Abstract
Morning glory (Ipomoea nil (L.) Roth), especially cultivar Scarlet O'Hara (SO), is known to be highly sensitive to ozone, however, little is investigated in its mechanisms for ozone damage. The accurate fact-finding fortified by the molecular mechanisms is needed to understand the effect of ozone to vegetation using morning glory as a sensitive bio-indicator. Ethylene emission from leaves of morning glory (SO) increased during the 9 h-exposure to 200 ppb ozone accompanied with appearance of visible foliar injury. Pre-treatment by 1-methylcyclopropene, an ethylene reception inhibitor, reduced visible foliar injury by 100 ppb ozone, but did not reduce injury by 200 ppb, compared with untreated plants. Ascorbate contents decreased during ozone exposure. These results suggest that involvement of ethylene in propagation of cell death is limited in morning glory, and that deterioration of antioxidant ability is caused by oxidative stress. Expression of genes involved in ozone responses is now being analyzed.
