Stress ethylene formation determines plant sensitivity to ozone

Abstract

Ozone has long been known to cause reductions in the yield of crops¹ although the precise mechanism of how this occurs is still unclear. Recently, ozone has also been suggested as being involved in the forest decline that has occurred in central Europe²—perhaps in combination with other atmospheric pollutants or with various environmental stresses such as chilling, mineral leaching, insect predation or disease. Consequently, it is desirable that the cellular mechanisms by which ozone is toxic to both crops and conifers, and how they might be modulated by other atmospheric pollutants or environmental stresses, are fully understood. Ethylene is normally produced by all plants and in trace amounts it may interact with other plant growth substances to coordinate a wide variety of developmental processes. However, when plants experience environmental stresses they respond by liberating larger amounts of ethylene—often called stress ethylene³. We have been able to demonstrate, using pea seedlings in an experimental fumigation system⁴, that the formation of stress ethylene determines the sensivity of plants to atmospheric levels of ozone and to suggest how other air pollutants may enhance ozone-mediated leaf injury.