogen triggered Trp-metabolism. Our experiments indicated that these three MYBs affect not only IG-production, but also constitutive biosynthesis of other IAOx-derived metabolites. Strikingly, the PENETRATION2 (PEN2)-dependent IG-metabolism products, which are absent in myb34/51/122 and pen2 mutants, were indispensable for full flg22-mediated induction of other IAOx-derived compounds. However, gene induction and accumulation of ICAs and camalexin upon pathogen infection was not compromised in myb34/51/122 plants, despite strongly reduced IG levels. Hence, in comparison to cyp79B2/B3, which lacks all IAOx-derived metabolites, we found myb34/51/122 as an ideal tool to analyse IG contribution to resistance against the necrotrophic fungal pathogen Plectosphaerella cucumerina. The susceptibility of myb34/51/122 was similar to that of pen2, but much lower than susceptibility of cyp79B2/B3 indicating that MYBs studied in this work contribute to resistance towards P. cucumerina exclusively through IG-biosynthesis and that PEN2 is the main leaf myrosinase activating IGs in response to microbial pathogens.
Flavonoid glycosides constitute important group of plant secondary metabolites. This class of nat... more Flavonoid glycosides constitute important group of plant secondary metabolites. This class of natural products play significant role in different physiological processes. A new methodological approach where mass spectrometric techniques are applied to structural studies of this class of compounds is presented. Four flavonoid O-monoglycosides and one C-monoglycoside were isolated from green parts of lupin (Lupinus luteus L.). Several different mass spectrometric techniques were applied to structural elucidation of isolated compounds. Desorption ionization mass spectrometry was used for registration of mass spectra of intact and derivatized (permethylated) flavonoid glycosides. In some cases electron impact mass spectra of permethylated compounds were also recorded. Methylated samples after methanolysis and further derivatization of free hydroxyl groups (methylation or acetylation) were analyzed with gas chromatography-mass spectrometry. Combined information drawn from the registered mass spectra enabled us to define molecular mass, structure of aglycones and sugars, and positions of glycosidic bonds on the aglycon. Structures of four flavonoid monoglycosides were elucidated as follows: genistein 7-O-glucoside (1), genistein 4'-O-glucoside (2), 2'-hydroxygenistein 7-O-glucoside (3), and apigenin or genistein 8-C-glycoside (5). For the fourth O-glycoside (4) only molecular mass and masses of the aglycone and sugar were estimated.
Arabidopsis PENETRATION (PEN) genes quantitatively contribute to the execution of different forms... more Arabidopsis PENETRATION (PEN) genes quantitatively contribute to the execution of different forms of plant immunity upon challenge with diverse leaf pathogens. PEN3 encodes a plasma membrane-resident pleiotropic drug resistance-type ATP-binding cassette transporter and is thought to act in a pathogen-inducible and PEN2 myrosinase-dependent metabolic pathway in extracellular defense. This metabolic pathway directs the intracellular biosynthesis and activation of tryptophan (Trp)-derived indole glucosinolates for subsequent PEN3-mediated efflux across the plasma membrane at pathogen contact sites. However, PEN3 functions also in abiotic stress responses to cadmium and indole-3-butyric acid (IBA)-mediated auxin homeostasis in roots, raising the possibility that PEN3 exports multiple functionally unrelated substrates. Here we describe the isolation of a pen3 allele, designated pen3-5, which encodes a dysfunctional protein that accumulates in planta like wild-type PEN3. The specific muta...
I. II. III. IV. V. VI. References SUMMARY: Plant secondary metabolites carry out numerous functio... more I. II. III. IV. V. VI. References SUMMARY: Plant secondary metabolites carry out numerous functions in interactions between plants and a broad range of other organisms. Experimental evidence strongly supports the indispensable contribution of many constitutive and pathogen-inducible phytochemicals to plant innate immunity. Extensive studies on model plant species, particularly Arabidopsis thaliana, have brought significant advances in our understanding of the molecular mechanisms underpinning pathogen-triggered biosynthesis and activation of defensive secondary metabolites. However, despite the proven significance of secondary metabolites in plant response to pathogenic microorganisms, little is known about the precise mechanisms underlying their contribution to plant immunity. This insufficiency concerns information on the dynamics of cellular and subcellular localization of defensive phytochemicals during the encounters with microbial pathogens and precise knowledge on their mode of action. As many secondary metabolites are characterized by their in vitro antimicrobial activity, these compounds were commonly considered to function in plant defense as in planta antibiotics. Strikingly, recent experimental evidence suggests that at least some of these compounds alternatively may be involved in controlling several immune responses that are evolutionarily conserved in the plant kingdom, including callose deposition and programmed cell death.
Qualitative and quantitative composition of flavonoid and isoflavonoid glycosides as well as free... more Qualitative and quantitative composition of flavonoid and isoflavonoid glycosides as well as free aglycones in lupin seedlings (roots and aerial parts) grown under different light conditions or responding to infection with Pleiochaeta setosa, a fungus causing brown leaf spot, were monitored by liquid chromatography with UV and/or mass spectrometric detection. Both physical and biotic factors affected flavonoid and isoflavonoid levels in lupin tissues. Fungal infection evoked significant increase in the amounts of genistein, 2 -hydroxygenistein, and their prenylated derivatives that are thought to function as lupin phytoalexins. Effect on quantitative changes of glycosylated flavonoids and isoflavonoids in the roots and aerial parts was less significant. Moreover, different light conditions applied during seedling growth caused relative changes of flavonoid and isoflavonoid conjugates composition, especially in the leaves of white lupin plants. The chemical structures of flavonoid and isoflavonoid conjugates present in Lupinus angustifolius were elucidated. In addition to genistein and 2 -hydroxygenistein glycosides, flavonol conjugates were identified in leaves,
A total of eleven alkali-released, aromatic compounds were identified by HPLC, MS and NMR analyse... more A total of eleven alkali-released, aromatic compounds were identified by HPLC, MS and NMR analyses in cell wall extracts from Arabidopsis thaliana roots. Nine of them together constituted the three complete series of 4-hydroxy-, 4-hydroxy-3-methoxy, and 4hydroxy-3,5-dimethoxy-substituted benzaldehydes, benzoic acids and cinnamic acids. The other two were indolic metabolites: indole-3-carboxylic acid and indole-3-carbaldehyde. Qualitatively similar, but quantitatively distinct profiles were obtained using cell-wall extracts from A. thaliana leaves. Several of these compounds, particularly indole-3-carboxylic acid, 4-hydroxybenzoic acid and all four aldehydes, increased considerably in concentration upon infection of roots with Pythium sylvaticum, as did at least some of them upon infection of leaves with Pseudomonas syringae pv tomato. Comparison of these results with analogous data on a variety of different plant species suggests a remarkable structural uniformity among the majority of constitutive as well as infectioninduced, aromatic cell wall-bound compounds throughout the entire plant kingdom-in sharp contrast to the highly speciesspecific, chemically highly divers bouquets of soluble aromatic metabolites. #
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