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Neuhaus, Jean-Marc

Nom
Neuhaus, Jean-Marc
Affiliation principale
Fonction
Professeur ordinaire
Email
jean-marc.neuhaus@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/300

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  • Publication
    Accès libre
    Expression of β-1,3-glucanase and chitinase in healthy, stem-rust-affected and elicitor-treated near-isogenic wheat lines showingSr5-orSr24-specified race-specific rust resistance
    (1997)
    Münch-Garthoff, Sabine
    ;
    Neuhaus, Jean-Marc 
    ;
    Boller, Thomas
    ;
    Kemmerling, Birgit
    ;
    Kogel, Karl-Heinz
    Pathogenesis-related expression of the two antifungal hydrolases β-1,3-glucanase (EC 3.2.1.39) and chitinase (EC 3.2.1.14) was studied in wheat (Triticum aestivum L.) as part of the defence response to stem rust (Puccinia graminis f.sp.tritici; Pgt), mediated by the semi-dominantly acting resistance genes Sr5 and Sr24. Complete resistance (infection type 0), mediated by the Sr5 gene in cultivar Pre-Sr5, closely correlates with the hypersensitive response of penetrated cells at early stage of the interaction, when the first haustorium is formed. In contrast, cultivar Pre-Sr24 shows intermediate resistance (infection type 2–3) which is not directly linked to cell death. In both cases, the plant response included a rapid increase in β-1,3-glucanase activity between 24 and 48 h after inoculation. One main extracellular 30-kDa isoform of β -1,3-glucanase was present in both lines, as shown by polyacrylamide-gel electrophoresis. Two additional minor isoforms (32 and 23 kDa) were detected only in Pre- Sr24, and only at later time points. Increased enzyme activity and the appearance of new isoforms in the resistant lines was preceded by accumulation of mRNAs encoding β-1,3-glucanases and chitinases. However, there were no changes in chitinase activity or isoforms. A high constitutive level of chitinase activity was observed in all wheat genotypes. Serological studies indicated the presence of a class 11 chitinase of 26 kDa. Accumulation of β-1,3-glucanase and chitinase transcripts was detected before the pathogen penetrated the leaves through stomata and approximately 16 h before the typical hypersensitive response was observed, indicating that signal(s) for defense gene activation were recognised by the host plant long before a tight contact between the pathogen and a host cell is established. A glycoprotein (Pgt elicitor) derived from hyphal walls, strongly induced β-1,3-glucanase. We discuss the possible role of the elicitor in the early signalling mediating Sr5 and Sr24-specified resistance in wheat.
  • Publication
    Accès libre
    Plant chitinases use two different hydrolytic mechanisms
    (1996)
    Iseli, Beatrice
    ;
    Armand, Sylvie
    ;
    Boller, Thomas
    ;
    Neuhaus, Jean-Marc 
    ;
    Henrissat, Bernard
    Bacterial, fungal, animal, and some plant chitinases form family 18 of glycosyl hydrolases. Most plant chitinases form the family 19. While some chitinases also have lysozyme activity, animal lysozymes belong to different families. For glycosyl hydrolases, two reaction mechanisms are possible, leading to either retention or inversion of the anomeric configuration. We analyzed by HPLC the stereochemical outcome of the hydrolysis catalyzed by cucumber and bean chitinases, belonging to families 18 and 19, respectively. Cucumber chitinase used the retaining mechanism as known for bacterial chitinases and hen egg white lysozyme for which the mechanism has been determined. In contrast, bean chitinase catalyzed the hydrolysis of chitooligosaccharides with overall inversion of anomeric configuration.
  • Publication
    Métadonnées seulement