Régulateurs de croissance et potentiel de la féverole

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Hydrogen peroxide induces programmed cell death features in cultured tobacco BY-2 cells, in a dose-dependent manner

Active oxygen species (AOS), especially hydrogen peroxide, play a critical role in the defence of plants against invading pathogens and in the hypersensitive response (HR). This is characterized by the induction of a massive production of AOS and the rapid appearance of necrotic lesions is considered as a programmed cell death (PCD) process during which a limited number of cells die at the site of infection. This work was aimed at investigating the mode of cell death observed in cultures of BY-2 tobacco cells exposed to H(2)O(2). It was shown that H(2)O(2) is able to induce various morphological cell death features in cultured tobacco BY-2 cells. The hallmarks of cell death observed with fl…

Influence de la présence des gènes Rht1 et Rht2 (gènes de réduction de hauteur) sur la composition lipidique de plantules étiolées de blé

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Proteasome comprising a beta1 inducible subunit acts as a negative regulator of NADPH oxidase during elicitation of plant defense reactions.

Elicitation of defense reactions in tobacco by cryptogein, triggered a production of active oxygen species (AOS) via the NADPH oxidase, NtrbohD, and an accumulation of beta1din, a defense induced beta-type subunit of 20S proteasome. The proteasome inhibitor, MG132, stimulated this AOS production. Tobacco cells transformed with sense constructs of beta1din showed an inhibition of the AOS production following elicitin treatment, whereas the antisense transformed cells showed a strongly enhanced AOS production. In cells transformed with sense construct of beta1din, the NtrbohD transcripts failed to be induced by cryptogein as observed in control and antisense transformed cells. Conversely, in …

Cloning of two plant cDNAs encoling a beta-type proteasome subunit and a transformer-2-like SR-related protein: Early induction of the corresponding genes in tobacco cells treated with cryptogein

International audience

La lutte biologique. Vers de nouveaux équilibres écologiques

Isolation of partial length cDNAs corresponding to early differentially expressed genes during elicitation of tobacco cells by cryptogein : Use of differential mRNA display

International audience

Induction of tcI7, a gene encoding a beta-subunit of proteasome, in tobacco plants treated with elicitins, salicylic acid or hydrogen peroxide

International audience

Etude des mécanismes moléculaires impliqués dans les réponses de la plante à la lumière, aux phytohormones (en particulier les cytokinines), ainsi que dans les relations plante-pathogene

*INRA Laboratoire de phytopharmacie BP 86510 21065 Dijon cedex (FRA) Diffusion du document : INRA Laboratoire de phytopharmacie BP 86510 21065 Dijon cedex (FRA); National audience

Cryptogein affects expression of alpha3, alpha6 and bêta1 20S proteasome subunits encoding genes in tobacco

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Preferential induction of 20S proteasome subunits during elicitation of plant defense reactions: towards the characterization of "plant defense proteasomes".

Plants have evolved efficient mechanisms to resist pathogens. The earliest defense response is the hypersensitive response (HR) considered as the main step leading to plant systemic acquired resistance (SAR) that protects the whole plant against a large spectrum of pathogens. We showed previously that elicitation of defense reactions in tobacco cells by cryptogein, a proteinaceous elicitor of plant defense reactions, leads to a rapid and differential accumulation of transcripts corresponding to genes encoding defense-induced (din) subunits of 20S proteasome: beta1din, alpha3din and alpha6din.Here, expression of these three subunits was investigated by Northern blotting and by Western blotti…

Cryptogein affects expression of alpha3, alpha6 and beta1 20S proteasome subunits encoding genes in tobacco.

Twelve a and b 20S proteasome subunits cDNAs showing 70–82% identity with the corresponding genes in Arabidopsis or rice, and features of eukaryotic proteasome subunits were cloned in tobacco. Only b1-tcI 7, a3 and a6, 20S proteasome subunits encoding genes were up-regulated by cryptogein, a proteinaceous elicitor of plant defence reactions. These results led to the hypothesis that the activation of b1-tcI 7, a3 and a6 could induce a specific proteolysis involved in the hypersensitive response and systemic acquired resistance monitored by cryptogein. In eukaryotes, the 26S proteasome is the central multicatalytic proteinase complex comprising two subcomplexes: the 20S core particle that per…

Cytokinin affects nitrate reductase expression through the modulation of polyadenylation of the nitrate reductase mRNA transcript

Abstract Cytokinin (CK) and low-intensity light effects in modulating nitrate reductase (NR) activity, NR protein and NR encoding mRNAs were studied in tobacco cell suspension cultures. NR activity was strikingly enhanced by CK in dark- as well as in light-grown cells whereas it was less affected by light alone. NR protein accumulation was stimulated by the hormone in the light only; then a CK light-dependent regulation of NR activity was suggested. Light enhanced the steady-state levels of hybridisable total NR mRNA and a light-inductive effect was also observed after transfer from dark to light; this effect was dependent on sucrose supply and was enhanced in CK-supplied cells. NR poly(A) …

Interactions between phytochrome and chlorophyll biosynthesis

International audience

Mise en évidence et étude des interactions phytochrome - liposomes chez la courge (Cucurbita pepo L.) et le blé (Triticum aestivum L.)

150 ref. *INRA Dijon, Documentation, 17 rue Sully, BP 86510, 21065 Dijon cedex Diffusion du document : INRA Dijon, Documentation, 17 rue Sully, BP 86510, 21065 Dijon cedex Diplôme : Dr. d'Université

Induction of tcl 7, a gene encoding a beta-subunit of proteasome, in tobacco plants treated with elicitins, salicylic acid or hydrogen peroxyde

International audience

Involvement of Lipoxygenase-dependent Production of Fatty Acid Hydroperoxides in the Development of the Hypersensitive Cell Death induced by Cryptogein on Tobacco Leaves

Lipid peroxidation was investigated in relation with the hypersensitive reaction in cryptogein-elicited tobacco leaves. A massive production of free polyunsaturated fatty acid (PUFA) hydroperoxides dependent on a 9-lipoxygenase (LOX) activity was characterized during the development of leaf necrosis. The process occurred after a lag phase of 12 h, was accompanied by the concomitant increase of 9-LOX activity, and preceded by a transient accumulation of LOX transcripts. Free radical-mediated lipid peroxidation represented 10% of the process. Inhibition and activation of the LOX pathway was shown to inhibit or to activate cell death, and evidence was provided that fatty acid hydroperoxides ar…

Signal perception and transduction, secondary messengers and gene activation in elicitin-triggered HR and SAR in tobacco

National audience

In vitro interactions of squash and wheat phytochrome with multilamellar liposomes

National audience

Induction of tcI 7 , a gene encoding a β-subunit of proteasome, in tobacco plants treated with elicitins, salicylic acid or hydrogen peroxide 1

We previously isolated, by differential display and 5′ RACE (rapid amplification of cDNA ends), cDNAs corresponding to genes activated following cryptogein treatment of tobacco cell suspensions, among them tcI 7 (tcI for obacco ryptogein nduced), a gene encoding a β-subunit of proteasome. Here, we report that tcI 7 was up-regulated in tobacco plants treated with elicitins (cryptogein and parasiticein) that have been shown to induce a systemic acquired resistance (SAR). Moreover, subsequent inoculation of tobacco with the pathogen Phytophthora parasitica var. nicotianae (Ppn) was shown to induce an additional activation of tcI 7 in tobacco plants pretreated with cryptogein. We also showed an…