Activity Changes in Selected Enzymes from Soybean Leaves Following Ozone Exposure

Abstract

Abstract Soybeans [ Glycine max (L.) Merr.] were harvested at various time periods after a 2‐h exposure to either 0 or 0.5 μ1/1 ozone to determine the effects of ozone on selected enzymes. Carbohydrate metabolism was modified by a depression of glyceraldehyde 3‐phaosphate dehydrogenase and an activation of glucose 6‐phosphate dehydrogenase. Ozone did not alter the levels of RNase, protease, acid phosphatase or esterase as might be expected if ozone enhanced leaf senescence. The activities of phenylalanine ammonia lyase, polyphenol oxidase and peroxidase were initially depressed and then stimulated following the ozone exposure. The reactions of soybeans to an acute ozone stress were more nearly akin to those elicited in response to other stresses than to the process of senescence.