Phosphoglucomutase Activity During Development of Wheat Grains

Summary Phosphoglucomutase (PGM) activity was measured during the development of endosperm of spring wheat ( Triticum aestivum L. cv. Axona) in crude extracts and in isolated amyloplasts. Results show a 60 % reduction in activity of plastidial PGM activity between 5 and 15 days post anthesis. Measurements of the concentrations of the substrates and co-factors of the PGM reaction in the tissue during this period indicate that the enzyme should be saturated in vivo , suggesting that the reduction in activity of PGM during endosperm development is a function of the amount of PGM protein. The implications of this for starch synthesis are discussed.