Cytological modifications in maize plants infected by barley yellow dwarf virus and maize dwarf mosaic virus

Three inbred lines of maize (33-16, MO17 and B73) differing in their susceptibility to Barley yellow dwarf virus and Maize dwarf mosaic virus were studied to compare the ultrastructural modifications induced by the two viruses in leaf tissues of different age. The results demonstrate that the alterations induced by the two viruses in the different maize lines could depend on the particular line tested.     

Cytochemical localization of calcium and X-ray microanalysis of Catharanthus roseus L. infected with phytoplasmas

The potassium pyroantimonate (KPA) Ca²⁺ precipitation technique, X-ray microanalysis and Electron Energy Loss Spectroscopy carried out by transmission electron microscopy were used to analyze the Ca²⁺ distribution in Catharanthus roseus L. leaves infected with phytoplasmas belonging to different taxonomic groups, and in phytoplasma cells. The analysis revealed that the distribution of Ca²⁺ was different in healthy and diseased plants (where the KPA deposits were numerous) and no differences were observed in the tissues of the three types of infected C. roseus L. Since no KPA precipitates were visible in the phloem and on phytoplasma cells, it is likely that Ca²⁺ ions are not directly involved in phytoplasma replication, but, in infected cells is a response to the pathogen indicative of a higher Ca²⁺ in the plasmalemma.