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Ralph L. Nicholson - One of the best experts on this subject based on the ideXlab platform.

  • expression of a putative flavonoid 3 hydroxylase in sorghum Mesocotyls synthesizing 3 deoxyanthocyanidin phytoalexins
    Physiological and Molecular Plant Pathology, 2004
    Co-Authors: Jayanand Boddu, Ralph L. Nicholson, Catherine Svabek, Rajandeep S Sekhon, Amanda J Gevens, Daniel A Jones, Jeffery F Pedersen, David L Gustine, Surinder Chopra
    Abstract:

    Abstract In sorghum, ingress of Cochliobolus heterostrophus stimulates the synthesis of 3-deoxyanthocyanidins that act as phytoalexins. Apigeninidin and luteolinidin are two major phytoalexins induced in the first 24 h after infection. In an attempt to understand genetic regulation of the biosynthesis of sorghum phytoalexins, we isolated a differentially expressed partial cDNA. Characterization and comparison showed that this cDNA sequence corresponds to a putative flavonoid 3′-hydroxylase . Full length sequence characterization allowed us to establish that the sorghum putative f3′h cDNA encodes a peptide of 517 amino acids that has domains conserved among cytochrome P450 proteins functioning in the flavonoid biosynthetic pathway. Heterologous expression of the putative f3′h cDNA in Escherichia coli yielded a membrane preparation that catalyzed the hydroxylation of naringenin. We show here that transcription of the flavonoid 3′-hydroxylase was coordinately regulated with that of chalcone synthase and dihydroflavonol reductase, and expression of these genes was induced within the first 24 h of fungal challenge. Synthesis of apigeninidin and luteolinidin followed the induced expression of the f3′h gene, implicating its role in fungal induced expression of sorghum phytolaexins.

  • The effect of acibenzolar-S-methyl on phytoalexin and PR-protein induction on sorghum Mesocotyls and on Colletotrichum sublineolum
    Summa Phytopathologica, 2004
    Co-Authors: W. Osswald, José Renato Stangarlin, Ralph L. Nicholson, Maria Brummer, N. A. Wulff, Robson Marcelo Di Piero, E Piccinin, Luciana Di Ciero, F Hoto, Sérgio Florentino Pascholati
    Abstract:

    Treatment of sorghum Mesocotyls with the chemical activator benzo (1, 2, 3) thiadiazole-7-carbothioic acid S-methyl ester (BTH, acibenzolar-S-methyl) caused an induction of the phytoalexin apigeninidin. The induction became visible with 5 ppm BTH after an incubation time of 30 hours. The synthesis of three constitutively expressed β-1,3-glucanase isoforms was inhibited by BTH, but no significant effect of BTH was seen on the induction of a sorghum chitinase as demonstrated by immunoblotting experiments with specific antibodies. Besides these effects on sorghum Mesocotyls, BTH inhibited spore germination, germ tube and appressorium formation of the sorghum pathogen, Colletotrichum sublineolum. Spore germination and germ tube formation was significantly reduced with 5 ppm BTH, whereas inhibition of appressorium formation started with 10 ppm BTH. Finally, we demonstrated that mycelial growth of the pathogen was also reduced between 50 and 80% with 100 and 200 ppm BTH. Thus, BTH might act on the host pathogen interaction between sorghum and C. sublineolum as a fungitoxic compound and simultaneously as a resistance inducer.

  • cdna cloning of a sorghum pathogenesis related protein pr 10 and differential expression of defense related genes following inoculation with cochliobolus heterostrophus or colletotrichum sublineolum
    Molecular Plant-microbe Interactions, 1999
    Co-Authors: Szechung Clive Lo, John Hipskind, Ralph L. Nicholson
    Abstract:

    A sorghum cDNA clone was isolated by differential screening of a cDNA library prepared from Mesocotyls (cultivar DK18) inoculated with fungal pathogens. The deduced translation product shows sequence similarity to a family of intracellular pathogenesis-related proteins (PR-10) with a potential ribonuclease function. We studied the accumulation of PR-10 and chalcone synthase (CHS) transcripts in Mesocotyls following inoculation with Cochliobolus heterostrophus or Colletotrichum sublineolum. CHS is involved in phytoalexin synthesis in sorghum. Coordinate expression of PR-10 and CHS genes was localized in the area of inoculation along with the accumulation of phytoalexins. C. heterostrophus is a nonpathogen of sorghum and cytological studies indicated that cultivar DK18 is resistant to C. sublineolum, a sorghum pathogen. We demonstrated that the two fungi triggered different time courses of plant defense reactions. Inoculation with C. heterostrophus resulted in rapid accumulation of PR-10 and CHS transcripts...

  • cdna cloning of a sorghum pathogenesis related protein pr 10 and differential expression of defense related genes following inoculation with cochliobolus heterostrophus or colletotrichum sublineolum
    Molecular Plant-microbe Interactions, 1999
    Co-Authors: John Hipskind, Ralph L. Nicholson
    Abstract:

    A sorghum cDNA clone was isolated by differential screening of a cDNA library prepared from Mesocotyls (cultivar DK18) inoculated with fungal pathogenes. The deduced translation product shows sequence similarity to a family of intracellular pathogenesis-related proteins (PR-10) with a potential ribonuclease function. We studied the accumulation of PR-10 and chalcone synthase (CHS) transcripts in Mesocotyls following inoculation with Cochliobolus heterostrophus or Colletotrichum sublineolum. CHS is involved in phytoalexin synthesis in sorghum. Coordinate expression of PR-10 and CHS genes was localized in the area of inoculation along with the accumulation of phytoalexins. C. heterostrophus is a nonpathogen of sorghum and cytological studies indicated that cultivar DK18 is resistant to C. sublineolum, a sorghum pathogen. We demonstrated that the two fungi triggered different time courses of plant defense reactions. Inoculation with C. heterostrophus resulted in rapid accumulation of PR-10 and CHS transcripts after appressoria had become mature. Accumulation of these transcripts was delayed in plants inoculated with C. sublineolum until penetration of host tissue had been completed and infection vesicles had formed. Results suggest that different recognition events are involved in the expression of resistance to the two fungi used or that C. sublineolum suppresses the nonspecific induction of defense responses.

John Hipskind - One of the best experts on this subject based on the ideXlab platform.

  • cdna cloning of a sorghum pathogenesis related protein pr 10 and differential expression of defense related genes following inoculation with cochliobolus heterostrophus or colletotrichum sublineolum
    Molecular Plant-microbe Interactions, 1999
    Co-Authors: Szechung Clive Lo, John Hipskind, Ralph L. Nicholson
    Abstract:

    A sorghum cDNA clone was isolated by differential screening of a cDNA library prepared from Mesocotyls (cultivar DK18) inoculated with fungal pathogens. The deduced translation product shows sequence similarity to a family of intracellular pathogenesis-related proteins (PR-10) with a potential ribonuclease function. We studied the accumulation of PR-10 and chalcone synthase (CHS) transcripts in Mesocotyls following inoculation with Cochliobolus heterostrophus or Colletotrichum sublineolum. CHS is involved in phytoalexin synthesis in sorghum. Coordinate expression of PR-10 and CHS genes was localized in the area of inoculation along with the accumulation of phytoalexins. C. heterostrophus is a nonpathogen of sorghum and cytological studies indicated that cultivar DK18 is resistant to C. sublineolum, a sorghum pathogen. We demonstrated that the two fungi triggered different time courses of plant defense reactions. Inoculation with C. heterostrophus resulted in rapid accumulation of PR-10 and CHS transcripts...

  • cdna cloning of a sorghum pathogenesis related protein pr 10 and differential expression of defense related genes following inoculation with cochliobolus heterostrophus or colletotrichum sublineolum
    Molecular Plant-microbe Interactions, 1999
    Co-Authors: John Hipskind, Ralph L. Nicholson
    Abstract:

    A sorghum cDNA clone was isolated by differential screening of a cDNA library prepared from Mesocotyls (cultivar DK18) inoculated with fungal pathogenes. The deduced translation product shows sequence similarity to a family of intracellular pathogenesis-related proteins (PR-10) with a potential ribonuclease function. We studied the accumulation of PR-10 and chalcone synthase (CHS) transcripts in Mesocotyls following inoculation with Cochliobolus heterostrophus or Colletotrichum sublineolum. CHS is involved in phytoalexin synthesis in sorghum. Coordinate expression of PR-10 and CHS genes was localized in the area of inoculation along with the accumulation of phytoalexins. C. heterostrophus is a nonpathogen of sorghum and cytological studies indicated that cultivar DK18 is resistant to C. sublineolum, a sorghum pathogen. We demonstrated that the two fungi triggered different time courses of plant defense reactions. Inoculation with C. heterostrophus resulted in rapid accumulation of PR-10 and CHS transcripts after appressoria had become mature. Accumulation of these transcripts was delayed in plants inoculated with C. sublineolum until penetration of host tissue had been completed and infection vesicles had formed. Results suggest that different recognition events are involved in the expression of resistance to the two fungi used or that C. sublineolum suppresses the nonspecific induction of defense responses.

  • cDNA cloning of a sorghum pathogenesis-related protein (PR-10) and differential expression of defense-related genes following inoculation with Cochliobolus heterostrophus or Colletotrichum sublineolum
    'Scientific Societies', 1999
    Co-Authors: Lo Scc, John Hipskind, R. L. Nicholson
    Abstract:

    A sorghum cDNA clone was isolated by differential screening of a cDNA library prepared from Mesocotyls (cultivar DK18) inoculated with fungal pathogens. The deduced translation product shows sequence similarity to a family of intracellular pathogenesis-related proteins (PR-10) with a potential ribonuclease function. We studied the accumulation of PR-10 and chalcone synthase (CHS) transcripts in Mesocotyls following inoculation with Cochliobolus heterostrophus or Colletotrichum sublineolum. CHS is involved in phytoalexin synthesis in sorghum. Coordinate expression of PR-10 and CHS genes was localized in the area of inoculation along with the accumulation of phytoalexins. C. heterostrophus is a nonpathogen of sorghum and cytological studies indicated that cultivar DK18 is resistant to C. sublineolum, a sorghum pathogen. We demonstrated that the two fungi triggered different time courses of plant defense reactions. Inoculation with C. heterostrophus resulted in rapid accumulation of PR-10 and CHS transcripts after appressoria had become mature. Accumulation of these transcripts was delayed in plants inoculated with C. sublineolum until penetration of host tissue had been completed and infection vesicles had formed. Results suggest that different recognition events are involved in the expression of resistance to the two fungi used or that C. sublineolum suppresses the nonspecific induction of defense responses.link_to_subscribed_fulltex

Szechung Clive Lo - One of the best experts on this subject based on the ideXlab platform.

  • cdna cloning of a sorghum pathogenesis related protein pr 10 and differential expression of defense related genes following inoculation with cochliobolus heterostrophus or colletotrichum sublineolum
    Molecular Plant-microbe Interactions, 1999
    Co-Authors: Szechung Clive Lo, John Hipskind, Ralph L. Nicholson
    Abstract:

    A sorghum cDNA clone was isolated by differential screening of a cDNA library prepared from Mesocotyls (cultivar DK18) inoculated with fungal pathogens. The deduced translation product shows sequence similarity to a family of intracellular pathogenesis-related proteins (PR-10) with a potential ribonuclease function. We studied the accumulation of PR-10 and chalcone synthase (CHS) transcripts in Mesocotyls following inoculation with Cochliobolus heterostrophus or Colletotrichum sublineolum. CHS is involved in phytoalexin synthesis in sorghum. Coordinate expression of PR-10 and CHS genes was localized in the area of inoculation along with the accumulation of phytoalexins. C. heterostrophus is a nonpathogen of sorghum and cytological studies indicated that cultivar DK18 is resistant to C. sublineolum, a sorghum pathogen. We demonstrated that the two fungi triggered different time courses of plant defense reactions. Inoculation with C. heterostrophus resulted in rapid accumulation of PR-10 and CHS transcripts...

Riccardo Angelini - One of the best experts on this subject based on the ideXlab platform.

  • flavin containing polyamine oxidase is a hydrogen peroxide source in the oxidative response to the protein phosphatase inhibitor cantharidin in zea mays l
    Journal of Experimental Botany, 2006
    Co-Authors: Alessandra Cona, Rodolfo Federico, Federico Corelli, Maurizio Botta, Giuseppina Rea, Riccardo Angelini
    Abstract:

    In this study, the specific contribution of polyamine oxidase (PAO), a hydrogen peroxide (H2O2)-producing enzyme, to the oxidative burst induced in maize mesocotyl by the phosphatase inhibitor cantharidin was examined. For this purpose, a pharmacological approach was applied using, either in vitro or in vivo, two strong inhibitors of maize PAO (MPAO), N-prenylagmatine (G3) and its structural analogue Ro5, as well as diphenyleneiodonium (DPI), an inhibitor of the phagocyte NAD(P)H oxidase. DPI was shown to be a good MPAO inhibitor in vitro. G3, Ro5, and DPI were very effective in inhibiting in vivo the extracellular accumulation of H2O2 that is released by mesocotyl segments upon spermidine supply. G3 and Ro5 did not show any inhibition in vitro of either horseradish peroxidase or barley oxalate oxidase. Moreover, G3 and Ro5 did not inhibit the extracellular accumulation of superoxide radical that is released in vivo upon NADH supply. G3, Ro5, and DPI strongly affected H2O2 production induced in maize mesocotyl by cantharidin. Histochemical localization of H2O2 in cantharidin-treated mesocotyl cross-sections revealed an increase of H2O2-specific staining in the epidermal and subepidermal tissues. The effect was also inhibited by G3 and DPI. Moreover, an increase in MPAO activity was observed in the same tissues upon cantharidin treatment. All these data suggest that G3 and Ro5 behave as powerful and selective inhibitors of MPAO activity either in vitro or in vivo and that MPAO activity contributes to a major part of the cantharidin-induced H2O2 synthesis in the apoplastic milieu of maize mesocotyl.

  • Cellular re-distribution of flavin-containing polyamine oxidase in differentiating root and mesocotyl of Zea mays L. seedlings
    Planta, 2005
    Co-Authors: Alessandra Cona, Rodolfo Federico, Sandra Moreno, Francesco Cenci, Riccardo Angelini
    Abstract:

    Plant polyamine oxidases (PAOs; EC 1.5.3.11) are hydrogen peroxide-producing enzymes supposedly involved in cell-wall differentiation processes and defence responses. Maize ( Zea mays L.) PAO (MPAO) is a 53 kDa secretory glycoprotein, abundant in primary and secondary cell walls of several tissues. Using biochemical, histochemical, ultrastructural and immunocytochemical techniques, the distribution and sub-cellular compartmentalisation of MPAO in the primary root and mesocotyl of seedlings at different maturation stages or after growth under varying light conditions were analysed. In apical root tissues, MPAO immunoreactivity was mainly detected in the cytoplasmic compartment, while a lower immunoreactivity was observed in the cell walls. In the more mature, basal part of the root, intense immunogold labelling was found in the primary and secondary walls of protoxylem precursors and vessels, while endodermal cells and living metaxylem precursors were immunopositive both in their walls and in their thin cytoplasmic compartments. A re-distribution of MPAO protein from the cytoplasm toward the primary and secondary walls was also recognised when immunoreactivity of basal root tissues from 3-day-old seedlings was compared with that detected in 11-day-old tissues. Accordingly, biochemical analyses revealed MPAO entrapment in the extracellular matrix of mature tissues. In the mesocotyl, an enrichment of MPAO immunolabelling in the cell wall of protoxylem, metaxylem and epidermal tissues, as a function of light exposure, was observed. Taken together, these data support the hypothesised role of PAOs in cell-wall maturation. Moreover, the relevant intraprotoplasmic MPAO localisation observed mainly in differentiating root tissues suggests an additional role in intracellular production of hydrogen peroxide.

  • polyamine oxidase a hydrogen peroxide producing enzyme is up regulated by light and down regulated by auxin in the outer tissues of the maize mesocotyl
    Plant Physiology, 2003
    Co-Authors: Alessandra Cona, Manuela Cervelli, Paolo Mariottini, Rodolfo Federico, F Cenci, Sandra Moreno, Riccardo Angelini
    Abstract:

    Exogenously supplied auxin (1-naphthaleneacetic acid) inhibited light-induced activity increase of polyamine oxidase (PAO), a hydrogen peroxide-producing enzyme, in the outer tissues of maize ( Zea mays ) mesocotyl. The same phenomenon operates at PAO protein and mRNA accumulation levels. The wall-bound to extractable PAO activity ratio was unaffected by auxin treatment, either in the dark or after light exposure. Ethylene treatment did not affect PAO activity, thus excluding an effect of auxin via increased ethylene biosynthesis. The auxin polar transport inhibitors N 1 -naphthylphthalamic acid or 2,3,5-triiodobenzoic acid caused a further increase of PAO expression in outer tissues after light treatment. The small increase of PAO expression, normally occurring in the mesocotyl epidermis during plant development in the dark, was also inhibited by auxin, although to a lesser extent with respect to light-exposed tissue, and was stimulated by N 1 -naphthylphthalamic acid or 2,3,5-triiodobenzoic acid, thus suggesting a complex regulation of PAO expression. Immunogold ultrastructural analysis in epidermal cells revealed the association of PAO with the secretory pathway and the cell walls. The presence of the enzyme in the cell walls of this tissue greatly increased in response to light treatment. Consistent with auxin effects on light-induced PAO expression, the hormone treatment inhibited the increase in immunogold staining both intraprotoplasmically and in the cell wall. These results suggest that both light and auxin finely tune PAO expression during the light-induced differentiation of the cell wall in the maize mesocotyl epidermal tissues.

  • de etiolation causes a phytochrome mediated increase of polyamine oxidase expression in outer tissues of the maize mesocotyl a role in the photomodulation of growth and cell wall differentiation
    Planta, 1999
    Co-Authors: Maria Laurenzi, Paraskevi Tavladoraki, Rodolfo Federico, Giuseppina Rea, Riccardo Angelini
    Abstract:

    The photomodulation of polyamine oxidase (PAO) expression during de-etiolation of the maize (Zea mays L.) mesocotyl was used as the experimental model to investigate a possible correlation with the photomodulation of growth and with wall differentiation and stiffening. The accumulation of PAO transcript and enzyme activity were enhanced by light treatment in cortical and epidermal (outer) tissues of the mesocotyl. Histochemical analysis revealed that this phenomenon is mostly due to the increased level of PAO activity in epidermal and sub-epidermal tissues. The photomodulation of PAO activity upon de-etiolation in outer tissues is mediated by phytochrome. A close correlation was found between the time course of red-light-elicited increase of PAO activity and that of growth inhibition in the outer tissues of the apical, growing zone of the mesocotyl. Light exposure of etiolated, sub-apical mesocotyl segments resulted in a higher production of hydrogen peroxide (H2O2) in the incubation medium compared with segments incubated in the dark. The latter phenomenon was inhibited by the specific PAO inhibitor guazatine. A short pre-treatment of mesocotyl and coleoptile segments with 1 mM spermidine inhibited IAA-induced elongation growth, this phenomenon being reversed by catalase. Pre-treatment with catalase alone resulted in a higher extent of IAA-induced elongation. Moreover, pre-incubation with 1,3-diaminopropane, a product of spermidine oxidation catalysed by PAO, had no effect on IAA-induced elongation growth of either coleoptile or mesocotyl segments, while H2O2 pre-treatment was effective. These results indicate that PAO activity is important in producing H2O2 in vivo for peroxidase-catalysed wall-stiffening reactions and may be involved in the modulation of growth and cell wall differentiation in the maize mesocotyl.

Hajime Watanabe - One of the best experts on this subject based on the ideXlab platform.

  • identification of casparian bands in the mesocotyl and lower internodes of rice oryza sativa l seedlings using fluorescence microscopy
    Plant Production Science, 2006
    Co-Authors: Hajime Watanabe, Masahiko Saigusa, Shigenori Morita
    Abstract:

    The mesocotyl and lower internodes of seedlings are underground organs that play a possible role in water absorption and transport. The aim of this study is to reexamine and understand further the anatomy and morphology of Mesocotyls and lower internodes in rice, especially in terms of the existence of Casparian bands. Anatomical structures of mesocotyl and lower internodes tissue of rice seedlings were observed by light and fluorescence microscopy. The rice mesocotyl had two central cylinders, one is large and the other small, in the cross section. Casparian bands were observed in both the endodermis and exodermis of the mesocotyl, and also in the endodermis of the first internode. Furthermore, some bundles with intermediate xylem differentiation were observed between the exarch and endarch arrangement in the first internodes. Casparian bands were identified in the radial walls of cells surrounding each of these bundles. The second internode is quite similar to that of upper internodes in adult plants with respect to internal structure; scattered vascular bundles were seen as in monocotyledons. In the second internode, Casparian bands were seen in the radial cell walls of the bundle sheaths in each vascular bundle. Unlike the mesocotyl, Casparian bands were not observed in the hypodermis of the first or second internodes. The results show that the histological features of the mesocotyl and lower internodes of rice seedlings widely differed. In addition, the present study provides anatomical evidence for the existence of Casparian bands in both the mesocotyl and lower internodes of rice seedlings.

  • Morphological and anatomical effects of abscisic acid (ABA) and fluridone (FLU) on the growth of rice Mesocotyls
    Plant Growth Regulation, 2001
    Co-Authors: Hajime Watanabe, Kiyoshi Takahashi, Masahiko Saigusa
    Abstract:

    It has been reported that abscisic acid (ABA) promotes the growth ofrice Mesocotyls. We investigated the effects of ABA and fluridone (FLU), aninhibitor of ABA biosynthesis, on the morphological and anatomicalcharacteristics of the mesocotyl of dark-grown rice seedlings. By 5 days aftersowing (DAS), the mesocotyl of control seedlings had reached their a maximumlength of 50.0 mm. In ABA treated seedlings, the mesocotylcontinued growing until 12 DAS, reaching a length of 152.6 mm.Mesocotyls treated with FLU elongated until 4DAS attaining a final length ofonly 10.5 mm. The data indicated that the greater length ofMesocotyls in seedlings treated with ABA was mainly due to their longer growingperiod. An anatomical study showed that the cell division activity of themesocotyl localised near the coleoptilar node and that ABA prolonged the celldivision activity of the meristem. The results suggested that ABA regulates thegrowth of rice Mesocotyls by controlling the activity of the meristem localisednear the coleoptilar node.

  • Effects of abscisic acid, fusicoccin, and potassium on growth and morphogenesis of leaves and internodes in dark-grown rice seedlings
    Plant Growth Regulation, 1997
    Co-Authors: Hajime Watanabe, Kiyoshi Takahashi
    Abstract:

    We investigated the effects of abscisic acid (ABA), fusicoccin (FC) and potassium on the appearance of “MC” or “non-MC” type rice (Oryza sativa L.) seedlings. The MC type seedling referred to a seedling which only consisted of mesocotyl and coleoptile (the undeveloped leaves were enclosed by the coleoptile),whereas non-MC type seedling was the seedling consisted of greatly elongated leaves and internodes. Seedlings were grown on 0.8 % agar medium in the presence or absence of ABA, FC and KCl under aseptic conditions at 30 °C in the dark for 14 days. In cv. ‘Basmati 217’, MC type cultivar, 2 × 10^-2 M KCl or 10^-6 M FC both reduced the frequency of occurrence of the MC type seedlings among the investigated plants. Mesocotyl growth was inhibited about 45% by KCl and 90% by FC. In cv. 'JC 91', non-MC type cultivar, 1.5 × 10^-6 M ABA increased the percentage of the MC type seedlings and reduced coleoptile growth by 78% and second leaf growth by 87% However, during this treatment mesocotyl growth was stimulated by 195%. The effects of ABA were almost entirely overcome by FC. Thus, the action of these substances results in a drastic change in the morphological development of dark-grown rice seedlings. Since it has been reported that FC stimulates the development of K+ uptake coupled to H+ extrusion and ABA inhibits this function, we suggest that ABA and FC may regulate the morphogenesis of leaves and internodes of rice seedlings via the H+/K+ ion exchange system.