THE ROLE OF THE GLUTATHIONE SYSTEM DURING DEHYDRATION OF BOEA-HYGROSCOPICA

Plants of Boea hygroscopica F. Muell were subjected to dehydration for 25 days until the relative water content was 23%. The rate of water l oss was very slow during the first 12 days of dehydration while it dra matically increased during the last 3 days of the treatment. On day 12 of dehydration total glutathione content was reduced to 24% of the co ntrol level and was mainly present in the oxidized form. At that time an oxidation of the sulfhydryl groups of soluble proteins was observed . A protection of glutathione against oxidation of the sulfhydryl grou ps of soluble proteins was established only after 22 days of desiccati on, at the same time as glutathione began to accumulate. During the wh ole desiccation period enzyme activities related to glutathione utiliz ation and regeneration and the activity of NADP(+)-dependent glycerald ehyde-3-phosphate dehydrogenase (EC 1.2.1.12), which contains essentia l sulfhydryl groups, were maintained. The results of the present exper iment suggest that during dehydration of Boea hygroscopica glutathione has, above all, a primary role in the protection of the sulfhydryl gr oups of the thylakoid proteins, which were maintained in the reduced f orm during the whole dehydration period.