The localization of H
in developing Scots pine seeds. (A) Intense blue colour from TMB indicates the presence of H2O2 in the seed coat and flight wing at the early embryogeny. (B) The localization of H2O2 in the nucellar cap, cellular nucellus, and in the nucellar layers at the early embryogeny. (C) The localization of H2O2 in the megaspore membranes at the early embryogeny. (D) The minor amount of H2O2 in the seed coat and flight wing and the large amount of H2O2 indicated by the dark blue colour in the nucellar layers at the late embryogeny. (E) The seed treated with Tris-acetate buffer without TMB. cc = corrosion cavity, e = embryo, esr = embryo surrounding region, fw = flight wing, m = megagametophyte, mm = megaspore membranes, nc = nucellar cap, nl = nucellar layers, nt = cellular nucellus, sc = seed coat, sr = suspensor remnants.