Phosphoglucomutase activity during development of wheat grains

Phosphoglucomutase (PGM) activity was measured during the development of en dosperm of spring wheat (Triticum aestivum L. cv. Axona) in crude extracts and in isolated amyloplasts. Results show a 60% reduction in activity of pl astidial 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.