A powdery mildew disease was observed on leaves of Solanum gilo, S. melongena, S. tuberosum S. chacoense, Nicotiana rustica and N. tabacum in Brasília (Federal District), Brazil. Symptoms were mainly characterized by adaxial yellow areas in the leaves corresponding to white fungal colonies on the abaxial surface. Profuse sporulation was often observed. Light microscopy of the fungal colonies re...

Five millimolar KCN reduced water permeability in 1-millimeter thick slices of potato tuber (Solanum tuberosum L.). One-tenth millimolar ATP and CTP prevented or reversed the reduced permeability. UTP and GTP were not effective. Five millimolar ammonium carbonate or 0.1 millimolar 2,4-dinitrophenol also reduced water permeability, but ATP and CTP were only partially effective in reversing the r...

The time course and spatial distribution of wound-induced activities of phenylalanine ammonia-lyase and peroxidase were determined to establish correlations between molecular and cellular aspects of the wound-induced pattern of cell differentiation in potato (Solanum tuberosum L.) tissue. A high correlation between peroxidase activity and suberization was observed. Peroxidase activity increased...

Mesophyll cell protoplasts were isolated from potato (Solanum tuberosum L. cv. Russet Burbank) leaves and induced to proliferate in culture. Protoplast division was observed only among preparations isolated from plants previously conditioned under short periods of low intensity illumination. Sustained growth and development of protoplast-derived calli (p-calli) occurred when they were maintaine...

the use of healthy planting material is an important prerequisite for controlling destructive viral diseases in potato production. virus elimination methods such as meristem culture and thermotherapy are usually used to produce the nucleus stock of healthy planting material. here, we report a new technique of electrotherapy for elimination of two potyviruses, potato virus a (pva), and potato vi...