Two-Dimensional Gel Electrophoretic Analysis of Chromatin-associated Proteins from Leaves of Different Species and Varieties of Nicotiana.

From different Nicotiana species (N. sylvestris Spegaz. et Comes, N. glutinosa L., and N. tabacum L. cultivars) which differ in their sensitivity towards tobacco mosaic virus (TMV), chromatin-associated protein profiles were compared by two-dimensional polyacrylamide gel electrophoresis. After removal of DNA from dissociated chromatin preparations, the remaining chromatin-associated proteins were extracted with phenol and precipitated with ethanol. The sensitive silver staining of the gel enabled visualization of up to 350 different polypeptides. Comparative analysis showed that over 90% of the polypeptides were similar in all Nicotiana species but discrete differences provided unique patterns for each of the species and cultivars examined. However, no specific polypeptide spot could be associated with the presence of the gene N, which governs hypersensitivity towards TMV. Nevertheless, the method presented here allows study of the chromatin proteins involved in the regulation of gene expression during growth and development, as well as analyses of the influence of environmental factors on genetic regulatory elements.