VIEW ARTICLE

Physiology and Biochemistry

Effect of High Temperature Stress on Peroxidase Activity and Electrolyte Leakage in Maize in Relation to Sporulation of Bipolaris maydis Race T. M. O. Garraway, Professor, Department of Plant Pathology, Ohio Agricultural Research and Development Center and The Ohio State University, Columbus 43210; M. Akhtar(2), and E. C. W. Wokoma(3). (2)Post-doctoral researcher, Department of Plant Pathology, Ohio Agricultural Research and Development Center and The Ohio State University, Columbus 43210, Present address: Institute for Microbial and Biochemical Technology, USDA Forest Service, Forest Products Laboratory, Madison, WI 53705; (3)Assistant lecturer, Faculty of Biological Sciences, University of Port Harcourt, Rivers State, Nigeria. Phytopathology 79:800-805. Accepted for publication 13 February 1989. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/Phyto-79-800.

Exposure of maize (Zea mays L.) leaves to high temperature stress, i.e., 42 C for 6 hr before inoculation with Bipolaris maydis race T followed by incubation in the dark at 28 C for 24 hr, resulted in a significant decrease in peroxidase activity in both resistant and susceptible isolines compared with the control (leaves not exposed to high temperature stress before inoculation). Also at 48 hr of incubation, high temperature stress before inoculation decreased peroxidase activity compared with the control in the resistant but not in the susceptible isoline. Moreover, the level of peroxidase activity in high temperature stress-treated and control leaves was significantly lower in the susceptible than in the resistant isoline 48 hr after inoculation. Exposure to high temperature stress resulted in a significant increase in electrolyte leakage as well as in sporulation in both isolines. Maize leaf extracts containing peroxidase activity as well as leachates from leaves of both isolines exposed to high temperature stress caused an increase in sporulation in vitro. Whereas increased sporulation on maize leaves in response to high temperature stress appeared to be related to increased electrolyte leakage, such a relationship was not found with high temperature stress-induced changes in maize peroxidase.