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Peroxidase Enzyme Markers for Ozone Sensitivity in Sweet Corn. Edward V. Podleckis, Former graduate research assistant, Department of Plant Science, University of Delaware, Newark 19711, now at Department of Botany, University of Maryland, College Park 20742; Charles R. Curtis(2), and Howard E. Heggestad(3). (2)Formerly professor of plant pathology, University of Delaware, Newark 19711, now at Department of Plant Pathology, Ohio State University, Columbus, OH 43210, and (3)Research plant pathologist, Plant Stress Lab, Plant Physiology Institute, USDA, Beltsville, MD 20705. Phytopathology 74:572-577. Accepted for publication 2 February 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-572.

Fifteen inbreds and five hybrids of sweet corn (Zea mays) were evaluated for seedling sensitivity to a single acute ozone exposure. Seedlings at the three- to four-leaf stage were exposed to 492 μg/m3 (25 pphm) ozone for 3 hr in a controlled environment chamber. Plants were visually rated for ozone sensitivity. Three genotypes, including the commercially important hybrid Silver Queen, were relatively sensitive. Four lines were ranked highly resistant and the remaining 13 were rated intermediate. Polyacrylamide gel isoelectric focusing was used to compare the protein banding patterns of sensitive, resistant, and intermediate lines. Peroxidase and general protein banding patterns were examined. Stepwise multiple regression analysis was used to construct models for predicting ozone sensitivity from the banding patterns. The model based on general protein banding patterns produced an unacceptably high error and variability. The peroxidase model accurately predicted the relative sensitivity of eight of 10 genotypes examined and shows promise as a screening technique for ozone sensitivity.