The Basis for Different Sensitivities of Photosynthesis to SO2in Two Cultivars of Pea

Abstract

Alscher, R., Bower, J. L. and Zipfel, W. 1987. The basis for different sensitivities of photosynthesis to SO₂ in two cultivars of pea.—J. exp. Bot. 38: 99–108. The response of several physiological parameters to exposure to SO₂ (0·8 ppm and 0·6 ppm) was studied in two cultivars of Pisum sativum in which photosynthesis showed a different sensitivity to SO₂. Leaf conductance was slightly reduced during exposure to SO₂ in the sensitive but not the insensitive cultivar. More sulphite accumulated in the leaves of the sensitive than in those of the insensitive cultivar. Total leaf content of reduced glutathione in the insensitive cultivar increased during exposure to SO₂, while in the sensitive cultivar there was no increase until the post-exposun period. The activities of fructose l,6-bisphosphatase and glyceraldehyde-3-phosphate dehydrogenase did not decrease greatly in either cultivar, although activities of enzymes from the sensitive cultivar were more affected by SO₂ than were those of the insensitive cultivar. Exposure to SO₂ also had little effect on either coupled or uncoupled electron transport of isolated thylakoids from the leaves of either cultivar. Increased glutathione in the insensitive cultivar may protect the photosynthetic apparatus against SO₂