RESUMEN
MAIN CONCLUSION: Nitro/oxidative modifications of proteins and RNA nitration resulted from altered peroxynitrite generation are elements of the indirect mode of action of canavanine and meta-tyrosine in plants Environmental conditions and stresses, including supplementation with toxic compounds, are known to impair reactive oxygen (ROS) and reactive nitrogen species (RNS) homeostasis, leading to modification in production of oxidized and nitrated derivatives. The role of nitrated and/or oxidized biotargets differs depending on the stress factors and developmental stage of plants. Canavanine (CAN) and meta-tyrosine (m-Tyr) are non-proteinogenic amino acids (NPAAs). CAN, the structural analog of arginine, is found mostly in seeds of Fabaceae species, as a storage form of nitrogen. In mammalian cells, CAN is used as an anticancer agent due to its inhibitory action on nitric oxide synthesis. m-Tyr is a structural analogue of phenylalanine and an allelochemical found in root exudates of fescues. In animals, m-Tyr is recognized as a marker of oxidative stress. Supplementation of plants with CAN or m-Tyr modify ROS and RNS metabolism. Over the last few years of our research, we have collected the complex data on ROS and RNS metabolism in tomato (Solanum lycopersicum L.) plants exposed to CAN or m-Tyr. In addition, we have shown the level of nitrated RNA (8-Nitro-guanine) in roots of seedlings, stressed by the tested NPAAs. In this review, we describe the model of CAN and m-Tyr mode of action in plants based on modifications of signaling pathways induced by ROS/RNS with a special focus on peroxynitrite induced RNA and protein modifications.
Asunto(s)
Aminoácidos/metabolismo , Ácido Peroxinitroso/metabolismo , Transducción de Señal/efectos de los fármacos , Solanum lycopersicum/metabolismo , Canavanina/metabolismo , Nitratos/metabolismo , Oxidación-Reducción , Estrés Oxidativo , Especies de Nitrógeno Reactivo/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Plantones/metabolismoRESUMEN
A non-protein amino acid (NPAA) - meta-Tyrosine (m-Tyr), is a harmful compound produced by fescue roots. Young (3-4 days old) tomato (Solanum lycopersicum L.) seedlings were supplemented for 24-72 h with m-Tyr (50 or 250 µM) inhibiting root growth by 50 or 100%, without lethal effect. Fluorescence of DAF-FM and APF derivatives was determined to show reactive nitrogen species (RNS) localization and level in roots of tomato plants. m-Tyr-induced restriction of root elongation growth was related to formation of nitrated proteins described as content of 3-nitrotyrosine. Supplementation with m-Tyr enhanced superoxide radicals generation in extracts of tomato roots and stimulated protein nitration. It correlated well to increase of fluorescence of DAF-FM derivatives, and transiently stimulated fluorescence of APF derivatives corresponding respectively to NO and ONOO- formation. Alterations in RNS formation induced by m-Tyr were linked to metabolism of nitrosoglutathione (GSNO). Activity of nitrosoglutatione reductase (GSNOR), catalyzing degradation of GSNO was enhanced by long term plant supplementation with m-Tyr, similarly as protein abundance, while transcripts level were only slightly altered by tested NPAA. We conclude, that although in animal cells m-Tyr is considered as a marker of oxidative stress, its secondary mode of action in tomato plants involves perturbation in RNS formation, alteration in GSNO metabolism and modification of protein nitration level.
Asunto(s)
Aldehído Oxidorreductasas/metabolismo , Proteínas de Plantas/metabolismo , Raíces de Plantas/efectos de los fármacos , Especies de Nitrógeno Reactivo/metabolismo , Solanum lycopersicum/efectos de los fármacos , Tirosina/farmacología , Solanum lycopersicum/enzimología , Microscopía Confocal , Óxido Nítrico/metabolismo , Raíces de Plantas/enzimología , Raíces de Plantas/metabolismo , Tirosina/químicaRESUMEN
MAIN CONCLUSION: NO donors and Arg remove dormancy of apple embryos and stimulate germination. Compounds lowering NO level (cPTIO, L -NAME, CAN) strengthen dormancy. Embryo transition from dormancy state to germination is linked to increased nitric oxide synthase (NOS)-like activity. Germination of embryos is associated with declined level of biotin containing proteins and nitrated proteins in soluble protein fraction of root axis. Pattern of nitrated proteins suggest that storage proteins are putative targets of nitration. Nitric oxide (NO) acts as a key regulatory factor in removal of seed dormancy and is a signal necessary for seed transition from dormant state into germination. Modulation of NO concentration in apple (Malus domestica Borkh.) embryos by NO fumigation, treatment with NO donor (S-nitroso-N-acetyl-D,L-penicillamine, SNAP), application of 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), N ω-nitro-L-arginine methyl ester (L-NAME), canavanine (CAN) or arginine (Arg) allowed us to investigate the NO impact on seed dormancy status. Arg analogs and NO scavenger strengthened embryo dormancy by lowering reactive nitrogen species level in embryonic axes. This effect was accompanied by strong inhibition of NOS-like activity, without significant influence on tissue NO2 (-) concentration. Germination sensu stricto of apple embryos initiated by dormancy breakage via short term NO treatment or Arg supplementation were linked to a reduced level of biotinylated proteins in root axis. Decrease of total soluble nitrated proteins was observed at the termination of germination sensu stricto. Also modulation of NO tissue status leads to modification in nitrated protein pattern. Among protein bands that correspond to molecular mass of approximately 95 kDa, storage proteins (legumin A-like and seed biotin-containing protein) were identified, and can be considered as good markers for seed dormancy status. Moreover, pattern of nitrated proteins suggest that biotin containing proteins are also targets of nitration.
Asunto(s)
Malus/metabolismo , Óxido Nítrico/metabolismo , Latencia en las Plantas , Proteínas de Plantas/metabolismo , Semillas/metabolismo , Arginina/metabolismo , Benzoatos/farmacología , Biotinilación , Western Blotting , Inhibidores Enzimáticos/farmacología , Germinación/efectos de los fármacos , Imidazoles/farmacología , Malus/embriología , NG-Nitroarginina Metil Éster/farmacología , Nitratos/metabolismo , Donantes de Óxido Nítrico/farmacología , Óxido Nítrico Sintasa/antagonistas & inhibidores , Óxido Nítrico Sintasa/metabolismo , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/metabolismo , S-Nitroso-N-Acetilpenicilamina/farmacología , Semillas/efectos de los fármacos , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Factores de TiempoRESUMEN
Cyanamide is an allelochemical produced by hairy vetch (Vicia villosa Roth.). Its phyotoxic effect on plant growth was examined on roots of onion (Allium cepa L.) bulbs. Water solution of cyanamide (2-10 mM) restricted growth of onion roots in a dose-dependent manner. Treatment of onion roots with cyanamide resulted in a decrease in root growth rate accompanied by a decrease in accumulation of fresh and dry weight. The inhibitory effect of cyanamide was reversed by its removal from the environment, but full recovery was observed only for tissue treated with this chemical at low concentration (2-6 mM). Cytological observations of root tip cells suggest that disturbances in cell division may explain the strong cyanamide allelopathic activity. Moreover, in cyanamide-treated onion the following changes were detected: reduction of mitotic cells, inhibition of proliferation of meristematic cells and cell cycle, and modifications of cytoskeleton arrangement.
Asunto(s)
Cianamida/farmacología , Cebollas/efectos de los fármacos , Feromonas/farmacología , Ciclo Celular/efectos de los fármacos , División Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Citoesqueleto/efectos de los fármacos , Meristema/crecimiento & desarrollo , Mitosis/efectos de los fármacos , Cebollas/crecimiento & desarrollo , Raíces de Plantas/citología , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/crecimiento & desarrollo , Vicia/químicaRESUMEN
One commonly observed effect of phytotoxic compounds is the inhibition or delay of germination of sensitive seeds. Mustard (Sinapis alba L.) seeds were incubated with aqueous extracts of sunflower (Helianthus annuus L.) leaves. Although sunflower phytotoxins did not influence seed viability, extracts completely inhibited seed germination. Inhibition of germination was associated with alterations in reserve mobilization and generation of energy in the catabolic phase of germination. Degradation of lipids was suppressed by sunflower foliar extracts resulting in insufficient carbohydrate supply. The lack of respiratory substrates and decrease in energy (ATP) generation resulted in suppression of the anabolic phase of seed germination and ultimately growth inhibition.