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1.
Physiol Plant ; 135(4): 351-64, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19292825

RESUMO

Infection with avirulent pathogens, tobacco mosaic virus (TMV) or Pseudomonas syringae pv. tabaci induced accumulation of polyisoprenoid alcohols, solanesol and a family of polyprenols [from polyprenol composed of 14 isoprene units (Pren-14) to -18, with Pren-16 dominating] in the leaves of resistant tobacco plants Nicotiana tabacum cv. Samsun NN. Upon TMV infection, solanesol content was increased seven- and eight-fold in the inoculated and upper leaves, respectively, while polyprenol content was increased 2.5- and 2-fold in the inoculated and upper leaves, respectively, on the seventh day post-infection. Accumulation of polyisoprenoid alcohols was also stimulated by exogenously applied hydrogen peroxide but not by exogenous salicylic acid (SA). On the contrary, neither inoculation of the leaves of susceptible tobacco plants nor wounding of tobacco leaves caused an increase in polyisoprenoid content. Taken together, these results indicate that polyisoprenoid alcohols might be involved in plant resistance against pathogens. A putative role of accumulated polyisoprenoids in plant response to pathogen attack is discussed. Similarly, the content of plastoquinone (PQ) was increased two-fold in TMV-inoculated and upper leaves of resistant plants. Accumulation of PQ was also stimulated by hydrogen peroxide, bacteria (P. syringae) and SA. The role of PQ in antioxidant defense in cellular membranous compartments is discussed in the context of the enzymatic antioxidant machinery activated in tobacco leaves subjected to viral infection. Elevated activity of several antioxidant enzymes (ascorbate peroxidase, guaiacol peroxidase, glutathione reductase and superoxide dismutase, especially the CuZn superoxide dismutase isoform) and high, but transient elevation of catalase was found in inoculated leaves of resistant tobacco plants but not in susceptible plants.


Assuntos
Álcoois/metabolismo , Nicotiana/metabolismo , Terpenos/metabolismo , Peróxido de Hidrogênio/farmacologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Folhas de Planta/microbiologia , Folhas de Planta/virologia , Plastoquinona/metabolismo , Pseudomonas syringae/fisiologia , Ácido Salicílico/farmacologia , Estresse Fisiológico , Nicotiana/efeitos dos fármacos , Nicotiana/microbiologia , Nicotiana/virologia , Vírus do Mosaico do Tabaco/fisiologia
2.
Acta Biochim Pol ; 52(1): 233-41, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15827620

RESUMO

In many plants belonging to angiosperms and gymnosperms the accumulation in leaves of long chain polyprenols and polyprenyl esters during growth in natural habitats depends on the light intensity. The amount of polyprenols in leaves is also positively correlated with the thickness of the leaf blade (SLA, specific leaf area). The polyprenol content of leaves shows seasonal changes with a maximum in autumn and a minimum in early summer with the difference between poorly and well illuminated plants persisting throughout the vegetation season.


Assuntos
Luz , Pentanóis/metabolismo , Folhas de Planta/metabolismo , Árvores/metabolismo , Cromatografia Líquida de Alta Pressão , Hemiterpenos , Estrutura Molecular , Pentanóis/química , Estações do Ano
3.
J Biol Chem ; 283(30): 21024-35, 2008 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-18502754

RESUMO

Plant isoprenoids are derived from two biosynthetic pathways, the cytoplasmic mevalonate (MVA) and the plastidial methylerythritol phosphate (MEP) pathway. In this study their respective contributions toward formation of dolichols in Coluria geoides hairy root culture were estimated using in vivo labeling with (13)C-labeled glucose as a general precursor. NMR and mass spectrometry showed that both the MVA and MEP pathways were the sources of isopentenyl diphosphate incorporated into polyisoprenoid chains. The involvement of the MEP pathway was found to be substantial at the initiation stage of dolichol chain synthesis, but it was virtually nil at the terminal steps; statistically, 6-8 isoprene units within the dolichol molecule (i.e. 40-50% of the total) were derived from the MEP pathway. These results were further verified by incorporation of [5-(2)H]mevalonate or [5,5-(2)H(2)]deoxyxylulose into dolichols as well as by the observed decreased accumulation of dolichols upon treatment with mevinolin or fosmidomycin, selective inhibitors of either pathway. The presented data indicate that the synthesis of dolichols in C. geoides roots involves a continuous exchange of intermediates between the MVA and MEP pathways. According to our model, oligoprenyl diphosphate chains of a length not exceeding 13 isoprene units are synthesized in plastids from isopentenyl diphosphate derived from both the MEP and MVA pathways, and then are completed in the cytoplasm with several units derived solely from the MVA pathway. This study also illustrates an innovative application of mass spectrometry for qualitative and quantitative evaluation of the contribution of individual metabolic pathways to the biosynthesis of natural products.


Assuntos
Dolicóis/química , Eritritol/análogos & derivados , Ácido Mevalônico/metabolismo , Plantas/metabolismo , Fosfatos Açúcares/metabolismo , Álcoois/química , Citoplasma/metabolismo , Eritritol/metabolismo , Glucose/química , Glucose/metabolismo , Espectroscopia de Ressonância Magnética , Espectrometria de Massas/métodos , Modelos Biológicos , Raízes de Plantas/metabolismo , Plastídeos/química , Plastídeos/metabolismo , Probabilidade , Espectrometria de Massas por Ionização por Electrospray/métodos , Esteróis/química
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