To compare the effects of ozone and peroxyacetyl nitrate (PAN) on leaf lipids, fatty acids and malondialdehyde (MDA), morning glory (Pharbitis nil Choisy cv Scarlet O'Hara) and kidney bean (Phaseolus vulgaris L. cv Gintebo) plants were exposed to either ozone (0.15 microliter per liter for 8 hours) or PAN (0.10 microliter per liter for up to 8 hours). Ozone increased phospholipids in morning glory and decreased in kidney bean at the initial stage (2-4 hours) of exposure, while it scarcely changed glycolipids, the unsaturated fatty acids, and MDA in both plants. A large reduction of glycolipids occurred 1 day after ozone exposure in both plants. PAN reacts with double bonds leading to the production of oxidation products (7). Indeed, Pauls and Thompson (19,20) have reported that chemical and physical changes in membrane lipids such as the breakdown of phospholipids, the loss of sterols from the membrane, and the formation of gel phase lipid membrane were induced by treating the isolated microsomal membrane from bean leaves with ozone in solution. However, the results obtained from isolated systems have not been confirmed in plant tissues.PAN reacts with the sulfhydryl group to form either disulfide or S-acetyl group and also reacts with olefine to form epoxides (14). Such reactions could affect the proteins and the lipids of membranes. Ozone not only destroys the double bond in unsaturated fatty acids, but also affects lipid biosynthesis (12, 13). Lipid synthesis from acetate and acetyl-CoA (12) and the incorporation of galactose from UDP-galactose into galactolipids (13) were inhibited by bubbling ozone through a chloroplast suspension. PAN in vitro also inhibited the synthesis of fatty acids from acetate (11). Thus, exposure to ozone and PAN seems to alter the membrane lipids in leaf tissues.The present study was initiated to compare the effects of ozone and PAN on the leaf lipids, fatty acids, and MDA of two different plants. Morning glory and 6 to 7 d old kidney bean plants were exposed to either ozone (0.15 ,ul/L for 8 h) or PAN (0.10 ,ul/L for 8 h) and then examined for changes in their fatty acids, polar lipids, and MDA that occurred immediately after or 24 h after the exposure periods.Morning glory and kidney bean are plants susceptible to ozone, and morning glory in particular has been used as an indicator plant of photochemical oxidants (ozone) in Japan (16 (65:25:4, v/v) and in the second direction with chloroform-methanol-isopropylamine-ammonium hydroxide (65:35:0.5:5, v/v) (1). The chromatogram was viewed under UV after spraying with 0.01% (w/ v) primuline in 80% acetone. Individual polar lipids were identified by co-chromatography with authentic standards and by their reaction with specific spray reagents of anthrone sulfuric acid, Dittmer, Dragendorff, ninhydrin, and iron (III) chloride specific to glycolipid, phospholipid, the choline group, the amino group, and sterol, respectively. Each fluorescent lipid area was scraped from the plate and subjected to methanolysis with 10% (w/v) sul...
