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Ian E. Woodrow - One of the best experts on this subject based on the ideXlab platform.
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Ontogenetic and temporal trajectories of chemical defence in a cyanogenic eucalypt
Oecologia, 2007Co-Authors: Jason Q. D. Goodger, Thereis Y. S. Choo, Ian E. WoodrowAbstract:Many studies have shown that similarly aged plants within a species or population can vary markedly in the concentration of defence compounds they deploy to protect themselves from herbivores. Some studies have also shown that the concentration of these compounds can change with development, but no empirical research has mapped such an ontogenetic trajectory in detail. To do this, we grew cyanogenic Eucalyptus yarraensis seedlings from three half-sibling families under constant glasshouse conditions, and followed their foliar cyanogenic glycoside (Prunasin) concentration over time for 338 days after sowing (DAS). Plants in all families followed a similar temporal pattern. Plants increased in foliar Prunasin concentration from a very low level (10 μg cyanide (CN) equivalents g^−1) in their first leaves, to a maximum of, on average, 1.2 mg CN g^−1 at about 240 DAS. From 240 to 338 DAS, Prunasin concentration gradually decreased to around 0.7 mg CN g^−1. Significant differences between families in maximum Prunasin concentration were detected, but none were detected in the time at which this maximum occurred. In parallel with these changes in Prunasin concentration, we detected an approximately linear increase in leaf mass per unit leaf area (LMA) with time, which reflected a change from juvenile to adult-like leaf anatomy. When ontogenetic trajectories of Prunasin against LMA were constructed, we failed to detect a significant difference between families in the LMA at which maximum Prunasin concentration occurred. This remarkable similarity in the temporal and ontogenetic trajectories between individuals, even from geographically remote families, is discussed in relation to a theoretical model for ontogenetic changes in plant defence. Our results show that ontogeny can constrain the expression of plant chemical defense and that chemical defense changes in a nonlinear fashion with ontogeny.
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Cyanogenic glycosides from the rare Australian endemic rainforest tree Clerodendrum grayi (Lamiaceae).
Phytochemistry, 2005Co-Authors: Rebecca E. Miller, Malcolm J. Mcconville, Ian E. WoodrowAbstract:Abstract The cyanogenic diglycoside lucumin (( R )-mandelonitrile-β- d -primeveroside) and monoglucoside Prunasin (( R )-mandelonitrile-β- d -glucoside) were isolated from the foliage of the rare Australian rainforest tree species Clerodendrum grayi (Lamiaceae). This is the first reported isolation of the diglycoside lucumin from vegetative tissue (foliage), and the first reported co-occurrence of lucumin and Prunasin. Furthermore, unusually, the diglycoside lucumin was the most abundant cyanogen accounting for approximately 60% of total cyanide in a leaf tissue.
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Cyanogenic Eucalyptus nobilis is polymorphic for both Prunasin and specific β-glucosidases
Phytochemistry, 2003Co-Authors: Roslyn M. Gleadow, A. C. Vecchies, Ian E. WoodrowAbstract:Abstract Cyanogenesis (i.e. the evolution of HCN from damaged plant tissue) requires the presence of two biochemical pathways, one controlling synthesis of the cyanogenic glycoside and the other controlling the production of a specific degradative β-glucosidase. The sole cyanogenic glycoside in Eucalyptus nobilis was identified as Prunasin ( d -mandelonitrile β- d -glucoside) using HPLC and GC–MS. Seedlings from three populations of E. nobilis were grown under controlled conditions and 38% were found to be acyanogenic, a proportion far greater than reported for any other cyanogenic eucalypt. A detailed study of the acyanogenic progeny from a single open-pollinated parent found that 23% lacked a cyanogenic β-glucosidase, 32% lacked Prunasin and 9% lacked both. Of the remaining seedlings initially identified as acyanogenics, 27% contained either trace amounts of β-glucosidase or Prunasin, while 9% contained trace amounts of both. Results support the hypothesis that the two components necessary for cyanogenesis are inherited independently. Trace amounts are likely to result from the presence of non-specific β-glucosidases or the glycosylation of the cyanohydrin intermediate by non-specific UDP glycosyl transferases.
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Light alters the allocation of nitrogen to cyanogenic glycosides in Eucalyptus cladocalyx
Oecologia, 2002Co-Authors: Anna E. Burns, Roslyn M. Gleadow, Ian E. WoodrowAbstract:The effect of light on the partitioning of resources between photosynthesis and chemical defence was studied in Eucalyptus cladocalyx F. Muell. This species allocates up to 15% of leaf nitrogen to the constitutive cyanogenic glycoside, Prunasin, making it an ideal system for studying resource allocation. By controlling the level of leaf nitrogen we were able to test the hypothesis that light limitation would result in the effective reallocation of nitrogen from the defensive to the photosynthetic apparatus. Seedlings were grown in full light or shade and supplied with 1.5 mM or 6 mM nitrogen in a 2×2 factorial design. We found that shading effected a decrease in the concentration of the cyanogenic glycoside, Prunasin, and little if any change in the concentration of carbon-based secondary metabolites (total phenolics and condensed tannins). There was also significantly less Prunasin, relative to total leaf nitrogen, chlorophyll concentration and carbon assimilation rates, when grown plants were grown in shade, particularly when there was an ample supply of nitrogen. This pattern is likely to be the result of relative changes in the energetic and resource costs of photosynthesis and defensive compounds at different photon flux densities.
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Cyanogenic polymorphism in Eucalyptus polyanthemos Schauer subsp vestita L. Johnson and K. Hill (Myrtaceae)
Biochemical Systematics and Ecology, 2002Co-Authors: Jason Q. D. Goodger, Robert J. Capon, Ian E. WoodrowAbstract:Plant cyanogenesis, the release of cyanide from endogenous cyanide-containing compounds, is an effective herbivore deterrent. This paper characterises cyanogenesis in the Australian tree Eucalyptus polyanthemos Schauer subsp. vestita L. Johnson and K. Hill for the first time. The cyanogenic glucoside Prunasin ((R)-mandelonitrile beta-D-glucoside) was determined to be the only cyanogenic compound in E. polyanthemos foliage. Two natural populations of E. polyanthernos showed quantitative variation in foliar prumasin concentration, varying from zero (i.e. acyanogenic) to 2.07 mg CN g(-1) dry weight in one population and from 0.17 to 1.98 mg CN g(-1) dry weight in the other. No significant difference was detected between the populations with respect to the mean Prunasin concentration or the degree of variation in foliar Prunasin, despite significant differences in foliar nitrogen. Variation between individuals was also observed with respect to the capacity of foliage to catabolise Prunasin to form cyanide. Moreover, variation in this capacity generally correlated with the amount of Prunasin in the tissue, suggesting genetic linkage between Prunasin and beta-glucosidase. (C) 2002 Elsevier Science Ltd. All rights reserved.
Jonathan E. Poulton - One of the best experts on this subject based on the ideXlab platform.
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Immunocytochemical Localization of Prunasin Hydrolase and Mandelonitrile Lyase in Stems and Leaves of Prunus serotina.
Plant physiology, 1994Co-Authors: Elisabeth Swain, Jonathan E. PoultonAbstract:In macerates of black cherry (Prunus serotina Ehrh.) leaves and stems, (R)-Prunasin is catabolized to HCN, benzaldehyde, and D-glucose by the sequential action of Prunasin hydrolase (EC 3.2.1.21) and (R)-(+)-mandelonitrile lyase (EC 4.1.2.10). Immuno-cytochemical techniques have shown that within these organs Prunasin hydrolase occurs within the vacuoles of phloem parenchyma cells. In arborescent leaves, mandelonitrile lyase was also located in phloem parenchyma vacuoles, but comparison of serial sections revealed that these two degradative enzymes are usually localized within different cells.
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Tissue and Subcellular Localization of Enzymes Catabolizing (R)-Amygdalin in Mature Prunus serotina Seeds
Plant physiology, 1992Co-Authors: Elisabeth Swain, Jonathan E. PoultonAbstract:In black cherry (Prunus serotina Ehrh.) homogenates, (R)-amygdalin is catabolized to HCN, benzaldehyde, and d-glucose by the sequential action of amygdalin hydrolase, Prunasin hydrolase, and mandelonitrile lyase. The tissue and subcellular localizations of these enzymes were determined within intact black cherry seeds by direct enzyme analysis, immunoblotting, and colloidal gold immunocytochemical techniques. Taken together, these procedures showed that the two β-glucosidases are restricted to protein bodies of the procambium, which ramifies throughout the cotyledons. Although amygdalin hydrolase occurred within the majority of procambial cells, Prunasin hydrolase was confined to the peripheral layers of this meristematic tissue. Highest levels of mandelonitrile lyase were observed in the protein bodies of the cotyledonary parenchyma cells, with lesser amounts in the procambial cell protein bodies. The residual endosperm tissue had insignificant levels of amygdalin hydrolase, Prunasin hydrolase, and mandelonitrile lyase.
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development of the potential for cyanogenesis in maturing black cherry prunus serotina ehrh fruits
Plant Physiology, 1992Co-Authors: Elisabeth Swain, Chun Ping Li, Jonathan E. PoultonAbstract:Biochemical changes related to cyanogenesis (hydrogen cyanide production) were monitored during maturation of black cherry (Prunus serotina Ehrh.) fruits. At weekly intervals from flowering until maturity, fruits (or selected parts thereof) were analyzed for (a) fresh and dry weights, (b) Prunasin and amygdalin levels, and (c) levels of the catabolic enzymes amygdalin hydrolase, Prunasin hydrolase, and mandelonitrile lyase. During phase I (0-28 days after flowering [DAF]), immature fruits accumulated Prunasin (mean: 3 micromoles/fruit) but were acyanogenic because they lacked the above enzymes. Concomitant with cotyledon development during mid-phase II, the seeds began accumulating both amygdalin (mean: 3 micromoles/seed) and the catabolic enzymes and were highly cyanogenic upon tissue disruption. Meanwhile, Prunasin levels rapidly declined and were negligible by maturity. During phases II (29-65 DAF) and III (66-81 DAF), the pericarp also accumulated amygdalin, whereas its Prunasin content declined toward maturity. Lacking the catabolic enzymes, the pericarp remained acyanogenic throughout all developmental stages.
Elisabeth Swain - One of the best experts on this subject based on the ideXlab platform.
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Immunocytochemical Localization of Prunasin Hydrolase and Mandelonitrile Lyase in Stems and Leaves of Prunus serotina.
Plant physiology, 1994Co-Authors: Elisabeth Swain, Jonathan E. PoultonAbstract:In macerates of black cherry (Prunus serotina Ehrh.) leaves and stems, (R)-Prunasin is catabolized to HCN, benzaldehyde, and D-glucose by the sequential action of Prunasin hydrolase (EC 3.2.1.21) and (R)-(+)-mandelonitrile lyase (EC 4.1.2.10). Immuno-cytochemical techniques have shown that within these organs Prunasin hydrolase occurs within the vacuoles of phloem parenchyma cells. In arborescent leaves, mandelonitrile lyase was also located in phloem parenchyma vacuoles, but comparison of serial sections revealed that these two degradative enzymes are usually localized within different cells.
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Utilization of Amygdalin during Seedling Development of Prunus serotina
Plant physiology, 1994Co-Authors: Elisabeth Swain, J. E. PoultonAbstract:Cotyledons of mature black cherry (Prunus serotina Ehrh.) seeds contain the cyanogenic diglucoside (R)-amygdalin. The levels of amygdalin, its corresponding monoglucoside (R)-Prunasin, and the enzymes that metabolize these cyanoglycosides were measured during the course of seedling development. During the first 3 weeks following imbibition, cotyledonary amygdalin levels declined by more than 80%, but free hydrogen cyanide was not released to the atmosphere. Concomitantly, Prunasin, which was not present in mature, ungerminated seeds, accumulated in the seedling epicotyls, hypocotyls, and cotyledons to levels approaching 4 [mu]mol per seedling. Whether this Prunasin resulted from amygdalin hydrolysis remains unclear, however, because these organs also possess UDPG:mandelonitrile glucosyltransferase, which catalyzes de novo Prunasin biosynthesis. The reduction in amygdalin levels was paralleled by declines in the levels of amygdalin hydrolase (AH), Prunasin hydrolase (PH), mandelonitrile lyase (MDL), and [beta]-cyanoalanine synthase. At all stages of seedling development, AH and PH were localized by immunocytochemistry within the vascular tissues. In contrast, MDL occurred mostly in the cotyledonary parenchyma cells but was also present in the vascular tissues. Soon after imbibition, AH, PH, and MDL were found within protein bodies but were later detected in vacuoles derived from these organelles.
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Tissue and Subcellular Localization of Enzymes Catabolizing (R)-Amygdalin in Mature Prunus serotina Seeds
Plant physiology, 1992Co-Authors: Elisabeth Swain, Jonathan E. PoultonAbstract:In black cherry (Prunus serotina Ehrh.) homogenates, (R)-amygdalin is catabolized to HCN, benzaldehyde, and d-glucose by the sequential action of amygdalin hydrolase, Prunasin hydrolase, and mandelonitrile lyase. The tissue and subcellular localizations of these enzymes were determined within intact black cherry seeds by direct enzyme analysis, immunoblotting, and colloidal gold immunocytochemical techniques. Taken together, these procedures showed that the two β-glucosidases are restricted to protein bodies of the procambium, which ramifies throughout the cotyledons. Although amygdalin hydrolase occurred within the majority of procambial cells, Prunasin hydrolase was confined to the peripheral layers of this meristematic tissue. Highest levels of mandelonitrile lyase were observed in the protein bodies of the cotyledonary parenchyma cells, with lesser amounts in the procambial cell protein bodies. The residual endosperm tissue had insignificant levels of amygdalin hydrolase, Prunasin hydrolase, and mandelonitrile lyase.
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development of the potential for cyanogenesis in maturing black cherry prunus serotina ehrh fruits
Plant Physiology, 1992Co-Authors: Elisabeth Swain, Chun Ping Li, Jonathan E. PoultonAbstract:Biochemical changes related to cyanogenesis (hydrogen cyanide production) were monitored during maturation of black cherry (Prunus serotina Ehrh.) fruits. At weekly intervals from flowering until maturity, fruits (or selected parts thereof) were analyzed for (a) fresh and dry weights, (b) Prunasin and amygdalin levels, and (c) levels of the catabolic enzymes amygdalin hydrolase, Prunasin hydrolase, and mandelonitrile lyase. During phase I (0-28 days after flowering [DAF]), immature fruits accumulated Prunasin (mean: 3 micromoles/fruit) but were acyanogenic because they lacked the above enzymes. Concomitant with cotyledon development during mid-phase II, the seeds began accumulating both amygdalin (mean: 3 micromoles/seed) and the catabolic enzymes and were highly cyanogenic upon tissue disruption. Meanwhile, Prunasin levels rapidly declined and were negligible by maturity. During phases II (29-65 DAF) and III (66-81 DAF), the pericarp also accumulated amygdalin, whereas its Prunasin content declined toward maturity. Lacking the catabolic enzymes, the pericarp remained acyanogenic throughout all developmental stages.
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Development ofthePotential forCyanogenesis inMaturing BlackCherry (Prunus serotina Ehrh.) Fruits1
1992Co-Authors: Elisabeth SwainAbstract:Biochemical changes related tocyanogenesis (hydrogen cyanideproduction) weremonitored during maturation ofblack cherry (Prunus serotina Ehrh.) fruits. Atweekly intervals from flowering until maturity, fruits (orselected partsthereof) were analyzed for(a)fresh anddryweights, (b)Prunasin andamygdalin levels, and(c)levels ofthecatabolic enzymesamygdalin hydrolase, Prunasin hydrolase, andmandelonitrile lyase. During phase1(0-28 daysafter flowering [DAF]), immature fruits accumulated Prunasin (mean: 3micromoles/fruit) butwereacyanogenic because they lacked theabove enzymes. Concomitant with cotyledon development during mid-phase 11, theseedsbegan accumulating bothamygdalin (mean: 3micromoles/seed) andthe catabolic enzymesandwerehighly cyanogenic upontissue disruption. Meanwhile, Prunasin levels rapidly declined andwere negligible bymaturity. During phases 11(29-65 DAF)andIII (6681DAF), thepericarp alsoaccumulated amygdalin, whereas its Prunasin content declined toward maturity. Lacking thecatabolic enzymes, thepericarp remained acyanogenic throughout all developmental stages.
Raquel Sánchez-pérez - One of the best experts on this subject based on the ideXlab platform.
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β-Glucosidase activity in almond seeds
Plant physiology and biochemistry : PPB, 2017Co-Authors: Jorge Del Cueto, Federico Dicenta, Birger L Møller, Raquel Sánchez-pérezAbstract:Abstract Almond bitterness is the most important trait for breeding programs since bitter-kernelled seedlings are usually discarded. Amygdalin and its precursor Prunasin are hydrolyzed by specific enzymes called β-glucosidases. In order to better understand the genetic control of almond bitterness, some studies have shown differences in the location of Prunasin hydrolases (PH, the β-glucosidase that degrades Prunasin) in sweet and bitter genotypes. The aim of this work was to isolate and characterize different PHs in sweet- and bitter-kernelled almonds to determine whether differences in their genomic or protein sequences are responsible for the sweet or bitter taste of their seeds. RNA was extracted from the tegument, nucellus and cotyledon of one sweet (Lauranne) and two bitter (D05–187 and S3067) almond genotypes throughout fruit ripening. Sequences of nine positive Phs were then obtained from all of the genotypes by RT-PCR and cloning. These clones, from mid ripening stage, were expressed in a heterologous system in tobacco plants by agroinfiltration. The PH activity was detected using the Feigl-Anger method and quantifying the hydrogen cyanide released with Prunasin as substrate. Furthermore, β-glucosidase activity was detected by Fast Blue BB salt and Umbelliferyl method. Differences at the sequence level (SNPs) and in the activity assays were detected, although no correlation with bitterness was found.
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Cyanogenic Glucosides and Derivatives in Almond and Sweet Cherry Flower Buds from Dormancy to Flowering.
Frontiers in plant science, 2017Co-Authors: Jorge Del Cueto, Irina A Ionescu, Martina Pičmanová, Oliver Gericke, Mohammed S Motawia, Carl E Olsen, José Antonio Campoy, Federico Dicenta, Birger L Møller, Raquel Sánchez-pérezAbstract:Almond and sweet cherry are two economically important species of the Prunus genus. They both produce the cyanogenic glucosides Prunasin and amygdalin. As part of a two-component defense system, Prunasin and amygdalin release toxic hydrogen cyanide upon cell disruption. In this study, we investigated the potential role of Prunasin and amygdalin and some of its derivatives in endodormancy release of these two Prunus species. The content of Prunasin and of endogenous Prunasin turnover products in the course of flower development/opening was examined in five almond cultivars – differing from very early to extra-late in flowering time – and in one sweet early cherry cultivar. In all cultivars, Prunasin began to accumulate in the flower buds shortly after dormancy release and the levels dropped again just before flowering time. In almond and sweet cherry, the turnover of Prunasin coincided with increased levels of Prunasin amide whereas Prunasin anitrile pentoside and beta-D-glucose-1-benzoate were abundant in almond and cherry flower buds at certain developmental stages. These findings indicate a role for the turnover of cyanogenic glucosides in controlling flower development/opening in Prunus species.
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Cyanogenic Glucosides and Derivatives in Almond and Sweet Cherry Flower Buds from Dormancy to Flowering.
Frontiers in Plant Science, 2017Co-Authors: Jorge Del Cueto, Irina A Ionescu, Martina Pičmanová, Oliver Gericke, Mohammed S Motawia, Carl E Olsen, José Antonio Campoy, Federico Dicenta, Birger L Møller, Raquel Sánchez-pérezAbstract:Almond and sweet cherry are two economically important species of the Prunus genus. They both produce the cyanogenic glucosides Prunasin and amygdalin. As part of a two-component defense system, Prunasin and amygdalin release toxic hydrogen cyanide upon cell disruption. In this study, we investigated the potential role within Prunasin and amygdalin and some of its derivatives in endodormancy release of these two Prunus species. The content of Prunasin and of endogenous Prunasin turnover products in the course of flower development was examined in five almond cultivars - differing from very early to extra-late in flowering time - and in one sweet early cherry cultivar. In all cultivars, Prunasin began to accumulate in the flower buds shortly after dormancy release and the levels dropped again just before flowering time. In almond and sweet cherry, the turnover of Prunasin coincided with increased levels of Prunasin amide whereas Prunasin anitrile pentoside and β-D-glucose-1-benzoate were abundant in almond and cherry flower buds at certain developmental stages. These findings indicate a role for the turnover of cyanogenic glucosides in controlling flower development in Prunus species.
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Prunasin Hydrolases during Fruit Development in Sweet and Bitter Almonds
Plant physiology, 2012Co-Authors: Raquel Sánchez-pérez, Federico Dicenta, Birger L Møller, Fara Sáez Belmonte, Jonas Borch, Kirsten JørgensenAbstract:Amygdalin is a cyanogenic diglucoside and constitutes the bitter component in bitter almond (Prunus dulcis). Amygdalin concentration increases in the course of fruit formation. The monoglucoside Prunasin is the precursor of amygdalin. Prunasin may be degraded to hydrogen cyanide, glucose, and benzaldehyde by the action of the β-glucosidase Prunasin hydrolase (PH) and mandelonitirile lyase or be glucosylated to form amygdalin. The tissue and cellular localization of PHs was determined during fruit development in two sweet and two bitter almond cultivars using a specific antibody toward PHs. Confocal studies on sections of tegument, nucellus, endosperm, and embryo showed that the localization of the PH proteins is dependent on the stage of fruit development, shifting between apoplast and symplast in opposite patterns in sweet and bitter cultivars. Two different PH genes, Ph691 and Ph692, have been identified in a sweet and a bitter almond cultivar. Both cDNAs are 86% identical on the nucleotide level, and their encoded proteins are 79% identical to each other. In addition, Ph691 and Ph692 display 92% and 86% nucleotide identity to Ph1 from black cherry (Prunus serotina). Both proteins were predicted to contain an amino-terminal signal peptide, with the size of 26 amino acid residues for PH691 and 22 residues for PH692. The PH activity and the localization of the respective proteins in vivo differ between cultivars. This implies that there might be different concentrations of Prunasin available in the seed for amygdalin synthesis and that these differences may determine whether the mature almond develops into bitter or sweet.
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Bitterness in almonds.
Plant physiology, 2008Co-Authors: Raquel Sánchez-pérez, Carl E Olsen, Federico Dicenta, Kirsten Jørgensen, Birger L MøllerAbstract:Bitterness in almond (Prunus dulcis) is determined by the content of the cyanogenic diglucoside amygdalin. The ability to synthesize and degrade Prunasin and amygdalin in the almond kernel was studied throughout the growth season using four different genotypes for bitterness. Liquid chromatography-mass spectrometry analyses showed a specific developmentally dependent accumulation of Prunasin in the tegument of the bitter genotype. The Prunasin level decreased concomitant with the initiation of amygdalin accumulation in the cotyledons of the bitter genotype. By administration of radiolabeled phenylalanine, the tegument was identified as a specific site of synthesis of Prunasin in all four genotypes. A major difference between sweet and bitter genotypes was observed upon staining of thin sections of teguments and cotyledons for β-glucosidase activity using Fast Blue BB salt. In the sweet genotype, the inner epidermis in the tegument facing the nucellus was rich in cytoplasmic and vacuolar localized β-glucosidase activity, whereas in the bitter cultivar, the β-glucosidase activity in this cell layer was low. These combined data show that in the bitter genotype, Prunasin synthesized in the tegument is transported into the cotyledon via the transfer cells and converted into amygdalin in the developing almond seed, whereas in the sweet genotype, amygdalin formation is prevented because the Prunasin is degraded upon passage of the β-glucosidase-rich cell layer in the inner epidermis of the tegument. The Prunasin turnover may offer a buffer supply of ammonia, aspartic acid, and asparagine enabling the plants to balance the supply of nitrogen to the developing cotyledons.
Jason Q. D. Goodger - One of the best experts on this subject based on the ideXlab platform.
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Ontogenetic and temporal trajectories of chemical defence in a cyanogenic eucalypt
Oecologia, 2007Co-Authors: Jason Q. D. Goodger, Thereis Y. S. Choo, Ian E. WoodrowAbstract:Many studies have shown that similarly aged plants within a species or population can vary markedly in the concentration of defence compounds they deploy to protect themselves from herbivores. Some studies have also shown that the concentration of these compounds can change with development, but no empirical research has mapped such an ontogenetic trajectory in detail. To do this, we grew cyanogenic Eucalyptus yarraensis seedlings from three half-sibling families under constant glasshouse conditions, and followed their foliar cyanogenic glycoside (Prunasin) concentration over time for 338 days after sowing (DAS). Plants in all families followed a similar temporal pattern. Plants increased in foliar Prunasin concentration from a very low level (10 μg cyanide (CN) equivalents g^−1) in their first leaves, to a maximum of, on average, 1.2 mg CN g^−1 at about 240 DAS. From 240 to 338 DAS, Prunasin concentration gradually decreased to around 0.7 mg CN g^−1. Significant differences between families in maximum Prunasin concentration were detected, but none were detected in the time at which this maximum occurred. In parallel with these changes in Prunasin concentration, we detected an approximately linear increase in leaf mass per unit leaf area (LMA) with time, which reflected a change from juvenile to adult-like leaf anatomy. When ontogenetic trajectories of Prunasin against LMA were constructed, we failed to detect a significant difference between families in the LMA at which maximum Prunasin concentration occurred. This remarkable similarity in the temporal and ontogenetic trajectories between individuals, even from geographically remote families, is discussed in relation to a theoretical model for ontogenetic changes in plant defence. Our results show that ontogeny can constrain the expression of plant chemical defense and that chemical defense changes in a nonlinear fashion with ontogeny.
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Cyanogenic polymorphism in Eucalyptus polyanthemos Schauer subsp vestita L. Johnson and K. Hill (Myrtaceae)
Biochemical Systematics and Ecology, 2002Co-Authors: Jason Q. D. Goodger, Robert J. Capon, Ian E. WoodrowAbstract:Plant cyanogenesis, the release of cyanide from endogenous cyanide-containing compounds, is an effective herbivore deterrent. This paper characterises cyanogenesis in the Australian tree Eucalyptus polyanthemos Schauer subsp. vestita L. Johnson and K. Hill for the first time. The cyanogenic glucoside Prunasin ((R)-mandelonitrile beta-D-glucoside) was determined to be the only cyanogenic compound in E. polyanthemos foliage. Two natural populations of E. polyanthernos showed quantitative variation in foliar prumasin concentration, varying from zero (i.e. acyanogenic) to 2.07 mg CN g(-1) dry weight in one population and from 0.17 to 1.98 mg CN g(-1) dry weight in the other. No significant difference was detected between the populations with respect to the mean Prunasin concentration or the degree of variation in foliar Prunasin, despite significant differences in foliar nitrogen. Variation between individuals was also observed with respect to the capacity of foliage to catabolise Prunasin to form cyanide. Moreover, variation in this capacity generally correlated with the amount of Prunasin in the tissue, suggesting genetic linkage between Prunasin and beta-glucosidase. (C) 2002 Elsevier Science Ltd. All rights reserved.
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Cyanogenic polymorphism as an indicator of genetic diversity in the rare species Eucalyptus yarraensis (Myrtaceae).
Functional plant biology : FPB, 2002Co-Authors: Jason Q. D. Goodger, Ian E. WoodrowAbstract:The rare Australian tree Eucalyptus yarraensis Maiden & Cambage is cyanogenic, a quantitative trait potentially indicative of genetic diversity. Cyanogenic plants are capable of releasing cyanide from endogenous cyanide-containing compounds. Cyanide is toxic or deterrent to generalist or non-adapted specialist herbivores. Consequently, cyanogenic plants are afforded an effective means of chemical defense. In this paper we characterize quantitative variation in cyanogenic capability, known as cyanogenic polymorphism, in E. yarraensis for the first time. We show that the cyanogenic glucoside Prunasin (R-mandelonitrile-β-D-glucoside) is the only cyanogenic compound in E. yarraensis foliage. We also show that two natural populations of E. yarraensis display extensive intra- and inter-population variation in foliar Prunasin concentration. The high Prunasin concentrations reported in this paper represent the highest yet recorded for mature eucalypt leaves. The cyanogenic variation could not be attributed to measured physical and chemical parameters, supporting the hypothesis that the variation is genetically based. A preliminary progeny trial also supports this hypothesis, with narrow sense heritability estimated at 1.17 from three half-sibling families. The variation in cyanogenic capability may be a useful tool in the development of a conservation strategy for the species.
