Characterization of the natural chemical and osmotic environment of early wheat embryogenesis

Soluble carbohydrates, amino acids, and major inorganic ions were quantifie d and compared,vith the total osmolarity of the ovule, Most of the analyzed components increased rapidly in concentration, reaching a peak at 1 day po st anthesis (DPA) and decreasing quickly 1 day later. Within this time peri od, the osmolarity decreased from 1.49 to 1.18 MPa, The osmolarity then inc reased to 1.39 MPa at 4 DPA, and yet the overall concentration of analyzed molecules decreased, At 1 DPA, inorganic ions were observed at levels that could produce a high osmolarity (1.11 MPa), followed by the carbohydrates ( 0.37 MPa) and amino acids (0.07 MPa), Maltose was detected in ovules only f rom 0 to 2 DPA, Inositol was abundant in the ovules on the day of anthesis, but decreased to non-detectable levels after 4 DPA, This suggested that ov ules allow the rapid entry of solutes into the syncytial endosperm after fe rtilization, but are osmotically buffered through the increase and decrease of partly identified substances. Specific gravity tests on the liquid sque ezed from young endosperm supported this new hypothesis, Osmolarity in ovul es seems only indirectly related to morphogenetic regulation mechanisms, an d it may play a lesser role than the fluctuations of certain specific subst ances, The observed chemical changes offer insights into the rapidly varyin g nutritional needs of proembryos. Thus, this research yielded a useful com plex amino acid formula, derived from knowledge of the natural environment of the proembryo, and also an improved proembryo and ovule culture medium.