Effect of elevated temperature on catalase and superoxide dismutase during maize development

Seeds of the inbred maize lines, W64A, R6–67, and D10, were germinated and grown at 25°, 35°, or 40° C for up to 10 days. The catalase activity in scutella of W64A seedlings grown at 40° C was slightly lower than that in seedlings grown at 25° C. The total superoxide dismutase activity in scutella was lower in seedlings grown at 40° C than in those grown at 25° C during the first 3 days of germination, but thereafter was not significantly different at these temperatures. The high-catalase mutant lines, R6–67 and D10, grown at 40° C exhibited a developmental pattern of catalase activity that was severalfold lower than that seen in seedlings grown at 25° C. The decrease in catalase activity in R6–67 seedlings grown at 40° C was correlated with lower amounts of CAT-2 protein, which is normally present at significantly high levels in this line. The application of a catalase synthesis inhibitor revealed that the low levels of CAT-2 in R6-67 grown at 40° C were due to slightly higher degradation rates and a significant drop in the rate of catalase protein synthesis.