EFFECT OF TEMPERATURE AND DAYLENGTH ON PEROXIDASE AND MALATE (NAD) DEHYDROGENASE ISOZYME COMPOSITION IN TOBACCO LEAF EXTRACTS

Tobacco plants were grown in controlled-environment chambers with night/day temperatures of 10/15 C., 20/25 C., and 30/35 C., and with light durations of 6 hr, 12 hr, and 18 hr. Peroxidases and malate (NAD) dehydrogenases were extracted from green leaf tissue and analyzed for isozyme patterns by disc electrophoresis. A total of 18 anodic peroxidase bands were distinguishable—each alteration in a single environmental variable producing a different isozyme profile. Malate (NAD) dehydrogenase isozyme profiles resulting from each environmental condition exhibited at least four major components, but differences in daylength and temperature conditions changed the relative banding intensities and shifted migration rates of some bands. The physiological implications of these findings are discussed.