Diurnal, seasonal, and genotypic variation of sucrose phosphate synthetase from maize leaf blades

Abstract

Sucrose phosphate synthetase (SPS) activity of leaf blades from seven inbred lines of maize ( Zea mays L.) was monitored throughout the growing season. Activity was low during the first part of the season, steadily increased until tassel emergence, and then declined. Some genotypes showed a second minor peak of SPS activity during ear fill. Differences among the genotypes were most apparent near tasselling. During a 24-h period, peaks in SPS activity were observed at approx. 1600 and 0200 hours. The possibility that SPS, glucose-6-phosphate dehydrogenase (G-6-PDH), and phosphofructokinase (PFK) may compete for hexose-phosphates in discussed.