RESUMO
Solanum torvum is reported to carry resistance to bacterial wilt caused by Ralstonia solanacearum. So, this wild species is used as rootskock for eggplants or tomatoes in naturally infected soil. This study aimed to investigate the involvement of the polyamine metabolism pathway in the resistance mechanisms of this species. Calli induced from Solanum torvum stem explants were inoculated with the bacteria under partial vacuum. All calli showed a hypersensitive response after infiltration. Furthermore, amine oxidase activity with aldehyde and H(2)O(2) production was detected in soluble protein extracts of calli infiltrated by the bacteria. Due to its preferential affinity for aliphatic amines, this enzyme was supposed to have amine oxidase-like (AO-like) activity. Moreover, the length of aliphatic chain cycle altered the oxidative deamination kinetics of potential substrates. The AO-like catalytic activity was significantly inhibited by chelator agents such as ethylene-diamine-tretraacetic (EDTA), and also by semi-carbazide as aminoguanidine. These results suggested that (i) the prosthetic group of the AO-like enzyme could be a tyrosine-derived 6-hydroxytopaquinone structure, copper containing; (ii) this enzyme could be a semi-carbazide sensitive amine oxidase (SSAO).
Assuntos
Amina Oxidase (contendo Cobre)/metabolismo , Proteínas de Plantas/metabolismo , Caules de Planta/microbiologia , Ralstonia solanacearum/fisiologia , Solanum/microbiologia , Amina Oxidase (contendo Cobre)/química , Aminas/metabolismo , Biocatálise/efeitos dos fármacos , Quelantes/farmacologia , Ácido Edético/farmacologia , Formaldeído/metabolismo , Guanidinas/farmacologia , Interações Hospedeiro-Patógeno , Peróxido de Hidrogênio/metabolismo , Concentração de Íons de Hidrogênio , Cinética , Proteínas de Plantas/química , Caules de Planta/enzimologia , Caules de Planta/metabolismo , Poliaminas/metabolismo , Solanum/enzimologia , Solanum/metabolismo , Solubilidade , Especificidade por Substrato , Técnicas de Cultura de TecidosRESUMO
Calli induced from Solanum torvum stem explants were inoculated with Ralstonia solanacearum under partial vacuum. All calli showed a hypersensitive response after infiltration. Furthermore, amine oxidase activity with aldehyde and H(2)O(2) production was detected in semi-purified cell walls of calli infiltrated by the bacteria. Due to its preferential affinity for monoamines, this enzyme is supposed to have monoamine oxidase-like (MAO-like) activity. Moreover, the presence of hydroxyl radicals in the aromatic cycle alters the oxidative deamination kinetics of potential substrates. Indeed, the oxidation of dopamine (+2, OH) was shown to be faster than that of tyramine (+1, OH), which in turn was faster than that of phenylethylamine (0, OH). The MAO-like catalytic activity was significantly inhibited by some reducing agents such as sodium bisulphite and cysteine, and also by tryptamine under anaerobiosis. This latter result suggested that the prosthetic group of the MAO-like enzyme could be a tyrosine-derived 6-hydroxytopaquinone structure. Finally, the sigmoid kinetics of the MAO-like enzyme in semi-purified cell walls did not correspond to that expected for a purified MAO, suggesting that the kinetics were affected by some factors present in cell walls.