Differential Effects of Ozone and Sulphur Dioxide on the Fine Structure of Spinach Leaf Cells

Summary Spinach (Spinacia oleraceaL. cv, New Asia) plants were continuously fumigated with 0.5 μ11−2O3and 1.0 μ11−1SO2singly or in combination. The leaf tissues were examined by electron microscopy at various intervals until they were necrosed. The first indication of O3injury was swelling of thylakoids in the chloroplasts, which was followed by swelling of Golgi bodies, endoplasmic reticulum and nuclear envelopes. The internal space of the mitochondrial cristae was reduced. Later the chloroplasts were deformed. Sulphur dioxide injury first appeared as swelling of the stroma and deformation of the chloroplasts. Swelling of thylakoids appeared later. After both treatments the ceils ultimately collapsed and their contents were aggregated. When O3and SO2were supplied simultaneously, the appearance and development of injury were markedly accelerated compared with either of the single fumigations. The cells mainly showed the features of SO2injury following simultaneous fumigation.