Does Light Inhibit Ethylene Production in Leaves?

Abstract

The effect of light on the rate of ethylene production was monitored using 2 different techniques: leaf segments incubated in closed flasks versus intact plants in a flow-through open system. Three different plants were used, sunflower (Helianthus annuus), tomato (Lycopersicon esculentum), and soybean (Glycine max). Experiments were conducted in the presence and absence of 1-aminocyclopropane-1-carboxylic acid (ACC). In all 3 species studied, light strongly inhibits ethylene production when cut leaf segments are incubated in the presence of ACC in closed flasks. When ethylene measurements are made with ACC-sprayed intact plants using a continuous flow system, the effect of light on ethylene production is only marginal. In leaf segments of sunflower and soybean incubated only in distilled H2O in closed flasks, light promotes ethylene production. In tomato, there is no difference between the rate of ethylene production between light and darkness under such conditions. When measurements are made with intact plants in a continuous flow system, the rate of ethylene production is almost identical in light and darkness, in the 3 plants studied. The effect of light on cut leaf segments incubated in the presence of ACC in closed flasks can be attributed to the techniques used for these measurements. Light has little effect on ethylene production by intact plants in an open system.