EFFECTS OF SULPHUR DIOXIDE ON BIOCHEMICAL ACTIVITY AND ULTRASTRURAL ORGANIZATION OF PINE NEEDLED CHOROPLASTS

Abstract

SUMMARY The effects of aqueous SO 2 on the ultrastructural organization of pine ( Pinus contorta Dougl. var. latifolia Engelm.) chloroplasts and on their photosynthetic activity were determined under laboratory conditions. At aqueous concentrations of 100 and 500 ppm, SO 2 caused swelling of thylakoid discs and disintegrated other intrachloroplast membranes, resulting in the formation of small vesicles (in older, matured tissues). Chloroplast structural injury was more pronounced in old tissues than in younger and more metabolically active tissues. The biochemical observations (Hill reaction activity) made on chloroplasts isolated from SO 2 ‐treated pine needle segments are in good agreement with the cytological observations.