Effect of Growth Temperature on Leaf Nitrate Reductase, Glutamine Synthetase and NADH-Glutamate Dehydrogenase of Juvenile Maize Genotypes1
- J. A. Amos and
- R. L. Scholl2
Ten F1 hybrids of maize (Zea mays L.) grown at two day/night temperatures (35/25 C and 40/28 C) in controlled-environment chambers were assayed for in vitro nitrate reductase (NR) to compare the relative effect of high temperature on nitrate reductase activity (NRA) among hybrids. High temperature response of nitrate reductase was tested by assaying glutamine synthetase (GS) and NADH-glutamate dehydrogenase (GDH) from temperature-treated seedlings in a set of genotypes that differed for the degree of high temperature stability of nitrate reductase. The NRA of most hybrids was reduced approximately 35% by high temperature, and the overall genetic variability of NRA for temperature stability was low. However, the NRA of some hybrids, such as ‘A632Ht Χ B37Ht’, was depleted less by high temperature (22 and 17% reduction in two experiments, respectively) than others, such as ‘Oh51A Χ Oh551Χ (54 and 31% reduction), indicating that genotypic differences can occasionally be large. Genotypic variability for NR response to temperature was not correlated with that for GS or GDH, neither of which activities were reduced significantly by high temperature in any of six genotypes. The effect on NR of the addition of protein to the NR extraction medium was tested using tissue from seedlings grown at high and low temperatures. This addition had no detectable influence on the apparent temperature stability of genotypes. Protein addition, however, did slightly increase NRA of some of the genotypes. Increases of NRA due to addition of bovine serum albumin ranged from 0 to 30%Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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