VIEW ARTICLE

Anti-Senescent Compounds Reduce Injury and Steroid Changes in Ozonated Leaves and Their Chloroplasts. Harley Tomlinson, Assistant Plant Pathologist, Department of Plant Pathology and Botany, The Connecticut Agricultural Experiment Station, New Haven 06504; Saul Rich, Chief Plant Pathologist, Department of Plant Pathology and Botany, The Connecticut Agricultural Experiment Station, New Haven 06504. Phytopathology 63:903-906. Accepted for publication 23 January 1973. DOI: 10.1094/Phyto-63-903.

Whole tissue and chloroplasts from leaves exposed to ozone (0.5 µliters/liter) for 1 hr, contained less free sterol and more sterol glycoside and acylated sterol glycoside than did tissue and chloroplasts from nonozonated leaves. Chloroplasts from bean leaves contained 40% of the total free sterol in whole leaf tissue. Ozone decreased the free sterol content of leaves and chloroplasts 25 and 21%, respectively. Chloroplasts from spinach leaves contained 37% of the total free sterol. The free sterol content of whole tissue and chloroplasts of spinach was decreased 44 and 39%, respectively, after ozonation. Intact bean plants and leaves treated with the anti-senescence compounds benzimidazole, N-6-benzyladenine, and kinetin, were resistant to ozone injury and did not lose free sterol. Resistance to ozone injury was induced only by those concentrations of chemical treatments that inhibited the degradation of chlorophyll.