Nucleotide pyrophosphatase activity in dry and germinated seeds of Triticum, and its relationship to general acid phosphatase activity

A cytochemical investigation has been made of nucleotide pyrophosphatase activity in dry and germinated seeds of Triticum, and its distribution compared to that of general acid phosphatase reactions seen with naphthol AS-BI phosphate and p-nitrophenylphosphate as substrates. Acid phosphatase activity was present in the cytoplasm and in channels through the walls of the aleurone cells in both dry and germinated seeds. The cytoplasmic activity was even more marked with nucleotide pyrophosphatase which was almost entirely absent from the cell walls. Nucleotide pyrophosphatase was active in all endosperm cells but particularly in some cells adjacent to the aleurone layer. In addition, all cells of the scutellum and embryo were positive for nucleotide pyrophosphatase activity, especially the developing fibres and xylem elements of leaves and coleoptiles, mature leaf xylem and phloem elements, scutellar provascular and vascular tissues and the epidermis of dark grown coleoptiles.