Water content, lipid deposition, and (+)-abscisic acid content in developing white spruce seeds

Whole seeds, and isolated megagametophytes, seed coats and embryos from whi te spruce [Picea glauca (Moench) Voss] were used to monitor water distribut ion by magnetic resonance microimaging, lipid composition by gas chromatogr aphy, and (+)-abscisic acid content ((+)-ABA) by enzyme-linked immunosorben t assay, during seed development. The highest (+)-ABA content was detected in the female gametophytic tissue, this at 11 d after pollination (DAP). Re serve deposition was evident up to 59 DAP in the female gametophyte and in the developing embryo. The maturation drying period occurred between 59 DAP and 93 DAP, At 59 DAP, the seed contained 24% water (g(water)/g(wet) (weig ht)), and within a 34 d period, the water content declined to 6% water (g(w ater)/g(wet) (weight)) (+)-ABA concentrations in developing seeds varied be tween 10 and 31 mu M. The decrease in water content accounted for the highe r (+)-ABA concentrations.