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Erik Christiansen - One of the best experts on this subject based on the ideXlab platform.
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induction of anatomically based defense responses in stems of diverse conifers by methyl jasmonate a phylogenetic perspective
Tree Physiology, 2004Co-Authors: J W Hudgins, Erik Christiansen, Vincent R. FranceschiAbstract:Conifers have evolved constitutive and inducible defense mechanisms to help in both wound healing and defense against attack by bark beetles and other organisms. These defenses include oleoresin, phenolics, and static structures in secondary phloem, such as lignified Cells and calcium oxalate crystals, that create physical barriers. We used a phylogenetic aPProach to investigate the defense anatomy of conifer stems of 13 species from five families following treatment with methyl jasmonate (MJ), a compound that induces defense responses in stems of several Pinaceae species. Methyl jasmonate induced a response similar to wounding except that the response was not accompanied by lesion formation, necrosis or a hypersensitive response. In the Pinaceae species studied, MJ induced polyphenolic parenchyma (PP) Cell activation and xylem traumatic resin duct (TD) formation. Members of the Taxodiaceae, which are not known to produce large quantities of resin, showed massive xylem TD formation and surface resinosis following MJ treatment. Treatment with MJ caused members of the Araucariaceae and Cupressaceae to form axial phloem resin ducts but not xylem ducts, whereas Podocarpaceae species showed no induction of resin-producing structures. All species treated with MJ showed phenolic deposition in PP Cells, and early lignification of phloem fibers was observed in most of the non-Pinaceae species. We conclude that, although evolution of resin-producing structures occurred independently in conifer lineages, MJ seems to induce resin production regardless of tissue location, as well as inducing deposition of phenolic compounds. Co-evolution of conifer defensive strategies and bark beetle pests is discussed.
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phloem parenchyma Cells are involved in local and distant defense responses to fungal inoculation or bark beetle attack in norway spruce pinaceae
American Journal of Botany, 2000Co-Authors: Vincent R. Franceschi, Paal Krokene, Trygve Krekling, Erik ChristiansenAbstract:The anatomical response of Norway spruce bark polyphenolic parenchyma Cells (PP Cells) to inoculation with the phytopathogenic fungus Ceratocystis polonica and attack by its bark-beetle vector Ips typographus was examined. Fungal inoculation on the periderm surface had no effect, while inoculation just below the periderm or halfway into the phloem (mid-phloem) generated detectable responses within 3 wk. The responses included increase in PP Cell size and in periodic acid-Schiff’s staining of PP Cell phenolics, wound periderm initiation from PP Cells, and cambial zone traumatic resin duct formation. Fungi were not seen in samples 3 wk after subperiderm or mid-phloem inoculation, but were found in some samples 6 and 9 wk after mid-phloem inoculation. In contrast, inoculations into the cambium resulted in partial (3 wk) or complete (6 and 9 wk) fungal colonization and death of tissue in the infected area. This indicates that PP Cells have defenses capable of inhibiting fungal growth. Samples taken near bark-beetle galleries had similar anatomical responses as inoculated samples, validating the inoculation aPProach to studying defense responses in spruce. These results show that PP Cells represent not only a constitutive defense system, but are also involved in local and remote inducible defenses against fungal and beetle attack.
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The structure and development of polyphenolic parenchyma Cells in Norway spruce (Picea abies) bark
Flora, 2000Co-Authors: Trygve Krekling, Vincent R. Franceschi, Alan A. Berryman, Erik ChristiansenAbstract:Summary A developmental and structural characterization of polyphenolic parenchyma Cells (PP Cells) in Norway spruce bark was undertaken as part of our studies on their role in defense against bark beetles and pathogenic fungi. PP Cells form multiple circumferentiallayers of Cells within the secondary phloem. A layer of PP Cells begins differentiation at the start of each growth season, delineating annual growth increments in the secondary phloem. The PP Cells grow in size over a number of years, and remain viable even in the oldest phloem layers of trees 100 years old. While most spruce clones examined had PP Cell layers that are one Cell thick, in one clone the PP Cell layer is 2 Cells thick with additional PP Cells scattered throughout the intervening blocks of sieve Cells. The additional Cells develop from undifferentiated axial parenchyma Cells during the first 5–8 years after formation of the PP Cell layer. Division of PP Cells in phloem layers older than 8 years give rise to additional PP Cells. This accommodates the expansion of the stem circumference while maintaining the intactness of this defense barrier. The importance of phenolic accumulation is also indicated by examination of early stem development. PP Cells are produced during the earliest stages of interfascicular cambium formation, and well organized layers are produced by the second year of growth. PP Cells in all layers of 25 year old tree bark contained starch, lipids and polyphenolics, which changed in amount or character in a seasonal pattern. Plasmodesmata are abundant between adjacent PP Cells and PP Cells and ray parenchyma, where they are probably important to nutrient and defense signal transport in the radial and axial directions. The formation of a new PP Cell layer each season, the maintenance of the Cells for many years, the early organization of this layer in the primary stem, and the dynamic physiological activity even older Cells exhibit, suPPorts previous work suggesting that PP Cells are an important protective tissue in the secondary phloem.
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specialized phloem parenchyma Cells in norway spruce pinaceae bark are an important site of defense reactions
American Journal of Botany, 1998Co-Authors: Vincent R. Franceschi, Trygve Krekling, Alan A. Berryman, Erik ChristiansenAbstract:The bark anatomy of Norway spruce clones that were resistant or susceptible to Ceratocystis polonica, a bark-beetle-vectored fungal pathogen, was compared. The major difference concerned the axial parenchyma Cells, called polyphenolic parenchyma (PP Cells) because of their vacuolar deposits. The phenolic nature of the deposits was indicated by autofluorescence under blue light, and immunocytochemical studies demonstrating PP Cells are enriched in phenylalanine ammonia lyase (EC 4.3.1.5), a key enzyme in phenolic synthesis. Susceptible-clone PP Cells occurred as single rows filled with dense deposits. The resistant clone had 40% more PP Cells, which occurred in rows two Cells thick plus as individual Cells scattered among the sieve Cells and had lighter deposits. Trees inoculated with fungus were analyzed but a distinct fungal response could not be separated from the general wound response. In the resistant clone, phenolic bodies were reduced in size and density or disaPPeared completely 12 d after wounding, and PP Cell size increased. The susceptible-clone phenolics and Cell size changed only slightly. These data show that PP Cells are active in synthesis, storage, and modification of phenolics in response to wounding, providing an important site of constitutive and inducible defenses.
Vincent R. Franceschi - One of the best experts on this subject based on the ideXlab platform.
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induction of anatomically based defense responses in stems of diverse conifers by methyl jasmonate a phylogenetic perspective
Tree Physiology, 2004Co-Authors: J W Hudgins, Erik Christiansen, Vincent R. FranceschiAbstract:Conifers have evolved constitutive and inducible defense mechanisms to help in both wound healing and defense against attack by bark beetles and other organisms. These defenses include oleoresin, phenolics, and static structures in secondary phloem, such as lignified Cells and calcium oxalate crystals, that create physical barriers. We used a phylogenetic aPProach to investigate the defense anatomy of conifer stems of 13 species from five families following treatment with methyl jasmonate (MJ), a compound that induces defense responses in stems of several Pinaceae species. Methyl jasmonate induced a response similar to wounding except that the response was not accompanied by lesion formation, necrosis or a hypersensitive response. In the Pinaceae species studied, MJ induced polyphenolic parenchyma (PP) Cell activation and xylem traumatic resin duct (TD) formation. Members of the Taxodiaceae, which are not known to produce large quantities of resin, showed massive xylem TD formation and surface resinosis following MJ treatment. Treatment with MJ caused members of the Araucariaceae and Cupressaceae to form axial phloem resin ducts but not xylem ducts, whereas Podocarpaceae species showed no induction of resin-producing structures. All species treated with MJ showed phenolic deposition in PP Cells, and early lignification of phloem fibers was observed in most of the non-Pinaceae species. We conclude that, although evolution of resin-producing structures occurred independently in conifer lineages, MJ seems to induce resin production regardless of tissue location, as well as inducing deposition of phenolic compounds. Co-evolution of conifer defensive strategies and bark beetle pests is discussed.
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Differential anatomical response of Norway spruce stem tissues to sterile and fungus infected inoculations
Trees, 2004Co-Authors: Trygve Krekling, Paal Krokene, Vincent R. Franceschi, Halvor SolheimAbstract:The anatomical defense responses in stems of Norway spruce ( Picea abies ) clones of different resistance to pathogenic fungi were characterized over time and distance from small mechanical wounds or wounds inoculated with the root rot fungus Heterobasidion annosum . Common responses for both treatments included division of ray parenchyma and other Cells in the cambial zone, accumulation of phenolic inclusions in ray parenchyma Cells, activation of phloem parenchyma (PP) Cells, and formation of traumatic resin ducts (TDs) in the xylem. TD formation occurred synchronously from a tangential layer of Cells, or symplasmic domain, within the zone of xylem mother Cells. TD induction is triggered by a signal, which propagates a developmental wave in the axial direction at about 2.5 cm per day. TDs are formed at least 30 cm above single inoculations within 16–36 days after inoculation. The size and number of TDs is attenuated further away from the inoculation site, indicating a dose-dependent activity leading to TD development. Compared to sterile wounding, fungal inoculation gave rise to more and larger TDs in all clones, and multiple rows of TDs in weak clones. Fungal inoculation also induced the formation of more new PP Cells, increasing the number of PP Cells in the phloem in the year of inoculation up to 100%. TD and PP Cell formation was greater in susceptible compared to resistant clones and after fungal versus sterile inoculation. Potential mechanisms responsible for this variable response are discussed.
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phloem parenchyma Cells are involved in local and distant defense responses to fungal inoculation or bark beetle attack in norway spruce pinaceae
American Journal of Botany, 2000Co-Authors: Vincent R. Franceschi, Paal Krokene, Trygve Krekling, Erik ChristiansenAbstract:The anatomical response of Norway spruce bark polyphenolic parenchyma Cells (PP Cells) to inoculation with the phytopathogenic fungus Ceratocystis polonica and attack by its bark-beetle vector Ips typographus was examined. Fungal inoculation on the periderm surface had no effect, while inoculation just below the periderm or halfway into the phloem (mid-phloem) generated detectable responses within 3 wk. The responses included increase in PP Cell size and in periodic acid-Schiff’s staining of PP Cell phenolics, wound periderm initiation from PP Cells, and cambial zone traumatic resin duct formation. Fungi were not seen in samples 3 wk after subperiderm or mid-phloem inoculation, but were found in some samples 6 and 9 wk after mid-phloem inoculation. In contrast, inoculations into the cambium resulted in partial (3 wk) or complete (6 and 9 wk) fungal colonization and death of tissue in the infected area. This indicates that PP Cells have defenses capable of inhibiting fungal growth. Samples taken near bark-beetle galleries had similar anatomical responses as inoculated samples, validating the inoculation aPProach to studying defense responses in spruce. These results show that PP Cells represent not only a constitutive defense system, but are also involved in local and remote inducible defenses against fungal and beetle attack.
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The structure and development of polyphenolic parenchyma Cells in Norway spruce (Picea abies) bark
Flora, 2000Co-Authors: Trygve Krekling, Vincent R. Franceschi, Alan A. Berryman, Erik ChristiansenAbstract:Summary A developmental and structural characterization of polyphenolic parenchyma Cells (PP Cells) in Norway spruce bark was undertaken as part of our studies on their role in defense against bark beetles and pathogenic fungi. PP Cells form multiple circumferentiallayers of Cells within the secondary phloem. A layer of PP Cells begins differentiation at the start of each growth season, delineating annual growth increments in the secondary phloem. The PP Cells grow in size over a number of years, and remain viable even in the oldest phloem layers of trees 100 years old. While most spruce clones examined had PP Cell layers that are one Cell thick, in one clone the PP Cell layer is 2 Cells thick with additional PP Cells scattered throughout the intervening blocks of sieve Cells. The additional Cells develop from undifferentiated axial parenchyma Cells during the first 5–8 years after formation of the PP Cell layer. Division of PP Cells in phloem layers older than 8 years give rise to additional PP Cells. This accommodates the expansion of the stem circumference while maintaining the intactness of this defense barrier. The importance of phenolic accumulation is also indicated by examination of early stem development. PP Cells are produced during the earliest stages of interfascicular cambium formation, and well organized layers are produced by the second year of growth. PP Cells in all layers of 25 year old tree bark contained starch, lipids and polyphenolics, which changed in amount or character in a seasonal pattern. Plasmodesmata are abundant between adjacent PP Cells and PP Cells and ray parenchyma, where they are probably important to nutrient and defense signal transport in the radial and axial directions. The formation of a new PP Cell layer each season, the maintenance of the Cells for many years, the early organization of this layer in the primary stem, and the dynamic physiological activity even older Cells exhibit, suPPorts previous work suggesting that PP Cells are an important protective tissue in the secondary phloem.
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specialized phloem parenchyma Cells in norway spruce pinaceae bark are an important site of defense reactions
American Journal of Botany, 1998Co-Authors: Vincent R. Franceschi, Trygve Krekling, Alan A. Berryman, Erik ChristiansenAbstract:The bark anatomy of Norway spruce clones that were resistant or susceptible to Ceratocystis polonica, a bark-beetle-vectored fungal pathogen, was compared. The major difference concerned the axial parenchyma Cells, called polyphenolic parenchyma (PP Cells) because of their vacuolar deposits. The phenolic nature of the deposits was indicated by autofluorescence under blue light, and immunocytochemical studies demonstrating PP Cells are enriched in phenylalanine ammonia lyase (EC 4.3.1.5), a key enzyme in phenolic synthesis. Susceptible-clone PP Cells occurred as single rows filled with dense deposits. The resistant clone had 40% more PP Cells, which occurred in rows two Cells thick plus as individual Cells scattered among the sieve Cells and had lighter deposits. Trees inoculated with fungus were analyzed but a distinct fungal response could not be separated from the general wound response. In the resistant clone, phenolic bodies were reduced in size and density or disaPPeared completely 12 d after wounding, and PP Cell size increased. The susceptible-clone phenolics and Cell size changed only slightly. These data show that PP Cells are active in synthesis, storage, and modification of phenolics in response to wounding, providing an important site of constitutive and inducible defenses.
Cesare Bordi - One of the best experts on this subject based on the ideXlab platform.
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Pancreatic polypeptide-related tumors
Peptides, 2002Co-Authors: Cesare Bordi, Cinzia Azzoni, Tiziana D'adda, Silvia PizziAbstract:PP-producing tumors are mostly located in the pancreas and may present as three pathologic lesions: pure PP-omas, mixed tumors with minor PP Cell population, and PP-Cell hyperplasia. These tumors are among the most common multiple adenomas frequently found in patients with multiple endocrine neoplasia type 1. Hypersecretion and high circulating levels of PP are frequently found. They are symptomless but may be useful for the identification of the pancreatic tumors. Numerous types of extrapancreatic endocrine tumors are able to synthesize and secrete PP. They occur mostly but not exclusively in the gastrointestinal tract, particularly in the rectum. The inactivation of the MEN 1 gene at 11q13 aPPears to be involved in the development of pancreatic but not of rectal PP-producing tumors.
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Pancreatic-polypeptide Cell hyperplasia associated with pancreatic or duodenal gastrinomas
Human pathology, 1997Co-Authors: Eugenia Marta Martella, Cinzia Azzoni, Gabriella Ferraro, Massimo Marignani, Cesare BordiAbstract:Abstract An immunohistochemical investigation of pancreatic-polypeptide (PP) Cells in the PP-rich region of the pancreas, of ventral embryological origin, was performed in three female patients affected by or previously operated on for functioning duodenal or pancreatic gastrinomas not associated with multiple endocrine neoplasia syndrome. A pronounced PP-Cell hyperplasia showing histological patterns of endocrine Cell dysplasia and focal adenomatosis as defined by Jaffe et al was found in all cases. Morphometric analysis showed that in these patients the fraction of ventral-type pancreatic lobules occupied by PP-immunoreactive Cells was 14.77 ± 5.73%, 8.94 ± 2.92%, and 10.83 ± 5.64%, respectively. These values were three to five times higher than the uPPer values found in controls (mean, 2.20%; range, 1.54 to 2.93%; P
Trygve Krekling - One of the best experts on this subject based on the ideXlab platform.
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Differential anatomical response of Norway spruce stem tissues to sterile and fungus infected inoculations
Trees, 2004Co-Authors: Trygve Krekling, Paal Krokene, Vincent R. Franceschi, Halvor SolheimAbstract:The anatomical defense responses in stems of Norway spruce ( Picea abies ) clones of different resistance to pathogenic fungi were characterized over time and distance from small mechanical wounds or wounds inoculated with the root rot fungus Heterobasidion annosum . Common responses for both treatments included division of ray parenchyma and other Cells in the cambial zone, accumulation of phenolic inclusions in ray parenchyma Cells, activation of phloem parenchyma (PP) Cells, and formation of traumatic resin ducts (TDs) in the xylem. TD formation occurred synchronously from a tangential layer of Cells, or symplasmic domain, within the zone of xylem mother Cells. TD induction is triggered by a signal, which propagates a developmental wave in the axial direction at about 2.5 cm per day. TDs are formed at least 30 cm above single inoculations within 16–36 days after inoculation. The size and number of TDs is attenuated further away from the inoculation site, indicating a dose-dependent activity leading to TD development. Compared to sterile wounding, fungal inoculation gave rise to more and larger TDs in all clones, and multiple rows of TDs in weak clones. Fungal inoculation also induced the formation of more new PP Cells, increasing the number of PP Cells in the phloem in the year of inoculation up to 100%. TD and PP Cell formation was greater in susceptible compared to resistant clones and after fungal versus sterile inoculation. Potential mechanisms responsible for this variable response are discussed.
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phloem parenchyma Cells are involved in local and distant defense responses to fungal inoculation or bark beetle attack in norway spruce pinaceae
American Journal of Botany, 2000Co-Authors: Vincent R. Franceschi, Paal Krokene, Trygve Krekling, Erik ChristiansenAbstract:The anatomical response of Norway spruce bark polyphenolic parenchyma Cells (PP Cells) to inoculation with the phytopathogenic fungus Ceratocystis polonica and attack by its bark-beetle vector Ips typographus was examined. Fungal inoculation on the periderm surface had no effect, while inoculation just below the periderm or halfway into the phloem (mid-phloem) generated detectable responses within 3 wk. The responses included increase in PP Cell size and in periodic acid-Schiff’s staining of PP Cell phenolics, wound periderm initiation from PP Cells, and cambial zone traumatic resin duct formation. Fungi were not seen in samples 3 wk after subperiderm or mid-phloem inoculation, but were found in some samples 6 and 9 wk after mid-phloem inoculation. In contrast, inoculations into the cambium resulted in partial (3 wk) or complete (6 and 9 wk) fungal colonization and death of tissue in the infected area. This indicates that PP Cells have defenses capable of inhibiting fungal growth. Samples taken near bark-beetle galleries had similar anatomical responses as inoculated samples, validating the inoculation aPProach to studying defense responses in spruce. These results show that PP Cells represent not only a constitutive defense system, but are also involved in local and remote inducible defenses against fungal and beetle attack.
-
The structure and development of polyphenolic parenchyma Cells in Norway spruce (Picea abies) bark
Flora, 2000Co-Authors: Trygve Krekling, Vincent R. Franceschi, Alan A. Berryman, Erik ChristiansenAbstract:Summary A developmental and structural characterization of polyphenolic parenchyma Cells (PP Cells) in Norway spruce bark was undertaken as part of our studies on their role in defense against bark beetles and pathogenic fungi. PP Cells form multiple circumferentiallayers of Cells within the secondary phloem. A layer of PP Cells begins differentiation at the start of each growth season, delineating annual growth increments in the secondary phloem. The PP Cells grow in size over a number of years, and remain viable even in the oldest phloem layers of trees 100 years old. While most spruce clones examined had PP Cell layers that are one Cell thick, in one clone the PP Cell layer is 2 Cells thick with additional PP Cells scattered throughout the intervening blocks of sieve Cells. The additional Cells develop from undifferentiated axial parenchyma Cells during the first 5–8 years after formation of the PP Cell layer. Division of PP Cells in phloem layers older than 8 years give rise to additional PP Cells. This accommodates the expansion of the stem circumference while maintaining the intactness of this defense barrier. The importance of phenolic accumulation is also indicated by examination of early stem development. PP Cells are produced during the earliest stages of interfascicular cambium formation, and well organized layers are produced by the second year of growth. PP Cells in all layers of 25 year old tree bark contained starch, lipids and polyphenolics, which changed in amount or character in a seasonal pattern. Plasmodesmata are abundant between adjacent PP Cells and PP Cells and ray parenchyma, where they are probably important to nutrient and defense signal transport in the radial and axial directions. The formation of a new PP Cell layer each season, the maintenance of the Cells for many years, the early organization of this layer in the primary stem, and the dynamic physiological activity even older Cells exhibit, suPPorts previous work suggesting that PP Cells are an important protective tissue in the secondary phloem.
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specialized phloem parenchyma Cells in norway spruce pinaceae bark are an important site of defense reactions
American Journal of Botany, 1998Co-Authors: Vincent R. Franceschi, Trygve Krekling, Alan A. Berryman, Erik ChristiansenAbstract:The bark anatomy of Norway spruce clones that were resistant or susceptible to Ceratocystis polonica, a bark-beetle-vectored fungal pathogen, was compared. The major difference concerned the axial parenchyma Cells, called polyphenolic parenchyma (PP Cells) because of their vacuolar deposits. The phenolic nature of the deposits was indicated by autofluorescence under blue light, and immunocytochemical studies demonstrating PP Cells are enriched in phenylalanine ammonia lyase (EC 4.3.1.5), a key enzyme in phenolic synthesis. Susceptible-clone PP Cells occurred as single rows filled with dense deposits. The resistant clone had 40% more PP Cells, which occurred in rows two Cells thick plus as individual Cells scattered among the sieve Cells and had lighter deposits. Trees inoculated with fungus were analyzed but a distinct fungal response could not be separated from the general wound response. In the resistant clone, phenolic bodies were reduced in size and density or disaPPeared completely 12 d after wounding, and PP Cell size increased. The susceptible-clone phenolics and Cell size changed only slightly. These data show that PP Cells are active in synthesis, storage, and modification of phenolics in response to wounding, providing an important site of constitutive and inducible defenses.
Cinzia Azzoni - One of the best experts on this subject based on the ideXlab platform.
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Pancreatic polypeptide-related tumors
Peptides, 2002Co-Authors: Cesare Bordi, Cinzia Azzoni, Tiziana D'adda, Silvia PizziAbstract:PP-producing tumors are mostly located in the pancreas and may present as three pathologic lesions: pure PP-omas, mixed tumors with minor PP Cell population, and PP-Cell hyperplasia. These tumors are among the most common multiple adenomas frequently found in patients with multiple endocrine neoplasia type 1. Hypersecretion and high circulating levels of PP are frequently found. They are symptomless but may be useful for the identification of the pancreatic tumors. Numerous types of extrapancreatic endocrine tumors are able to synthesize and secrete PP. They occur mostly but not exclusively in the gastrointestinal tract, particularly in the rectum. The inactivation of the MEN 1 gene at 11q13 aPPears to be involved in the development of pancreatic but not of rectal PP-producing tumors.
-
Pancreatic-polypeptide Cell hyperplasia associated with pancreatic or duodenal gastrinomas
Human pathology, 1997Co-Authors: Eugenia Marta Martella, Cinzia Azzoni, Gabriella Ferraro, Massimo Marignani, Cesare BordiAbstract:Abstract An immunohistochemical investigation of pancreatic-polypeptide (PP) Cells in the PP-rich region of the pancreas, of ventral embryological origin, was performed in three female patients affected by or previously operated on for functioning duodenal or pancreatic gastrinomas not associated with multiple endocrine neoplasia syndrome. A pronounced PP-Cell hyperplasia showing histological patterns of endocrine Cell dysplasia and focal adenomatosis as defined by Jaffe et al was found in all cases. Morphometric analysis showed that in these patients the fraction of ventral-type pancreatic lobules occupied by PP-immunoreactive Cells was 14.77 ± 5.73%, 8.94 ± 2.92%, and 10.83 ± 5.64%, respectively. These values were three to five times higher than the uPPer values found in controls (mean, 2.20%; range, 1.54 to 2.93%; P