RESUMEN
The results of several experiments concerning the presence and composition of alkaloids in different tissues (stems, leaves, roots) of Catharanthus roseus L. plants and explants, healthy and infected by clover phyllody phytoplasmas, are reported. The alkaloids extracted and determined by the reverse phase high-pressure liquid chromatography were vindoline, ajmalicine, serpentine, vinblastine, and vincristine. The total alkaloid concentration was higher in infected plants than in the controls, in particular the increase of vinblastine in infected roots was very significant. The ultrastructural observations of infected roots showed alterations of the cell walls and of the nuclei. These results demonstrate that phytoplasmas, detected in all infected tissues by light fluorescence and transmission electron microscopy, play an important role on secondary metabolism of the diseased plants, modifying both the total content of alkaloids and their ratio.
Asunto(s)
Alcaloides/metabolismo , Catharanthus/microbiología , Phytoplasma/crecimiento & desarrollo , Vinblastina/análogos & derivados , Yohimbina/análogos & derivados , Alcaloides/análisis , Catharanthus/citología , Catharanthus/metabolismo , Núcleo Celular/microbiología , Núcleo Celular/patología , Núcleo Celular/ultraestructura , Pared Celular/microbiología , Pared Celular/patología , Pared Celular/ultraestructura , Cromatografía Líquida de Alta Presión , Microscopía Electrónica , Microscopía Fluorescente , Phytoplasma/ultraestructura , Enfermedades de las Plantas/microbiología , Hojas de la Planta/química , Hojas de la Planta/metabolismo , Hojas de la Planta/microbiología , Raíces de Plantas/citología , Raíces de Plantas/metabolismo , Raíces de Plantas/microbiología , Brotes de la Planta/química , Brotes de la Planta/metabolismo , Brotes de la Planta/microbiología , Tallos de la Planta/citología , Tallos de la Planta/metabolismo , Tallos de la Planta/microbiología , Alcaloides de Triptamina Secologanina/análisis , Vinblastina/análisis , Vinblastina/metabolismo , Vincristina/análisis , Vincristina/metabolismo , Yohimbina/análisis , Yohimbina/metabolismoRESUMEN
The alterations of cell walls and the localization of several compounds such as polyphenols, suberin, lignin, in plum and apple plants infected with plum leptonecrosis (PLN) and apple proliferation (AP) phytoplasmas respectively, were investigated. Catharanthus roseus plants, infected with AP or PLN were also studied. The 4,6-diamidino-2-phenylindole (DAPI) test and transmission electron microscopy showed the presence of phytoplasmas in all infected plants. Specific histological stainings for cutinized/suberinized cell walls, tannin deposits and vacuolar polyphenol inclusions, performed on leaf and stem tissues, revealed an increase of these substances in infected plum and apple plants. No differences occurred in C. roseus. Total polyphenol analysis confirmed a strong increase (3-fold) in the polyphenol content in infected tissues, particularly in plum leaves. From the data obtained it appears that polyphenols can be considered as defence-related metabolites in plum and apple plants infected by phytoplasmas. Further investigations are necessary to determine whether these compounds play a specific role in the development of all phytoplasma/host interactions and in the defence-related processes.