Differential effects of H2S on cytoplasmic and nuclear thiol concentrations in different tissues of Brassica roots

H2S-fumigation experiments with the sulphur-demanding plant Brassica oleracea L. (hybrid curly kale) were carried out to modulate glutathione levels in root tip cells. Plants were exposed in small fumigation cabinets to 0.4 μl l–1 H2S for 96 h. The data obtained by HPLC analysis of bimane-labeled thiols showed a slight increase of glutathione contents of about 20% in the roots of H2S fumigated plants. The histochemical non-destructive assay for the determination of glutathione in single cells of whole plant organs was carried out for the first time by the use of monochlorobimane (BmCl) in situ to give a fluorescent GSH–bimane conjugate, followed by a fixation procedure. A significant increase of the fluorescence signal after the H2S treatment was localized in the cytoplasm as well as in the nucleoplasm of root meristem cells.